S&B Match 30-06 Update

Picking up from last month in which Russ at LuckyGunner.com  generously sent me 2 boxes of Sellier & Bellot 30-06 Match Grade Ammunition  I present you with the results of my shooting.
The average muzzle velocity was 2863 fps, which seems perfectly reasonable for a 168 grain bullet from a 30-06.  What did not seem to be right was the signs of high pressure I got.  The bolt lift was quite stiff; it did not require special tools or anything, but on at least 2 of the shots I needed both hands.  I probably should have stopped sooner, but I had it in my mind to get at least a five shot group out.  All my groups have been sub-par lately, so including a photo would be a moot point.  If someone wants it I’ll post it.

Here’s the fired brass:

Primer Markings

This might be a slightly more revealing photo:

Single round resized

I’m not too concerned about the flatness of the primers.  This rifle does that with pretty much anything, Fed, Win, handloads, etc…  Also, the S&B primers are pretty flat to begin with:

Primers fired and unfired comparison

What is of interest are the rings on the primers, which to me indicate that they were really shoved hard against the bolt face.
This was the first time I have had indications of high pressure that were unmistakable.  A while back I once thought that I might have had a slightly stiff bolt lift once before during load testing with a 155 grainer doing about 3030 fps.  There was nothing unclear about these.
I shot these rounds just after I shot my first rounds after pillar bedding.  30 rounds of my own handloads had been fired prior to firing the S&B,  I put the rifle in the shade and shot my TRG for a few minutes.  When I returned to the aught six, the barrel was warm to the touch, but not at all hot.  The ammo, likewise had been kept in the shade with my other ammo.
I fired the S&B out of one magazine.  They fed without a hitch. 
After firing the S&B, I fired 3 of my own handloads- 3 rounds of 185 Scenars @ ~ 2740 at 4” clays from rice paddy prone.  Everything worked as it should have and I hit what I was shooting at.  No harm no foul.
I was hoping to find some physical evidence of a problem that I could say cause the high pressure symptoms.  As you may or may not remember, I pulled one bullet and found that there was 53.9 grains of this powder:

021

Not knowing what the powder is, I can’t say anything about how it may or may not have been the problem, but that would be the most obvious guess.
Something else I checked was the cartridge headspace.  I used a Hornady headspace gauge.  I can’t say for sure that it measures right at the datum line, but it is at least a consistent measurement of the case.  These are averages of 5 cases except for the first number. 

            All of the fired S&B cases with the primers in measured:                  2.034
            Average fired S&B case after decapping:                                         2.033
            Average unfired S&B case:                                                             2.029
            Average unfired Federal Fusion case:                                              2.032
            Average sized (neck bumped) handload:                                          2.033

The S&B rounds are sized a little bit more than I would size them, but I don’t think that four or five thousandths less than what seems like the chamber dimension would cause a problem like this.  Maybe it would lead to a premature case head separation after a few firings, but probably not a stiff bolt.  Anyone have any ideas?

Russ at Lucky Gunner was very apologetic, although he was not at any fault as far as I’m concerned.  Stuff happens.  He was supportive and encourage me to share my findings with you.  So that speaks well of him and his business as far as I’m concerned.

The Result of a Month of Turd Polishing

The point of all the work I put into pillar bedding my rifle was to improve the accuracy.  There were a few different ways it could have played out.  My stock could have been ruined, the rifle could have magically started to shoot all the bullets into the same hole, or somewhere in between.  My hope was a consistent 0.75 MOA shooting rifle from a bipod.  Hopefully the post title wasn’t a spoiler!!!
Here are some examples of groups before bedding:
Five shots from load development, bipod prone, from May or June 2011, Lapua 185 FMJ’s.  These were fired from a warm barrel in a “round robin” manner- one shot of one load on one target, then one shot of a different load on a different target, rotating through until there are five shots of the same load on each respective target.  As far as I can tell, it was about 1.3”:





A 10 shot bipod prone group (warm bore).  From the picture it looks about like 1.75”:




The bottom left group on the below target was four shots of Nosler 155 grain Custom Competition bullets, 0.96” center to center, warm bore.  The lower right group, 185 grain Lapua Scenars, was an inch (I had to round up from 0.996, because obviously it’s not that precise of a measurement):





I needed a cold bore example.  The following came from a three shot bipod prone group.  1.75”:

_______________________________
After


After bedding I cleaned the bore with Wipe Out foam.  I had been having very good results not cleaning the bore for several hundred rounds over several range sessions.  After all the gunk and debris that had been in and around the action I thought a thorough cleaning prudent.  The scope had also been removed and remounted.  I put the original Leupold Vari-X 3 3.5-10 and integral Warne rings back on after not being happy with the height of the Roedale 20 MOA rail.  Because of these two factors, plus the bedding being new, I was not sure if the system would need to settle in a bit.

