My plan is to get to the range more frequently. I won’t have as high a round count, and I won’t have the longer distances, but I think there is a lot to be said for frequency. At least I hope there is. This range trip was five days after the previous one, which is pretty good for me.
I started the day with a dot drill at 120 yards. I remembered that I had been high on the last dot drill, so I adjusted down 0.1 mils. What I did not remember was that I was at 100 before, and at 120 this time:
Everything was uniformly low and right.
I was at least consistent. That would actually have made a nice group. If I had my zero correctly adjusted I’d have been doing pretty well!
The next order of business was the ladder test. I loaded up these test rounds before I ordered the Sierra 155 Palmas and the 3 lbs. of N140. The idea is that I have no idea what kind of powder I may happen upon in stock somewhere, so I’d better figure out what works with what, and how much of that certain what I might employ most advantageously.
A ladder test at 120 yards is not bound to yield the most spectacular results. The idea of a ladder test is to load 1 round of a certain charge, and so on and so forth, until the last charge is somewhere over book max (proceed at ye peril shipmate!!!). Each round is fired using the same point of aim on a large target board, ideally from at least 200-300 yards. The point up aim will tend to shift with each round, and by extension each charge weight. The shift is usually up the target as the charge weight increases.
The end result will usually look like a string going up the target. There will be clusters of rounds that happen to end up in decent groups. If these groups come from a sequence of charge weights, it usually indicates the presence of a “node”, which is a small range of charge weights where the rifle and load are more harmonious than the general range of charge weights. Settling on a load within this range not only means that it will tend to shoot better, but because it is within a small range it will tend to be somewhat forgiving of changes in temperature that can affect the way the powder burns.
After the initial test at 300, I would typically do another to home in on the node more precisely. Because the rounds from within the node grouped pretty well, it helps to move the shooting distance back to cause the rounds to have more dispersion on paper, which makes the results easier to identify.
This was a subsequent ladder with the TRG from 520 yards.
In ladder tests, the horizontal dispersion is usually ignored, as it is thought in this type of testing that the vertical dispersion is the result of changes in muzzle velocity. In other types of load testing, such as the Optimal Charge Weight (OCW), they take into account both horizontal and vertical.
One thing about ladder testing is that each shot must be identified and marked before the next shot is fired. If you can’t tell for sure what rounds were which, the test is pointless. Because of this, it helps to have someone else (that you can boss around, is young, and likes to run) do the numbering. If this is the nature of your helper, you must make it abundantly clear that each round has to have its own sequential number. It also helps to have a radio to communicate (micro-manage). Strict range safety procedures are, of course, essential.
I ran two ladder tests, both with Nosler 155 grain Custom Competition bullets, which are very similar to the Sierra 155 Palma (2155, which is the older style with the lower ballistic coefficient). I don’t plan on using these for my primary load, but things are so scarce as far as Bergers and the Sierra 155 Palma (2156, new style, better ballistic coefficient), that my reasoning was to use a bullet of the same weight to home in on the nodes. Perhaps my assumption that a charge that works well on one match 155 grain bullet will get me close to what works on another is flawed? I’d be interested to hear what you think.
Here are the results of the 155 grains with Varget:
I wrote in the locations of sequential shots on the right side so I could isolate them for size and look at them. It looks like the tightest group of 3 sequential shots was for shots 7, 8, and 9. I tend to doubt it with how I have been shooting lately, but this type of thing usually works out.
I was well over the book value from my Sierra manual. They also used Federal brass. What I’m not sure about is whether the case capacity of recent (past couple years) Federal brass is the same as what it used to be. I have heard that the brass is now less soft and has more capacity than is used to. All I know is that I did not expect to fire all the rounds. I expected my bolt to start to be hard to lift about 3 rounds before I fired them all. There were no signs of high pressure to be found whatsoever. That said, I don’t plan on pushing things any farther.
Part of bringing someone shooting is making it fun for them too. I brought along the “Black Death Challenge” target. It’s a fun type of “know your limits” target. Young Miss Rifleslinger was skeptical about her chances to be competitive against me (I’m not sure why). Her experience with this type of rifle is limited. I offered to shoot it at double her distance, which seemed to appease her.
I told her, get straight behind the rifle, lift the body up and back down to settle into the bipod, and engage the trigger with the finger at about 90°. I let her take a few rounds to get zeroed. I left all the strategery up to her.
A couple of the rounds were awfully close to touching the black in invalidating all her points, but she barely squeaked by with 15 points.
I moved back and shot the target. My strategy was to try several targets and try to keep from invalidating any points I had accrued:
One point was my total. That’s all I have to say about that.
Getting ready to leave I let her drive slow in the driveway as a reward.