AR Sponsor
Posted: 9/9/2008 4:57:06 PM EDT
|
My father recently bought a CMMG 20 inch upper with A2 flash hider and 1-9 twist. The first day we had it at the range, we sighted it in at 25 meters, then he shot 30 rounds at 100 yards. We went down to check the target, and there were 5 key-holes. These were 55 grain soft-tip bullets. We went home and measured the rifling and it WAS 1-9 twist. What could cause this?? Thanks |
Most likely barrel defect. Any signs of copper on end of barrel or flash hider. Could try different ammo. Possible you have defective ammo but ..... Since recently bought from CMMG please return it for another one. Not much a citizen can do for this problem other than changing out the barrel. Can you check what is written on the barrel? Can you put a barrel into the end of the rifle to make certain it does not fall in. This is to check that you did not get a larger caliber barrel mixed up with you 5.56. |
|
Quick question for you? When you sighted in at 25 meters, was your target up at 100 yards at the same time? I have seen previously, where I had a target at 100 yards, and someone was shooting next to me at 50 yards, where their bullets have destabilized after going through the cardboard, and key holed on my target. For me, it was easy to notice, since I was shooting a .30-06, and they were shooting an AR.  Otherwise, check your bore, check the muzzle crown, and check the flash hider for damage if one is installed. How was the accuracy? How many holes in the target? What brand of ammo? |
On this note, I had a VMAX bullet tip that was pretty deformed, and I wanted to see if it would affect accuracy, so tested it with 11 other rounds. These were all handloads that I had worked up myself, and I was curious what effect it would have. I tested at 50 yards, from a bench. I loaded 5 rounds in one mag, 6 in the other. The deformed round was the last round in the first mag. First 4 shots went in a nice tight group, 5th shot went about 2" low. All 6 from the next mag were with the first group. It seems that the tip damage did in fact have an impact on the accuracy.
|
AR Sponsor