All ready for my rifle to confuse me by creating only one hole from 10 shots, I posted a target, and loaded up my mags.  Here’s what came out:

022
Group size, center to center is 1.8”.  I was shooting at the center diamond, so there was a change in point of impact vs. before bedding.

I let the barrel cool to a consistently warm, but touchable temperature.  I took 20 to 30 seconds between each shot, as I have had better accuracy results with a break in between.  After a sight adjustment, I fired five shots:

025
                                              1.2” center to center.

Next five shots:

028
                                              1.3” center to center.

A four shot group:

058
That’s the best group the rifle has shot, although the improvement appears to be rather insignificant.

After that range session I looked at it and thought that I really didn’t have an apples to apples comparison to the collection of groups I had posted above.  I thought it prudent to get a 3 shot cold bore, a four and five shot warm bore, and a 10 shot warm bore.  To conserve ammo I decided to shoot one group.  I should have used 11 shots to isolate a 10 shot warm bore, but I just shot a 10 shot group.  To determine what shots were which so I could meaningfully measure it, I took a time lapse video of the target as I shot it:

10 shots

There was, as you can see, still a pronounced difference in the location of the cold bore shot from the rest of the group.  Here are the sizes:

            – 3 shots: 1.8”
            – 4 shot warm bore: 1.3”
            – 5 shot warm bore: 2.27”  (That one on the left really opened it up)
            – 9 shots warm bore would have been the same as five: 2.27″
            – 10 shot group: 2.3”

Not great shooting.  It was 91° out, and there was quite a shimmering of mirage that mayhave confounded things a bit:

Mirage notwithstanding, I’m quite disappointed in what may appear to be an extremely minor improvement in the rifle’s precision after bedding.  Could I have screwed the process up?  Maybe. 

What I learned from this process is that my secret dream of having a handy gun that could double as a “precision rifle” was, in this case, not realistically attainable.  I know that I’m not the first to have failed in this pursuit, although some have claimed success.

I had really big plans and dreams for the Sako 75, aka #1, that I’ve used faithfully for the last year.  I wanted a composite stock, a slightly heavier barrel, mil scope.  Keep it under 10 pounds, and it would have been a formidable rifle to do it all.  In the last month, I’ve discovered a broken bolt stop pin, failed on an acceptable scope mounting configuration, and now this.

It was made to be a hunting rifle.  For that application the level of precision is more than adequate.  I was hoping for more. 

I’m officially looking for a new rifle.        

Pillar Bedding the Sako 75, Part 7: Cleaning and Fitting

I removed the action from my stock after about 5-6 hours.  That makes it sound like I just grabbed it and gently pulled on it.  Okay, let’s break it down a little bit.

First, don’t forget to remove the screws that are holding the pillars to the action.  It’s not going to come out well if you skip that step (not speaking from experience). 
Next, when you remove the action, it’s best to pull it straight out.  That advice comes from a professional, not from me.  I was not able to pull mine straight out.  I seemed to have achieved some of the dreaded mechanical lock.  It was in solid and wasn’t wanting to come out.  No amount of pulling would get it.  Maybe a rubber mallet would have been just the thing.  I decided that a piece of 2×4 is softer than barrel steel.

001

002

You can see that it wasn’t a matter of a little tap.  Can you imagine how embarrassing it would be to be this brutally honest about your stupidest mistakes?  It wasn’t even enough for me to bash the barrel while holding the stock with my hand, although I could see that it did loosen it.  I had to attach a sling to the front swivel to get it out.  This project stopped being fun that day.

Anyway, here’s what was there:

003

You can see the broken portion where I believe I had the mechanical lock.  It broke free in that spot.  It’s a matter of cosmetics, but I did want it to look good.

004

The Devcon took advantage of the space between where the receiver was dammed and where the stock was dammed.  That’s a matter of inconvenience.  I could have shoved more Play-doh in to create a better barrier, but it would have affected how the action went in, which in hindsight I had to deal with anyway.  So I’ll put this question out to folks who know better, is it normal to have the Devcon fill into the center like that, or is there a good way to keep it out?

