Sctech Posted March 2, 2016 Report Share Posted March 2, 2016 Hello everyone, I am new to the forum. I was hoping for some guidance on an issue I am having. I have a DPMS AR10 with an 18" bull barrel, no flutes or break. My first shot and even the ones after if I wait 15mins between are great. The problem comes if I shoot with minimal time between shots. Not rapid fire roughly 1 shot per minute. At this rate the 3rd shot starts to go high and by the 6th shot I am 5 inches high at 100yds. If I wait a while and take another shot, it is back to center. What would cause this? Quote Link to comment Share on other sites More sharing options...
shepp Posted March 2, 2016 Report Share Posted March 2, 2016 (edited) Hello everyone, I am new to the forum. I was hoping for some guidance on an issue I am having. I have a DPMS AR10 with an 18" bull barrel, no flutes or break. My first shot and even the ones after if I wait 15mins between are great. The problem comes if I shoot with minimal time between shots. Not rapid fire roughly 1 shot per minute. At this rate the 3rd shot starts to go high and by the 6th shot I am 5 inches high at 100yds. If I wait a while and take another shot, it is back to center. What would cause this?what grain and brand of ammo? btw welcome to the forum from Wisconsin, feel free to post in the intro area Edited March 2, 2016 by shepp Quote Link to comment Share on other sites More sharing options...
washguy Posted March 2, 2016 Report Share Posted March 2, 2016 Welcome to the forum Sctech...is it a factory built rifle ? Wash Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 2, 2016 Author Report Share Posted March 2, 2016 It is not. It is all dpms parts I assembled Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 2, 2016 Author Report Share Posted March 2, 2016 I have tried 150-180 grain all with the same results. I believe 167 match grade remington ammo was the least effected. I haven't tried hand loads yet. Quote Link to comment Share on other sites More sharing options...
EasyEJL Posted March 2, 2016 Report Share Posted March 2, 2016 Did you use a torque wrench on the barrel nut? and did you do the tighten then loosen and repeat a couple times before the final? Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 2, 2016 Author Report Share Posted March 2, 2016 I did use a torque wrench but it was a couple years ago. The only one I ever did and can't remember if I did it multiple times. Quote Link to comment Share on other sites More sharing options...
washguy Posted March 2, 2016 Report Share Posted March 2, 2016 I did use a torque wrench but it was a couple years ago. The only one I ever did and can't remember if I did it multiple times.SC I just remembered last year I helped my buddy build a 308...his rifle did the same thing almost...but it just wouldnt group after a cold barrel shot..I told him to send it back...which he did...put on the replacement barrel and it shoots sub moa.......$hit happens...send it back and get a new oneWash Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 2, 2016 Author Report Share Posted March 2, 2016 Thanks Wash, really the only thing I could come up with as well. I did bring it to dpms to check it but they only took 3 shots and said there was no problem. Any recommendations on match grade barrels? Quote Link to comment Share on other sites More sharing options...
EasyEJL Posted March 2, 2016 Report Share Posted March 2, 2016 I did use a torque wrench but it was a couple years ago. The only one I ever did and can't remember if I did it multiple times.it would not hurt to loosen + retighten it Quote Link to comment Share on other sites More sharing options...
washguy Posted March 2, 2016 Report Share Posted March 2, 2016 (edited) Thanks Wash, really the only thing I could come up with as well. I did bring it to dpms to check it but they only took 3 shots and said there was no problem. Any recommendations on match grade barrels?SC here ya go...Survival likes this mfg http://criterionbarrels.com/barrels/.308_AR/ar-10-hybrid I like this one too...the new hybrid looks sweet!I have some of these https://www.rainierarms.com/barrels/308-7-62 not in match but they all shoot sub moa for me...and these folks are nice to work with Wash Edited March 2, 2016 by washguy Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 2, 2016 Author Report Share Posted March 2, 2016 Thanks guys, I will try resetting the barrel first before I go with a new one. I appreciate the input. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted March 3, 2016 Report Share Posted March 3, 2016 I worked on a brand new CMMG that did the same thing & it was the Barrel that was loose , from the Factory . Quote Link to comment Share on other sites More sharing options...
