Below are some groups from this weekend and wanted to get feedback on your conclusions.

Rifle & Load: 8x57 Mauser w/20" barrel; Remington brass, Accubond 200 gr bullets, 46 gr Varget, 2.980 COL. Started with a clean barrel. Did not clean while shooting.

I shot three groups with the same load - pictures below summary

Group 1:
I used this to make sure I was on paper. All of this brass had been cut below the minimum length for a 8x57

Group 2:
Brass length in spec

Group 3:
Brass length in spec, used a Lee factory crimp die. I read that they are supposed to improve accuracy. The left most shot was me jerking the rifle and I called it even before I looked through the scope. The other is a group of 4 shots.

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Group 1:



Group 2:



Group 3:

Question:
What caused the groups to tighten from #1 thru #3:

Choices:
The crimps improved the accuracy
The barrel shoots better fouled
The fouling and crimping improved accuracy
Not enough data

 

Not enough data.

First off, group one is 5 shots, what happened to round 5 on the other two?

Secondly, although I don't have a mic on your groups, group 2 & 3 look reasonably similar. (calling a flinch doesn't count...)

You need to shoot at least 3 identical groups (same number of shots, same conditions) with each load to say if there is a difference, at least from my vague memory of statistics.

Also, with the horizontal spread, I would say that technique is an issue here- all 3 groups have about the same vertical dispersion.

Looks like the rifle is actually pretty tolerant with this powder/bullet combination.

Yeah, a sample of one proves nothing, but it is reason to do more testing; #3 is obviously best as far as the test goes. Shoot more groups and post a matrix of the results.

Thanks!

I might get some more range time in before deer season. I keep this rifle to under 200 yards.

It's taken an elk bull, waterbuck, and red stag; but that was with a previous load that was about 2,300 fps; same components though.

This load is 2,430 fps.

I also used a Magnetospeed V3 I just bought. Throw your old chronys away, this is the way to go.

A-H,

Too small a data sampling ..... but from what's available.

I agree w/crbutler.

quote:

Also, with the horizontal spread, I would say that technique is an issue here- all 3 groups have about the same vertical dispersion.

Looks like the rifle is actually pretty tolerant with this powder/bullet combination.

Technically I consider you've probably arrived; and the loads are most likely spot-on. I've always had improved load perfomance when a Lee FCD, is used also.

All groups depict some amount of horizontal stringing.

Answer:

Either 1 of 2 or both.

1. Barrel channel pressure.

2. Bench technique - cheek weld, trigger pull & follow through.

Good Luck.

The trigger that was on here was not optimal, I changed this weekend. I had it hanging on my bench for a while and decided it was time to change it! That might help also.

You've gotten good advice so far. Definintely consider those things. My first reaction was that barrel fouling may be at work here. I have a .30-06 that needs about half-a-dozen rounds down the tube to shoot well. When I clean it, I know I need to put rounds down the tube before I go hunting with it.

LWD