005

The smooth looking portions are the impressions of the bottom of the receiver.  The less defined parts are where the Devcon was up against the Play-doh and Silly Putty.  Although the flat portions look cool (to me anyway) for the most part, most of it has to be removed to get the action to go in.
The next step is to begin strategically removing the excess bedding.  For this is used Dremel attachments, files, and stones.  The Dremel was probably the most useful.  Hardened Devcon is very tough.  My Dremel attachment and several of my files seemed to be quite a bit more dull not too far into the job.  The exception was one of the Dremel attachment that’s a stone- nothing to dull there.
Prior to reassembling the receiver I cleaned the trigger assembly in white gas (Coleman fuel), based on a suggestion from Timney Triggers.  After it dried I put a drop of naptha (lighter fluid) in the hole in the housing that reveals the engagement surfaces for lubrication.
I had not been sure how much of the bedding would remain.  The sides needed to be almost completely removed down to the wood.  I had a project because I didn’t dam off the slot for the safety, so I had to very carefully remove all that bedding.  The first time I got the action to go in the safety worked, but not properly.  The button that allows the bolt to be cycled with the safety on did not have clearance to pop up when the safety was turned on, so I needed to relieve the opening a bit more.  Once the receiver fit, I had to check the magazine fit from the bottom, which revealed the necessity to remove a bit more material.  You get the picture.  Remove and fit.  Repeat as necessary.
I really wanted it to look professional.  It turned out looking like crap.  I could have done much better.  The sinking feeling that began with the sinking of the action into the uncured Devcon never quite went away.  Another part of it was that I didn’t quite know what it should look like when it was done, in terms of how much bedding needed to go and to stay.  I could have backed off with the Dremel at the appropriate time and pick up the files to keep my lines straight and pretty.
I also ended up with some voids due to not cramming the Devon in effectively enough.  Most of the voids went away with the removal that I would have done anyway.  Obviously the one that looks like a big black eye in the middle of the bedding is the one just aft of the recoil lug.  I did some extra research on this issue and learned that most people who seem to know what they are talking about say that flat bottomed receivers require a little more deliberate spreading of the bedding to avoid voids(that was a good sentence- Al Sharpton himself would be hard pressed to come up with that.  Proud be I much, er, I have much proud to be, uh, well that part wasworthy of Al Sharpton).

IMG_6924

The slightly discolored looking area is from a Sharpie when I was trying to figure out where the safety needed more clearance.

IMG_6926

 

IMG_6927

 

IMG_6928

 

IMG_6929

 

If I decide later that I care I will clean up the area in the barrel channel where I learned that blue tape won’t deter the Devcon from rolling on in and hardening.  It just looks like crap; I don’t think it affects anything.  And like Mrs. Rifleslinger said, “Who’s going to see it anyway?”  Well, just me, her, and you isn’t too bad.
 I am happy that the important parts of the bedding, around the recoil lug and pillars, seem to look alright.  I can even clearly see the imprints of the machining marks from the bottom of the receiver.
Now you, like me, are wondering if the whole thing is going to crack and fall apart upon the first shot being fired.  You’ll find out tomorrow.  Same Bat time, same Bat channel.

Pillar Bedding the Sako 75, Part 6: Devcon!!!

It would seem as though most of the work is done, with all the fitting, stock gouging, taping and Play-Doh playing we have done in the first 5 parts of this project.  Things are not always as they seem.  Let’s move on.

Before we mix and apply our bedding compound, Devcon 10110 Steel Epoxy, we need to make sure it won’t stick to the receiver.  The generic word for the item we need is release agent.  There are many things people use as a release agent.  Waxes that are free of detergent seem to be popular.  Brownells sells an aerosol spray that’s marketed to be a release agent, and it’s popular.  What seems to be just as popular is this:

50
                       Kiwi neutral shoe polish.  I had no complaints.

To apply the Kiwi, rub it on and buff it.  You should not have globs of it, or a noticeable film.  You just want the receiver to be slick.  I did not really see it on there.  I did two coats to make certain it was fully coated. 

We’re almost to the magic moment.  Let’s recap what we’re going to do.

Now that we have release agent on the receiver we are going to fasten the aluminum pillars to the action via screws.  I used an old action screw and a new one.  I had to trim the front one down so that it would hold the pillar snug to the receiver.

13
                  Too loose.  The tip of the screw is bottoming out.

15
So I trimmed it and dressed it with a file until it fastened the pillar snugly.

Somehow I lost of the picture of the pillars attached to the action prior to bedding.  Oh well.  Fastening them on ensures that they will contact the action perfectly in unison with the rest of the bedding, regardless exactly where the action is situated.  Make sure to get some release agent on the screws and the action under the pillars. 

