Lawrence97 Wrote:Went out today and tested with more neck tension and the Berger hunting 105 vld. I used CCI 450s with H4895 and AR Comp. All bullets were seated to mag length (2.260). With the extra neck tension I had pressure signs with 26.5 of H4895 so that is the only charge I tested. All groups are 5 shots from 100 yards.
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Lawrence,
The neck tension theory still holds true given the information in your latest photo.
If you look at the vertical bias of the first two groups; the H4895 and the 25gns of Comp there's no reason for this as you are obviously a shooter. The next giveaway is the first round low of the second group. This will have been fed into the chamber under control and therefore less chance of the bullet moving in the neck. The rest of the group will have been auto chambered with more violence. Bullets shift forward to kiss the lands and the start pressure spikes. I have experienced this myself and am also an F-Class shooter.
The MPI's getting lower on the target as the loads increase defies physics (see attached MPI calcs). I have no clue why you are shooting progressively lower as you load more powder in, all other things being equal.
Your group sizes of around the 1MOA mark for 4 careful shots is average for an average barrel.
Choosing a different bullet would seem the path of least resistance but I doubt it is the fault of the bullet. Vertical bias will follow you to the next bullet and haunt you - the data is not pointing at the bullet.