I know are some old threads on crimping but after doing some tesing with new starline brass and two different brands of 69gr 223 bullets I think having that crimp ring that the 55gr have is best.
I have two Newer Colt 6920s ARs that I tested with.
I have new starline brass that I only did a light camfer to each case mouth.
I load up a few rounds (no power or primers) And cycled them.
The violent slamming shut of the BCG acts like a kinectic hammer.
The rounds did move after I carfully extract them
And they can move both ways
- Sometimes the round became longer from 2.252 to 2.259 (kinetic hammer effect)
- Sometimes the round became shorter from 2.252 to 2.230 (This is due to when the bullet hits the feed ramp)
They might be moving both ways a little. 1. When the bullet hits the feed ram it moves in some, then when it suddenly stops it moves the bullet out. So the net result can be +- in length
I did a light crimp and found while less they still moved.
BTW the 55Gr Hornday FMJ with the tamper crimp ring on the bullet never moved in my tests.
So not sure I want to trust these rounds in semi auto. They would be find for bolt 223 or if I gently one at a time feed into the my AR. But how can I trust my load development on these two ARs if the bullets are moving?
I know some people say "I never crimp not in 40 years" but have they actually tested the ammo if it moves or not? If they are just shooting for fun they might not ever know why their groups or fps go up and down. 2 MOA is good enough so its possible in 40 years they had a issue that never was noticed.
I have like 80 69gr loaded to test none of them have been crimped. I did this testing after originally seeing how much the feed ramps scratched up the bullets then found some moved.
I shot some using range brass a few months back and was not impressed with the accuracy of the 69gr. So ordered the new starline to see if it would improve groups.
I think they were 1.5-2.0 MOA using range brass. They were probably moving some too.
Im thinking 69gr with a crimp ring (Not sure if anyone makes these) might be best for AR 15 semis.
I have two Newer Colt 6920s ARs that I tested with.
I have new starline brass that I only did a light camfer to each case mouth.
I load up a few rounds (no power or primers) And cycled them.
The violent slamming shut of the BCG acts like a kinectic hammer.
The rounds did move after I carfully extract them
And they can move both ways
- Sometimes the round became longer from 2.252 to 2.259 (kinetic hammer effect)
- Sometimes the round became shorter from 2.252 to 2.230 (This is due to when the bullet hits the feed ramp)
They might be moving both ways a little. 1. When the bullet hits the feed ram it moves in some, then when it suddenly stops it moves the bullet out. So the net result can be +- in length
I did a light crimp and found while less they still moved.
BTW the 55Gr Hornday FMJ with the tamper crimp ring on the bullet never moved in my tests.
So not sure I want to trust these rounds in semi auto. They would be find for bolt 223 or if I gently one at a time feed into the my AR. But how can I trust my load development on these two ARs if the bullets are moving?
I know some people say "I never crimp not in 40 years" but have they actually tested the ammo if it moves or not? If they are just shooting for fun they might not ever know why their groups or fps go up and down. 2 MOA is good enough so its possible in 40 years they had a issue that never was noticed.
I have like 80 69gr loaded to test none of them have been crimped. I did this testing after originally seeing how much the feed ramps scratched up the bullets then found some moved.
I shot some using range brass a few months back and was not impressed with the accuracy of the 69gr. So ordered the new starline to see if it would improve groups.
I think they were 1.5-2.0 MOA using range brass. They were probably moving some too.
Im thinking 69gr with a crimp ring (Not sure if anyone makes these) might be best for AR 15 semis.