I spent some time practicing placing the action in the stock as I would during the actual bedding.  This was very helpful.  I would guide the pillars into the holes, press down until it was getting close, then apply pressure between the two taped areas of the barrel.  Finally I would measure the depth of the receiver to make sure I had gotten it right.  It’s nice to have the feel of the thing before setting if for life.

One last thing.  I did not have a stable place to support my rifle as the Devcon cured.  I decided to make myself a rudimentary rifle vice out of 2 scrap 2×4’s, a wooden dowel, 2 clamps, and duct tape.

031

It worked!  Here’s the surgery table prepped:

032

Now it’s go time!  Applying the Devcon is different from all the preparation.  When I was prepping, I had a lot of time to fit, refit, measure, etc…  Once I even pulled off all the masking from the stock because I wanted to get it better.  With the Devcon you really need to just get it right the first time.  Not that it takes a rocket surgeon, especially if all your prep was good.

The Devcon has 2 components as most epoxies do.  There is a main ingredient and a hardener.  In this case they are mixed in a 2.5 to 1 (by volume) ratio.  If you go by weight it’s something like 9 to 1.

033
It seemed like I used a lot at the time.  I should have used more.  In the big picture, who cares if you waste a little your first time out.  Better to have it and not need it than the other way around, heh?

Mix it thoroughly without getting a lot of air into it.  Air bubbles will equal voids after hardening.  Then coat the stock and receiver thoroughly. 

038

037

036

035

034

When you place the action in the stock, what you want to see is the Devcon oozing out from the top and bottom.  That will tell you that you used enough.  I didn’t see that and was quite dismayed.  I don’t know if I should have done this, but I pulled it out and scraped for some more to stuff in.  I still didn’t see it ooze out, and had some difficulties getting it back to the right depth.  This just goes to show that you need to use more than you think you need.  I used more than I thought I would need, and still didn’t have enough.  So on second thought, use more than you think you need than you think you need.

Once you get it the action in, let it sit for about an hour or two.  Don’t use anything to clamp the action and stock together.  Doing so could introduce stress into the fit.  Just let them float there together.  All the tape prep you did, combined with the stickiness of the Devcon will hold them together fine.

Don’t clean it up too much right away.  Maybe get the big slop wiped and leave the rest.  Take a break for an hour or two.  Then return and clean up some of the ooze without disturbing the stock and barrel.  WD-40 on Q-Tips will remove the excess bedding compound nicely.

Now you just have to leave it for a while and stress out that you did it right.  Leaving it overnight would be best.  Sleep well!!!

Pillar Bedding the Sako 75, Part 5: Taping and Damming



One of the most important things to establish prior to the bedding process is how the action will sit in the stock.  This isn’t something that you can just leave to chance.  Now that you’ve got the stock inlet looking more like the Grand Canyon than a stock inlet, we can’t count on being able to just mash the action in and it turning out right.  For this (and for a lot of other things too) we’re going to use tape.

032

I apologize for the poor quality of the photo.I never took one specifically of the tape on the barrel that set the action height.  I’ll do my best to explain.  The barrel is wrapped with tape in 2 places.  The idea is that the tape will applied to a thickness such that if you were to press the barrel toward the stock between the 2 taped areas, the entire barreled action would be perfectly oriented up and down, and side to side.

What I noticed after I began taping the barrel is that the center of gravity of the barreled action was in the barrel approximately 12” forward of the receiver.  It would make sense that, if possible, the tape should be applied on either side of the balance point of the barreled action.  If done in this manner, the barreled action could just be set in the stock and there would be no rocking, leaning, falling, etc.  It would just sit there.
To apply the tape, I first just wrapped it several times. It reached the point where the sides of the tape were touching the barrel channel, but the action was still not at the right height.    When it got to that point I just cut 1″ lenghts of tape and applied them to the bottom.
When applying the tape, you need to be patient and take your time.  When it gets close, take frequent measurements until you get the action as high as the measurements you took prior to gutting your stock.  The front ring of tape, as you make it thicker, will raise the front of the action and lower the rear.  As you make the rear ring of tape thicker it will raise the entire action.
Also, while applying and test fitting this tape, make sure that the movement of the action in the stock is free of excessive friction that would confound your efforts to obtain consistent results.   The tape on the sides of the receiver may make it tight. In my case I needed to widen the inlet of the top of the receiver by a hair’s breadth.  Make sure that when doing this you have in your mind that it’s a surgical type operation, much different than the “hogging out” phase.

