Which group would you pick and why?

[Gilly]

So this is more out of curiosity as they are all well under half moa and acceptable ES/SD and very respectable accuracy. When I looked at the results of a seating depth test I wondered is there a reason to pick one group type compared to another. Now this assumes I pulled the trigger perfectly each time and shooter had no influence on any one shot more than another. And yes it’s only 3 shots each so probably not statistically valid, I loaded more and shot 10 shot group later this was just for initial pass/fail.

Details
6 dasher with Lapua brass, varget and 110 ATips at 2800 shot prone from 515 yards. I had found a node I wanted to run and decided to try a seating depth test to see if it was very sensitive. Wind was under 3 mph at the time so very little wind to account for. ES was under 3 on each of the 3 sets (I know it’s only 3 rounds statistical bs blah blah)

Jump: 100k pretty much an equilateral triangle with 1.5” vertical and wind roughly .25 moa

Jump: 75k more of an L shape on its side with less than an inch vertical and just over an inch of horizontal. Under .25 moa

Jump: 50k nearly straight vertical line .8 inches tall no horizontal and in the .15 moa range.

Pictures attached for reference but which would you choose? Triangle, L or vertical?

 

[Campguy308]

I'd load more of number 3 to verify. If results are the same, roll with it.

 

[needham]

what happens when you split the middle between 75k and 50k jump?

what happens when you load to 40k, 30k, 20k jump?

how "good" is good enough for you?
you've gone this far whats another 20 rounds worth of testing?

 

[SN13]

Why is #3 so much lower down than 1 and 2.




I'm just posting this to make you further second guess yourself into the minutia.

 

[morganlamprecht]

my bet would be if you did this 10x youd have all the shapes alternate from one to the next randomly

but based on these pics and assuming results were 100%...id probably run 50 off and let it work to 100 and never worry about it

 

[jetjock07]

I’d try 40k and see if it’s similar to the 50k. I’d also run 60 and 70k to give yourself an idea of how much range of jump you had to play with before you needed to reverify lands

 

[Gilly]

So the reason I didn’t go less than 50 jump is because at .050 the bearing surface is getting a little ways out from the neck shoulder junction and wouldn’t feel comfortable running it that long with ammo going to a match in my pack, maybe that’s overthinking it.

The .050 is about .1 mil lower than the rest, I’m attributing this to it being the lowest velocity. 2795 On .050 vs 2810 on the .100.

Right after that seating test I loaded 10 rounds of the .075 load because it had the least vertical of all of them, even though we’re splitting hairs, and had the following with a singe 10 shot group at 515 yards.

Best 7/10 = .243 moa group
9/10 = .441 moa group
Total 10 shot group size including a possible flier was .556 moa.

I’m not sure I’m a good enough shooter to hold a quarter moa for 10 rounds while recording velocities every shot to boot. I’m gonna run with it that’s good enough for me. Rifle and load exceed my abilities I’m certain of that!

 

[supercorndogs]

I was thinking along the lines of another poster, I think. At what length does the POI shift happen between .05 and .075. If you start at that length
hypothetically, you wont have a poi shift as the throat erodes.

 

[Gilly]

I was thinking along the lines of another poster, I think. At what length does the POI shift happen between .05 and .075. If you start at that length
hypothetically, you wont have a poi shift as the throat erodes.

Yes very interesting thoughts now that I look at tape measure for more than group size reference the .075 and .100 jump are both about 3.5 inches low of you account for where POA is. .050 is noticeably lower that that even more than I originally thought. Looks like I have .025 of throat erosion at least before a POI shift. Thanks to those that pointed that out!

 

[Dthomas3523]

Yes very interesting thoughts now that I look at tape measure for more than group size reference the .075 and .100 jump are both about 3.5 inches low of you account for where POA is. .050 is noticeably lower that that even more than I originally thought. Looks like I have .025 of throat erosion at least before a POI shift. Thanks to those that pointed that out!

I’d still check it every few hundred rounds.

Theoretically it shouldn’t change POI, but that theory is also based on testing over a close to perfect/new throat.