Proxy Posted September 3, 2014 Report Share Posted September 3, 2014 My DPMS LR308 (24in SS barrel) has point of impact change by 2-3 inches every 2-3 shots. I start out with 6 shots of cheap non-match ammo as a warm-up and to foul barrel after cleaning. When I start using the match ammo, I will get 2 shots at one point, right next to each other, centers 1/3 of an inch apart. Then the next two will hit 2-3 inches away from that, also right next to each other. And the next two will hit somewhere else near each other. Its not linear either. Sometimes the point of impact will move up right, sometimes it will move left, sometimes down left. It seems my rifle holds point of impact for 2 shots and then goes way off. But with cheap ammo it maintains 1.00 to 1.25 inch groups with almost no fliers. Does my rifle hate the match ammo, or am I doing something wrong? I usually take 40 seconds between shots to let the barrel cool off, and I do 6 shots (3 shots per target) before waiting for ceasefire to switch out targets. Has this happened to anyone else? The point of impact change is very significant. I use Black Hills 168g BTHP for my "match" ammo. I've seen it do consistant 1/3 groups out of a good bolt-action. My "cheap" ammo is SSA 168g BTHP. So ammo is almost identical, the Black Hills is higher quality. Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted September 3, 2014 Report Share Posted September 3, 2014 Randomness such as you describe, suggests a loose or non-spec barrel nut torque, IMHO. That may also not be the case, but it's a decent starting point. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted September 3, 2014 Report Share Posted September 3, 2014 Check your scope mount too Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 4, 2014 Report Share Posted September 4, 2014 (edited) All the above & try different brands of ammo , it could be just the loading in the ammo. Strange it groups like that . Usually when something is loose , its all over the place & you can't keep any kind of group ,but very large ones. Could be something inside the scope itself , but then it would do the same with all ammo used. This is a very strange issue. Edited September 4, 2014 by survivalshop Quote Link to comment Share on other sites More sharing options...
Proxy Posted September 6, 2014 Author Report Share Posted September 6, 2014 Thanks everyone! I will check those components. If it does turn out to be the ammo, that would be a shame, because that is the best match ammo I have seen in other rifles. Quote Link to comment Share on other sites More sharing options...
Gibbs Posted September 7, 2014 Report Share Posted September 7, 2014 (edited) Randomness such as you describe, suggests a loose or non-spec barrel nut torque, IMHO. That may also not be the case, but it's a decent starting point. FWIW, I concur that is a good start. I bought a used DPMS LR308 and was getting good, bad and indifferent targets. I bought another barrel from Brownell's and when I took off the gas block and gas tube I thought I'd see how this new PRI barrel Nut Wrench (for DPMS/KAC) would work. Well, imagine my surprise when not only doesn't it work on this particular nut, but the barrel nut was not even remotely tight. I unscrewed it with my fingers. No locktite on it either. It would probalby explain why my groups seemed to tighten up when I had shot a few groups. The barrel was probably getting hot, and getting just a bit tighter on that barrel nut. Odd thing is that this new DPMS/KAC Barrel Nut Wrench I got from MidwayUSA would not work at all. I was at the winery using their vise to hold the upper to install a new barrel and had to drive home and get my old "multi-tool" that had a AR15 style wrench on the one end. As Matt had said, I've also heard about this happening on a DPMS, and it can change the groups considerably. Edited September 7, 2014 by Gibbs Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 7, 2014 Report Share Posted September 7, 2014 Well, imagine my surprise when not only doesn't it work on this particular nut, but the barrel nut was not even remotely tight. I unscrewed it with my fingers. No locktite on it either. There should never be any Loc-Tite on a barrel nut. Please tell me you expertly assembled your own AR, and put Loc-Tite on the barrel nut... Quote Link to comment Share on other sites More sharing options...
Gibbs Posted September 7, 2014 Report Share Posted September 7, 2014 I called 2 gunsmiths this afternoon and asked them about the barrel nut and the size of the barrel nut as it seemed smaller than I had figured. The guy at Holland (Graaschaff Hardware) told me it was ok, just put blue locktite on it. Called the gun guy at On Target, Don Seguine, right after that and asked him that as well, about the odd size nut and being loose. He told me put blue locktite on it. I've never put locktite on a barrel nut before since I thought it was not needed if you torque it down to specs. Kind of news to me as well. As I now understand from you all that the barrel nut should never have locktite on it. Duly noted, and thanks! The gas block had some locktite on the barrel that was put on by DPMS, so not sure that is a great idea. Doesn't look like it would do much good there as it is a flat surface against a flat surface. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 7, 2014 Report Share Posted September 7, 2014 I called 2 gunsmiths this afternoon and asked them about the barrel nut and the size of the barrel nut as it seemed smaller than I had figured. The guy at Holland (Graaschaff Hardware) told me it was ok, just put blue locktite on it. Called the gun guy at On Target, Don Seguine, right after that and asked him that as well, about the odd size nut and being loose. He told me put blue locktite on it. They're idiots - never take your AR there for any "gunsmithing." I've never put locktite on a barrel nut before since I thought it was not needed if you torque it down to specs. Kind of news to me as well. As I now understand from you all that the barrel nut should never have locktite on it. Duly noted, and thanks! The gas block had some locktite on the barrel that was put on by DPMS, so not sure that is a great idea. Doesn't look like it would do much good there as it is a flat surface against a flat surface. Bull$hit - you Loc-Tited it. Gibbs, every move you make here, you keep digging yourself further into a hole, and you always have an excuse. You're a fraud, I firmly believe that. You're an "internet legend," and that's what you hope you'll be when you grow up - except you're grown up, by FAR. GO SHOOT SOME RANDOM TARGET AT 100 YARDS WITH YOUR RIFLE - ANY OF YOUR RIFLES - PROVE THAT IT'S 100 YARDS BY VIDEO, AND SHOW US YOUR 1/4 MOA GROUPS. You're a fake, man. It's that easy. Don't send me any more PMs, either - you won't like your responses from me. You have one coming from the PM you already sent. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted September 7, 2014 Report Share Posted September 7, 2014 Get in here, Gibbs - I see you lurking. Address my post above. ^^^ Quote Link to comment Share on other sites More sharing options...
Dane Armory Posted September 7, 2014 Report Share Posted September 7, 2014 (edited) I hate it when dumba$$ people put Loc Tite on parts that should be torqued on. Have to break out the heat gun just to fix their f#ck#ps. Idiots takin' advice from fools ! Edited September 7, 2014 by Dane Armory Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted September 7, 2014 Report Share Posted September 7, 2014 This thread is destined to be locked, nice it up or play elsewhere. This is my only warning. Play nice! Quote Link to comment Share on other sites More sharing options...
survivalshop Posted September 7, 2014 Report Share Posted September 7, 2014 Matt It made it to 11 posts , is that some kind of record ? <lmao> Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted September 7, 2014 Report Share Posted September 7, 2014 Matt It made it to 11 posts , is that some kind of record ? <lmao> I'm getting a little lax, blame it on old age... :D Quote Link to comment Share on other sites More sharing options...
shepp Posted September 8, 2014 Report Share Posted September 8, 2014 Thanks everyone! I will check those components. If it does turn out to be the ammo, that would be a shame, because that is the best match ammo I have seen in other rifles. Let us know what you found! Quote Link to comment Share on other sites More sharing options...
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