The next part of the job is keeping the bedding compound from going where we don’t want it to.  For this I used more tape (I only needed one roll of painter’s tape in case you were wondering.It’s expensive, so I thought it would be nice of me to tell you that).  Let’s cover taping the stock first: put tape where you don’t want the bedding compound to go on the outside of the stock.  That was easy.I really took my time to get the contours right.

025
Did you know that a circle is made up of many, many, tiny straight lines?

The taping of the receiver was more strategic.  Again, remember the goal of bedding.  The recoil lug should be the only thing that contacts the stock in the rearward force of the recoil.  In the downward force, the stock should provide as close to a mirror image as possible so that there are no points of stress between the action and stock.  To that end I made sure that the only vertical surface of the receiver that did not have any clearance built in via tape was the rear surface of the recoil lug.

011

The front and sides of the recoil lug got 2 layers of tape. The mag catch “housing” got a couple layers on the rear surface and the sides.  This being a flat-bottomed and flat-sided receiver, I also taped the sides to give a little clearance as well.  I overlapped the tape that extended from the sides to behind that tang so that behind the tang there were 2 layers of tape for extra clearance.  I also taped the barrel just in front of the receiver so that in the event the bedding compound should wander forward into the barrel channel, it would still be free-floated.

014
I should have about completely covered the exterior of the stock with tape to make for less mess/easier cleanup.

The next phase was damning.  Whoops, I meant damming.  Freudian slip.  What we’re looking to prevent is the bedding compound getting in places that will ruin things.  It could do that by coming into contact with things like: your chamber, lug recesses, etc… Something else that needs to be prevented is MECHANICAL LOCK.  That occurs when the bedding is allowed to ooze under a part that will enable it to trap your stock and receiver together.  That would be a very bad thing.  Dam it!(Yell that last part out loud)

Here’s what I used:

017

Silly Putty is great.It sticks to itself more than other surfaces.It’s easy to work with.It provides a nice barrier to keep the bedding compound away.  I got the Silly Putty to cover screws, screw holes, the chamber, etc…  I was going to get Play-Doh for the bulk of the damming, but I couldn’t find it at Wal-Mart so I got the generic stuff instead.  Let me say this and you can draw your own conclusions.It was moist and fell apart easily.  I didn’t taste it, but as a kid Play-Doh always was salty.  Moisture + salt + steel = ????  If I had to do it all over I would just go Silly Putty all the way, even though it would probably cost $5 extra.

018

019

If you need a thin piece of Silly Putty in a particular shape, you roll it out:

020

And cut it out:

021

022

I stuffed generic Play-Doh everywhere in the stock that I wanted to keep free of the bedding.

028

025
I already showed you this picture.  Now I want you to look at something else in it.  The safety cutout is on the right side of the stock just in from of the tang inlet.  It would have been easier for me down the road if I had plugged a little Play-Doh or Silly Putty in this area.

This marks the point of being almost ready to mix up some Devcon and go to work…

Pillar Bedding the Sako 75, Part 4: Disassembly

Now that the rifle’s stock has been “hogged out”, we are fully committed to seeing this project through.  The next step in the process is preparing the components in a way that will attempt to control where the bedding compound goes, does not go, sticks to, and does not stick to. 

First we need to get everything off the action that we don’t want or need to be there during the process.  Make your there’s no ammo in there (that was for all the lawyers and liability hand wringers out there).  Take out the bolt.  Remove the scope, rings, and base if you have one.

Next comes the trigger.  The hex bolt needed about 80 inch pounds of torque to get it free.  They must be strong out there in Finland.

010
                   This is the soul of a Sako.  They all have great triggers.

The removal of the trigger will reveal the ejector.  The ejector pin is overly long and holds in the bolt stop pin.  They both come out easily.

013
        The ejector pin is already part way out, but it does stick out when fully seated.
015
                                           The ejector removed.

The bolt stop pin came out easily… well, kind of.  I pulled, and a pin came out.  The stop was confusing me, because I had pulled out the pin, but it was still moving and operating as if the pin was still there.  I didn’t try to force anything, but just kept looking and moving it until finally it came out.  I then discovered this:

018

Yes, the bolt stop pin had been broken.  I have no idea how long it was like that.  I don’t know if it’s a good thing that it kept working and I kept using it (probably not), but that’s what happened.  I didn’t notice that anything was damaged with the stop or the receiver (in fact the stop itself showed almost no indication of use).  So- time for a detour…
_________________

…I have always been a believer in Col. Cooper advice that “Bolt work must be vigorous.  Show it no mercy!”  Maybe I took it too far.  I don’t think of myself as particularly merciless, but everyone who knows me seems to think so. 
I can’t say for sure whether the pin just failed, or if I broke it, though I suspect the latter.  This begs the question, should the bolt be shown somemercy?  Perhaps yes… or is it a question of a weakness in Sako’s design?  I did a little research and found this writeup which is a review by Barry Needham of Gunsite’s 270 class.  See paragraph 7 in which he references the troubles that the Sako shooters had. 

