The Complete Guide to Bolt Manipulation, Part 4: Delving into Finer Points

In Part 3 I demonstrated the major elements of my bolt technique. In this article I would like to try to fill in the empty spaces on the finer points.

I need to clarify some definitions of terms to keep this discussion from getting confusing. The bolt cycle, not the technique that is used to work it, but just the motion that the bolt needs to complete its function, consists of four phases. The simplest way to express them is “up, back, forward, down”, however those words don’t convey quite as much meaning when they are expressed individually without the full sequence. Likewise, the words “opening” and “closing” could easily be taken to mean more than one phase of the cycle. To avoid that type of confusion, here is the terminology I will use for the four parts of the cycle: unlocking, clearing, chambering, and locking.

On another terminology note, I use the words “bolt knob” to describe the roundish part at the end of the entire bolt handle, and the words “bolt handle” to describe the straight part that originates at the bolt body itself and terminates at the bolt knob.

The most important points to the technique are the instances in which a transition is made from one mode to another, such as firing to cycling the bolt, or from one direction of the bolt to another. Specifically, the critical points are the initial approach to the bolt just after completion of follow through and the point just after clearing as the bolt is at the extreme rear limit of its travel, and the hand transitions to propulsion of the chambering phase.

The best point of contact for my hand to unlock my bolt is between the two knuckles of my index finger, near the center knuckle. It’s important that the point of contact not be too far forward, because as the bolt knob is raised the hand doesn’t move forward with it. This means that the point of contact on the hand will shift forward on the finger as the bolt is unlocked. If it starts too far forward you might run out of room. If I start too far back, I find that my index finger doesn’t have the strength to unlock the bolt without being deflected down, which would be a wasted movement.

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Intended point of contact for the unlocking phase highlighted in blue.

3
You can see that upon completion of unlocking the point of contact has moved forward on the finger.

In order to have sufficient leverage to complete the chambering and locking phases firmly and speedily, the thumb must contact the bolt knob below, and near the second knuckle. The reason is similar to that in the unlocking phase. As the bolt travels forward in the loading phase, the point of contact on your thumb will shift slightly forward. If you run out of room you’ll send the bolt slamming forward as you completely lose contact with it, and your control of it.

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Intended point of contact for the chambering phase highlighted in blue.

Keep the hand relaxed. Don’t grasp the knob.

A minute amount of wrist rotation, pronation in the locking phase, assists in positive operation of the bolt. I estimate that I rotate approximately 15º-20º at the beginning of the locking phase.

Lubrication

I need to touch briefly on lubrication. I learned with my Sako 75 to keep a thin coat of grease on the shiny spots of the bolt. I was using only Brian Enos’ Slide Glide at that time. After I got my FN, a co-worker of the tinkering type was playing around with some common, off the shelf lubricants that are used in firearms, and came up with something I call Sam’s Secret Sauce. It’s actually a 50-50 mix of Ballistol and Lanolin (it’s an oily substance from sheep’s wool, also a component of Ed’s Red). Sam’s is a grease at normal room temperature, but will begin to liquify if you hold it for a few minutes. Now I put a thin coat of Sam’s over the Slide Glide. It’s slick! I can tell a difference. I keep it wiped off and freshly lubed as a matter of habit.

Remember to get the lugs and the camming surface for cocking of the striker.

Bolt Knob Size

This is as good a place as any to drift into a discussion of the size and shape of the bolt handle and knob. I have to admit that I’ve gone back on forth on the subject of oversized bolt knobs. In fact, I’ve done it over the brief time between two sequential articles. I think I am narrowing my idea of what is best. The question with knob size is one of reliability, speed, and efficiency. That makes this at least a three dimensional tightrope to walk.

The standard size knob has worked reasonably well. Some minor issues I’ve run into on a small minority of my bolt cycles have been missing the bolt knob on approach to unlocking and pinching my thumb on the ocular lens of the scope during chambering. At least one of these was exacerbated upon switching to the new stock, that being missing the knob, and perhaps the hitting the scope as well. Following are photos of what I think are the points of contact I use on the bolt knob and handle.

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There isn’t much margin for error.

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For the most part, this is plenty of bolt to hang onto during chambering and locking.  It could be just slightly larger.  The thumb can easily clear it after locking is complete and the hand begins to reacquire the firing grip.

The oversized bolt knobs come with their own issues. I have one on my TRG. Unlocking is never an issue. Witness the more than generous size of the contact surface on the knob:

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More than enough room.  Way more than enough.


Where the issue comes in is upon completion of locking. When it’s time to re-acquire the firing grip there turns out to be a bit of a speed hump:

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In order to return to a firing grip after locking, the thumb must either be extended open, or the hand must come out to clear the knob.

It’s not a huge deal, but it’s not ideal. I’m not knocking the maker of the knob (Charlie) at all. He does absolutely astounding work, and would have made anything I asked of him. This is what I picked out. The threads (the knob threads onto the handle) were cut so well as to make it feel like they were on ball bearings and the two surfaces mated up perfectly. When a teenage girl (not me, Young Miss Rifleslinger) is impressed by threads, that means that something common was done uncommonly well. He also helped me out of a horrible bind (TRG: The Untold Story [a horror movie]), was a complete gentleman in the truest sense of the word, and charged what I consider to be very little considering what he produces.

In the following photo, the two bolt knobs were compared while lined up to the best of my ability while taking my own photos while holding the parts at arms length after being awake for over 24 hours (at the moment I’m on about 26 [another tale of horror]).

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The next picture is the same one with the points of unlocking (blue) and locking (red) highlighted.

Points of Contact

You can see that the standard knob is barely adequate, while the oversize knob has a lot of extra real-estate.  

The following photo has some pre-school level drawing in an attempt to illustrate what I think would be a better bolt knob:

Re-Drawn knob
If you were wondering what my day job is, you can now safely eliminate any of those that require talent, skill, or brains.

The curved area that transitions from the bolt handle to the fat part of the bolt knob would be a very useful place to put the index finger for unlocking, but the standard knob has it too close to the bolt body. If you look carefully you may be able to see that I set it back a bit.

The two curved lines that are in the middle of the knob represent an extra band of knurling. I would leave the original one where it is in the photo. I would like just a little more aggressive texture than the factory knurling.

I didn’t make it any fatter than the original, although girth does increase efficiency. I just don’t know that I want too much of a departure from the original. The extra length is, I think, just enough to provide a bit more margin for error on the approach to unlocking, but not so much as to be an impediment in clearing the knob after locking.

Incidentally, take a look at this photo:

Bolt Comparison

The shiny bolt on the bottom is Pacific Tool & Gauge’s new one piece Winchester bolt. The handle is threaded to accept standard aftermarket knobs, or custom ones like the one Charlie made for my TRG. The top bolt body is mine. You can see by the seamless juxtaposition that I posses great talent, skill, and brains. I did my best to match up the angles and apparent sizes so they would be as equal as I could get them. Something in the angle prevented me from getting it perfect, but it’s very close.

Here’s a closer look at the handles and knobs:

Knob and Handle Comparison

The PCT knob is very close to being ideal, but I think it’s still a bit too long and I don’t like the smooth, straight ramp from the handle to the fat part of the knob. What I do like about the entire bolt is that it’s one piece, like the pre-64’s were, and that Pacific Tool and Gauge makes pretty much the best stuff (from what I hear). I also get tired of looking at off-center primer strikes and every round I have ever shot out of it has ended up with cratered primers. I’m guessing the firing pin hole on my bolt is slightly oversized?

Believe it or not, I have more to say about bolt work. To be continued…

 

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