I picked up a Red hawk rifles M40 in 308 a few months ago. Its been a pretty decent shooter so far with a few loads but I haven't done much shooting past 100 yards with it until today. It has 26" 1-12 twist barrel with wyatt detachable magazine and 6.5-24 Ziess conquest with mil dot.
I had worked up a load that shot really well at 100 yards. 168gr Berger VLD hunting with IMR 4895 for 2650fps with standard deviations in the low teens to single digits. Not a speed demon but was turning in some really impressive groups at 100 yards. I thought that I had it all dailed in until today. It started out well, here is two 5 shot groups at 100 yards.
Moved it back to 200 yards and shot two more 3 shot groups. It was matching up to my estimated corrections and was still shooting pretty decent.
Then I shot it at 300 yards. The groups really opened up. This was a 5 shot group and after seeing how spread out it was I shot three more to see if a pattern would start to appear. a second 5 shot group at 300 was even worse, with a verticle spread of 5 and 4-5" wide.
What in the world could cause it to fall apart like that? I don't think it was me because I shot some pretty impressive groups today with my 300 RUM turning in 1.25-1.5" groups at the same range.
I wonder if maybe the 1-12 twist isn't quite stabilizing the 168 VLD and its cause it to destablize somewhere past 200 yards. I'm really at a loss why it would just fall apart like that. I really expected it to shoot 2-2.5" after how well it was shooting at 1 and 2 hundred yards.
Any insight you all may have will be appreciated.