Again, I have reason to doubt my future with this rifle.  I will be giving some thought to what action will have the attributes I require.  It needs to inspire me (design, craftsmanship, etc…).  It needs to be reliable.  It needs to be strong.  It needs to be smooth.  I would like it to be very accurate.  Lately the rifle in my mind has been a Model 70.  I also like Mausers.  I don’t know where this will lead.  For now I will stay the course, but I will be more hesitant to invest any more into the platform.

Back to our scheduled programming…
_________________

Sako 75 011

The above picture is something I took prior to beginning any of this; I just included it for a reference to the following.  I had thought that the best thing to do with the mag catch assembly would be to remove it entirely (the piece circled in yellow).  It’s held on by a T25 Torx-head screw that threads into the receiver at about a 45° angle.  The hole actually ends in the lug recess area.  I don’t know for sure, but I suspect a strong thread locking compound was used (or a very strong Finn) to keep that bolt tight, because it was the first time I’ve ever had a Torx bolt slip.  I decided rather than to get myself in deep trouble by completely stripping it, I would go to plan “B”.  In retrospect I’m not sure if that was for the best.  It was very easy to drift out the pin that hold in the catch itself (the catch is outlined in red in the photo above).

More tommorow…




Pillar Bedding the Sako 75, Part 3: Crossing the Point of No Return

Abandon hope all ye who enter
With the pillars fitted to my satisfaction, the next step would take me past the point of no return.  This is because it’s necessary to remove some material from the stock.  There are 2 reasons for this.  The first is that the action screw holes need to be enlarged for the pillars to fit in them.  The second is that the stock surface that the action used to sit on needs to go away to make room for the bedding compound to form the new, perfectly mated surface.
Before you begin removing material from the stock, I would recommend taking some measurements of the depth of the action as it sits in the stock.  I did this by measuring how high the ejection port was over the stock, the height of the receiver where the bolt handle sits when closed, the rear tang, the top of the bolt stop to the top of the stock, etc…  My concern, again, was that I did not want to do anything that could interfere with proper feeding.  As I mentioned in the last article, the bottom metal doesn’t do anything to hold the magazine in place on my rifle.  The magazine is completely supported between the mag catch assembly, which is bolt to the receiver in the front, and the rear of the mag is supported by a spring loaded “friction sleeve” at the front of the trigger assembly.  Still, as I said before, I believe it’s better to get it to as close as possible to how it sat in the stock from the factory.
Measurements taken, I was ready to cross the line.  First I needed to enlarge the action screw holes.  I really wanted to make sure they would stay straight to allow the pillars to sit true.  What I used to open them up was a piloted “aircraft counterbore” from Brownell’s.  The pilot fit the existing hole like a glove, and the cutting portion was sold specifically for the pillar Brownells sells.

074
This pillar won’t fit in the action screw hole as it comes from the factory.
075
 The pilot fits the existing action screw hole.  The cutter will give a perfect fit for the pillar.

077
                                            Ready to rock!!!

076
                                               Now it fits.

 

Now it comes time to turn your nice looking, “good ‘nuff” stock into something that will temporarily look so bad as to make your wife ill for you.

Before:

Sako 75 019
                             Clean, untouched stock, meet Mr. Dremel…

 

50

019

You want to remove enough to allow the bedding compound to be thick enough and strong enough.  Somewhere, I don’t remember where, I read a figure that said you want it to be at least 1/8” thick in composite stocks, and ¼” thick in wood stocks.  The area pictured above is at the recoil lug, which is one of the most important areas for the bedding to be strong and purrfect.

