Thought I would take a minute to talk about an issue I had at the range last weekend, state what I think the problem was, and get some input from the members here to see if they agree or think I need to continue to look.
Last sunday I took my mega-arms AR-10 to the range to do a seating depth test for accuracy. I have already done a test for powder charge and landed on a good load that yielded 0.875 MOA accuracy. (7/8" groups at 100 yards). So I took that exact same load and varied seating depth up and down by 10 thousandths to see if accuracy improved. I also set one load up exactly as the first load for a control. Temps were the same that day, the chrono gave me the same speeds for the rounds, everything seems to be going fine, except the rounds were all over the place. Some as bad as 4 MOA. I could not for the life of me figure out why the same load from the same rifle would go to crap like that. As I started measuring I noticed that the vertical was well in line. less than 0.5" difference in impact vertically in almost all the loads tested. However the horizontal dispersion was terrible. So off to the house to tear in and see what I can find.
So after some digging and looking for any obvious culprits like loose scope or mounts, I notice the bipod had much more slop than normal in the traverse mechanism. The locking screw was good and tight, and it was tightly mounted to the rifle, so I thought maybe it was broken. So I took it off and tore into the mechanism to see what I could find. It turns out that the Traverse mechanism bolts onto the legs mounting platform of the Harris style bipod with a thread body, and then the tightening screw runs through the center of it. That mechanism was loose and was causing chaos in lateral dispersion.
Anyway, just thought that bit of information might help somebody in the future. So if you're having lateral dispersion issues that you just can't track down, and you use that style of bipod, check all the internal mounting bolts for tightness.
Last sunday I took my mega-arms AR-10 to the range to do a seating depth test for accuracy. I have already done a test for powder charge and landed on a good load that yielded 0.875 MOA accuracy. (7/8" groups at 100 yards). So I took that exact same load and varied seating depth up and down by 10 thousandths to see if accuracy improved. I also set one load up exactly as the first load for a control. Temps were the same that day, the chrono gave me the same speeds for the rounds, everything seems to be going fine, except the rounds were all over the place. Some as bad as 4 MOA. I could not for the life of me figure out why the same load from the same rifle would go to crap like that. As I started measuring I noticed that the vertical was well in line. less than 0.5" difference in impact vertically in almost all the loads tested. However the horizontal dispersion was terrible. So off to the house to tear in and see what I can find.
So after some digging and looking for any obvious culprits like loose scope or mounts, I notice the bipod had much more slop than normal in the traverse mechanism. The locking screw was good and tight, and it was tightly mounted to the rifle, so I thought maybe it was broken. So I took it off and tore into the mechanism to see what I could find. It turns out that the Traverse mechanism bolts onto the legs mounting platform of the Harris style bipod with a thread body, and then the tightening screw runs through the center of it. That mechanism was loose and was causing chaos in lateral dispersion.
Anyway, just thought that bit of information might help somebody in the future. So if you're having lateral dispersion issues that you just can't track down, and you use that style of bipod, check all the internal mounting bolts for tightness.