EasyEJL Posted March 3, 2016 Report Share Posted March 3, 2016 yeah, being at the loose end of tightness tolerance, plus the combination of aluminum vs steel heat expansion could easily do that Quote Link to comment Share on other sites More sharing options...
washguy Posted March 3, 2016 Report Share Posted March 3, 2016 (edited) Sctech Wow forgot to ask...new barrel not broken in? old barrel broken in?....have you cleaned the barrel properly for copper fouling lead fouling?and of course you know that theres a fine line between having the barrels condition too clean ....just trying to solve the puzzle...but in the end it Can be a bad barrel ....oh...what about the optics...watcha got? Wash Edited March 3, 2016 by washguy Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 3, 2016 Author Report Share Posted March 3, 2016 I have a Springfield 6x26x56 30mm tube and a one piece mount.The barrel was bought from a private party and supposedly never fired or mounted. I did follow proper break in procedures as listed by a few barrel manufacturers. To date I would say less than 200 rounds through it for sure, probably closer to 100.Similar question I always wondered because I have other ones I know we're not broke in properly but shoot great, is there any benefit of trying to break in an old barrel? My understanding is basically the break in process is sealing any micro imperfections to keep from copper fouling. Quote Link to comment Share on other sites More sharing options...
washguy Posted March 3, 2016 Report Share Posted March 3, 2016 SC if it were me.....I would re -torque the barrel nut...and while the barrel is off I would give it a good inspection...look at the crown of the barrel toothen clean the barrel with the copper fouling/lead fouling chemicals....then go shoot it after you torque it back down...you may be surprised.but wait a min...you got 100 /200 rounds down the pipe and its just now doing it? what about before...did it ever group real nice? Wash Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 3, 2016 Author Report Share Posted March 3, 2016 Most of the shots were from break in. 1 shot, clean, 1 shot, clean, and so on. It dosent rise until it gets warm, so I didn't notice it right away. Quote Link to comment Share on other sites More sharing options...
washguy Posted March 3, 2016 Report Share Posted March 3, 2016 (edited) Most of the shots were from break in. 1 shot, clean, 1 shot, clean, and so on. It dosent rise until it gets warm, so I didn't notice it right away.SC what the hell clean it up and start over....I came across a bench rest shooters site while searching for some answers for you and one statement was a muzzle heavy rifles shot string will rise. but yours is not consistent ...so I dunno....this is the nitty gritty lol http://www.6mmbr.com/verticaltips.htmlim no benchrest shooter...they wouldnt even let me in the parking lot of a match...I got kicked off a trap field during a tournament for laffin...so I dunno bout this benchrest vood doo stuff Wash Edited March 3, 2016 by washguy Quote Link to comment Share on other sites More sharing options...
Sctech Posted March 4, 2016 Author Report Share Posted March 4, 2016 Thanks again, I will give it a once over and try it again as soon as it warms up a little here Quote Link to comment Share on other sites More sharing options...
washguy Posted March 4, 2016 Report Share Posted March 4, 2016 (edited) SCgood luck...it may work out for you. Wash Edited March 4, 2016 by washguy Quote Link to comment Share on other sites More sharing options...
sapper299 Posted February 19, 2018 Report Share Posted February 19, 2018 Sounds like your barrel is allowed to shift slightly as it heats. What happens if you shoot more than say 10 rounds- does it settle in or does it still move around? I have an F class rifle that will shift as it gets warm, but then it settles in. Not ideal but it was at least predicatble. The whole thing was taken apart, re torqued, bedded, then floated when beedding did'nt work, pressure pad up front added...nothing worked, it was just the stress in the barrel. That became a very expensive stake for my pepper plants finally. Quote Link to comment Share on other sites More sharing options...
shepp Posted March 18, 2018 Report Share Posted March 18, 2018 On 2/19/2018 at 7:46 AM, sapper299 said: Sounds like your barrel is allowed to shift slightly as it heats. What happens if you shoot more than say 10 rounds- does it settle in or does it still move around? I have an F class rifle that will shift as it gets warm, but then it settles in. Not ideal but it was at least predicatble. The whole thing was taken apart, re torqued, bedded, then floated when beedding did'nt work, pressure pad up front added...nothing worked, it was just the stress in the barrel. That became a very expensive stake for my pepper plants finally. Posts from nearly 2 years ago hope he got it straightened out by now Quote Link to comment Share on other sites More sharing options...
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