Another important area is at the rear tang.  Again, before:

21

And after:

020

When removing all this material I had to check a few times to ensure that the action would be essentially “floating” on the bedding compound.  I wanted the action to go in noticeably deeper than it had been so that I could set the proper depth myself (I’ll explain later).  I didn’t want there to be any high spots of stock that would interfere with the “stress free” bedding job.  This took some detective work.  I would set the action in and it would stop.  I could rock it a bit to get an idea of where the high spot was.  I kept working the high spots and rechecking.  I could feel that there was some contact in the area of the recoil lug that was stopping the action.  Eventually I just pressed it in really hard and looked at the dented spot of wood inside.  Some strategic wood hogging, and the action just kind of feel into the cavernous hole I had opened up.
One part of the stock you don’t want to be touching much of is the part you will see.  This is the part of the inlet that “outlines” the action at the top.  Just make the inlet deeper.  The exception is that you may need to “surgically” remove just a few thousandths of width on the sides and rear.  This, again, is to keep the action from contacting any vertical surfaces other than at the recoil lug. 
One thing that stuck out in my mind while doing this is that you just have to take your time and get it right.  There is no room for a “Well I think it will probably work” attitude.  Just be patient and keep working until you know you have what you want.
I will explain this further in the next installment which will cover surface preparation.  Every step has to be informed of the thing that will come next.  If anyone is following this as it comes out with Dremel in hand as they read, I think I’m going to be sick for you.  You need to research this topic to death before undertaking it.

Pillar Bedding the Sako 75, Part 2: Fitting the Pillars

The first task I set about was to fit the pillars to proper length.  Initially I had planned on doing everything with files.  I was worried about my ability to keep the edge perpendicular to the pillar wall.  I didn’t want the pillar to support the action bottom irregularly.  During my research I found this part from Brownell’s:

004

It’s the components of a muzzle crown cutter and .30 caliber pilot, which fits perfectly in the inside hole of the pillar.  The tool assembled looks like this:

005

The pillars were a generic size.  I bought the long versions of the Brownells brand pillars for the Remington 700.  I had to trim them to the right length

I determined the proper length of the pillars by trial and error.  Basically they need to allow the same distance from action to bottom metal as existed in the stock as it came from the factory.  In theory the pillars could be trimmed after bedding, but I wanted to get it right ahead of time.  The final step was to assemble the pillars between the action and bottom metal, insert a magazine full of dummies, and function test.  Actually on the Sako 75, the position of the bottom metal does not influence the magazine at all.  Looks and feel are the only things that are affected.  I just wanted it to be right, and fit the pillars until it was.

The cutting tool I used to trim the pillars left the surface very bumpy:

008

After I got them close to the right length I hit them with some rough sandpaper to get the bit tool marks out:

010

Then smoothed it up with fine sandpaper:

007

Next I had to strategically remove material from the front pillar so that it would fit against the recoil lug while having the action screw perfectly centered within it. .  If I had it to do all over again with a Sako 75, I would buy thesepillars instead.  The difference being that the inside diameter is smaller, 0.280” instead of 0.300” like the ones I bought.  Here’s why:

I had to remove material from the wall of the pillar until the pillar would fit:

071

13

Here’s what the completed pillars looked like:

12

You can see why if I were to do this again I would choose the pillars with the 0.280″ inside diameter instead of the ones I used in which the inside diameter was 0.300″.  I had to cut it pretty thin to get the perfect fit I wanted.  The Holland’s pillars are 0.260″ which would be fine, but they are thicker on the outside too, which means more filing, which is no problem, and a different counterbore, which is a little expensive.  The Holland’s pillars are also over $30 a pair, compared to about $12 for both the others I mentioned.  It may be worth it to allow for a thicker pillar wall and thicker bedding between the pillar and the recoil lug.  What I did seems to have withstood the test of live fire though, for what it’s worth. 

This work was fairly easy and relaxing.  Cut, check, cut, check, sand, file, etc…  No problem, and no real skill involved.  There was really no pressure as nothing on the rifle had been altered to this point.  Next time there will be…

Pillar Bedding the Sako 75, Part 1: Overview

I have been wanting to pillar bed my rifle for a long time.  I have finally completed it.  I have outlined the process in great detail because I had difficulty finding information on the Sako 75.  I did some things well and other things I made mistakes on.  Hopfully the imformation that follows will be useful to people who want to pillar bed their own rifles. 

I am not a professional gunsmith.  I did the best I could with the information I could find and the tools I could afford.  It did not turn out perfectly, but it was not a total disaster either.  I will try to be as brutally honest as possible.  If I made an obvious error I will put it in red so it’s really obvious.  I also would appreciate feedback that I could not easily find prior to doing this, so that anyone reading can look to the comments of people more skilled than I for further guidance. 

Don’t take what I say as the way to do it, although it is a way.  If you have any doubts there are a lot of professionals who can do the work for you.  Proceed at your own risk. 

