LensWork Posted June 21 Report Share Posted June 21 I am getting some very odd groups with my new custom Aero Precision M5, in .308 Winchester. With several match grade factory loads at 100 yds., I am getting three rounds of a five round group that are a cloverleaf measuring ~ .25” center-to-center, with the other two rounds high and expanding the overall group to ~ 1”x1”. I have gotten these virtually identical groups with Federal 175 7.62x51 MK HPBT, Nosler 175 Custom Competition, Barnes 168 TTSX and Lapua 175 Scenar-L. The groups are fired semi-auto, magazine fed. The groups have all been fired at about the same pace: one round every 30-60 seconds, so no significant heat-cycling of the barrel. I am getting the same results from multiple different magazines — all Mag-Pul — 10 round, 10 round with -5 round limiter and 25 round M118LR magazines, so I can’t attribute it to a specific magazine. The barrel is a Criterion 18” Hybrid; comp is a Precision Armament M4-72; BCG is JP Low Mass with a JP Enhanced bolt; optic is a Trijicon Credo HX 2.5-15x56mm. I have duplicated the same results on different trips to the range. I am at a loss as to explain how I could be getting 3/5 rounds in essentially one ragged hole and the other two high “flyers”, with multiple different factory loads. Any ideas? Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted June 21 Report Share Posted June 21 I had a gas block that was just barely touching the rail when fired, that gave me some erratic groups until I found it. Quote Link to comment Share on other sites More sharing options...
shooterrex Posted June 21 Report Share Posted June 21 Scope mount loose? Barrel nut not tight? Gas block touching rail? Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted June 21 Report Share Posted June 21 Is it the difference between left and right side of the magazine? Try one round in a mag for each of five shots so they all come from the same side. Quote Link to comment Share on other sites More sharing options...
LensWork Posted June 22 Author Report Share Posted June 22 3 hours ago, Armed Eye Doc said: Is it the difference between left and right side of the magazine? Try one round in a mag for each of five shots so they all come from the same side. That is what I thought it could be; I am getting the same results using multiple different magazines, so if it is related to the round being chambered from one side of the magazine, and it’s not the magazine itself, I wonder if it could be the barrel feedramp??? Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted June 22 Report Share Posted June 22 15 minutes ago, LensWork said: I wonder if it could be the barrel feedramp??? Like in tearing up the bullet, that would be easy to figure out anyway. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 22 Report Share Posted June 22 1 hour ago, LensWork said: ...so if it is related to the round being chambered from one side of the magazine That will immediately indicate an issue with the ejector face... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 22 Report Share Posted June 22 P-Mags. First round is left, top round is right - always - like it should be in a mag. 20 rd mag, last round is right. 30 rd mag, last round is right. Been that way for decades, before Big Army fucked that up. Ignore Big Army. You loaded 5 rounds, in a P-Mag. First was left, etc. 5th was left. No other way around that. It is what is is. You had 3 rds clovered. You had 2 rds out, but close (but you haven't posted any pics or your groups yet... just of your pretty gun...)... <<< BIG deal right there. Get your group pics up. Post 'em. You have a problem with the profile on your ejector face. Nothing more. Post pics of the face of your ejector, so we can look at it. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 22 Report Share Posted June 22 @LensWork, let's get back to the beginning, on your build... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.