_______________________Ever since I’ve had my rifle, it has had some issues with vertical stringing.  Adding a cheekpad seemed to help a little, but I have wanted to see if there was something that bedding the stock would accomplish.  I have had the materials for quite some time now.  The primary thing stopping me from executing the project was this:

001 resized

I did not have a suitable place to work.  Upon completion of the new workspace, priority #1 was bedding the rifle.  The other obstacle was the knowledge that if I messed it up I could ruin my stock, which of course would necessitate buying an even better stock at a premium price…
Pillar bedding is the process of placing aluminum pillars, which are short cylindrical shafts that surround the action screws, in between the receiver and bottom metal (trigger guard and floorplate).  The pillars provide a rigid, non-compressive structure so that torqueing the action screws doesn’t compress the stock.  That’s the pillar part.
The bedding part of pillar bedding is the process of using, in my case, a steel impregnated epoxy compound to form a mirror image of the bottom of the action in the stock.  The theory behind it is that the rifle, when fired, acts like a tuning fork.  The vibration of the rifle affects how the bullet leaves the barrel.  Irregularities in the stock that contact the barrel result in irregularities in the harmonics of the barreled action.  Furthermore, it can impart stress into the action when it is torqued down.

001
Aluminum bedding pillars and Devcon 10110 Plastic Steel Putty are the materials.

On most rifle actions there is a thick piece of steel near the front that contacts the stock.  This is called the recoil lug.  The goal, as I understand it, is that the rear face of the recoil lug should basically be the only thing that contacts the stock in the horizontal motion, and that in the vertical motion of the action it should be uniformly supported by the bedding and the pillars.  Theoretically this uniform support will make the rifle behave much more consistently, and therefore much more precisely (smaller groups).
The main resource that I used as a guide for this process is a thread in the Sniper’s Hide forum called Bedding Project.  It used to be a lot more useful until the pictures on the original post were reallocated by the photo server to pictures that have absolutely nothing to do with pillar bedding.  I still recommend that if you are serious about bedding your rifle to read the entire thread several times.
Different action types present different challenges in pillar bedding.  The primary thing that caused me some head scratching initially was the location of the Sako’s recoil lug in relation to the front hole for the action screw. 
This is supposed to surround the action screw:

003

And sit below the action at its action screw holes.  The front hole on the Sako 75 is just behind the recoil lug:

Sako 75 006
Hopefully that adequately describes the challenge I was facing.  In the next segment I’ll begin the actual work…

SWFA SS 3-9×42 Preliminary Scope Tracking Test

Why preliminary?  I was using the iPhone voice memo function to record my sight correction numbers.  I later discovered that loud noises, like, say, a braked .338 Lapua Magnum, causes the microphone to stop working until the next big noise.  I lost about half of my data.  Note to self: WRITE IT DOWN!!!

The target:

Tracking Test Target

Think of it as a more sophisticated version of the old “box test”.  You “read the reticle” to measure the difference between the point of aim dot and the dot you want the bullet to hit.  Dial the difference that you measured, because the knobs are in the same increments as the reticle (hopefully not just close).  Aim at the original dot and fire.  The bullet should hit the second dot if reticle, knobs, and you are all in perfect accordance.
First I had to zero it.  Based on what I saw when doing my rough bore sighting, I was expecting to have to hold under about 3 mils.  I tried that and missed the paper.  I decided to try to just aim at the “zero” dot with the crosshairs and hit low about 2.1 mils.  I then held over 2.1 mils and got a hit on my dot.  Easy.

Zeroed

The next step was to leave because I was out of time.  I came back about 2 weeks later in 91° heat in the shade.  I decided after a few shots I couldn’t shoot in the shade, because the object that was giving me shade (my truck) was giving the muzzle blast something to bounce off of and the concussion was almost painful.
The first thing I did was to dial up 2.1 mils.  That put me really close, just low and left, about 7:30, about an inch away from the target (about 0.3 mils).  I dialed 0.3 mils, up 0.1, then hit farther left and a bit high, then realized that I’d dialed the windage knob the wrong way.  It took me 4 shots to get it dialed to hit the dot.  Lesson: single shots can leave you chasing your zero, even with a “laser beam” of a rifle.
Here’s the target when I was done for the day, 34 shots and a bruised shoulder later.

Preliminary Tracking Test SS 3-9x42

Here’s what I can tell you despite my loss of data:
The adjustments seem to be more than what I read in the reticle, somewhere on the order of 5-10%.  I get that because 2 of the dots were exactly 5 mils apart (very clearly).  I dialed 5 and got an impact 0.4 high.  There was another example that was more dramatic because the dots were farther apart, but I lost the exact data on what I dialed.
The other thing I found with the scope is that the return to zero was very consistent. 
I’ll do the test again and let you know how it goes.