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Posted: 7/4/2014 8:15:16 AM EDT
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8 yr old bushmaster xm15. 100 yard groups 10+". I get that it is probably won't be a sub moa gun but it isn't sub minute of pie plate. Nothing has been changed on the rifle since new. I am using an aimpoint comp m3, mounts are tight etc. accuracy is the same using factory 223, 5.56, and hand loads with really good quality control. Any ideas or items to check?
Thanks |
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It has never been terribly accurate, it is really bad now. Handloads were 55gr vmax over AA2230 not tuned for accuracy in this rifle just safe pressure but very consistent. I took the hand gaurds off, the barrel nut had the gas tube through it so I don't see how it could have loosened. Barrel crown seems ok but it is also the flash hider...not the most beatiful machine work i have ever seen. I have a barrel wrench and a torque wrench, should I check it that way?
Edited to add probably 1k rounds all together through rifle, certainly not more than 1500 |
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Quoted:
It has never been terribly accurate, it is really bad now. Handloads were 55gr vmax over AA2230 not tuned for accuracy in this rifle just safe pressure but very consistent. I took the hand gaurds off, the barrel nut had the gas tube through it so I don't see how it could have loosened. Barrel crown seems ok but it is also the flash hider...not the most beatiful machine work i have ever seen. I have a barrel wrench and a torque wrench, should I check it that way? Edited to add probably 1k rounds all together through rifle, certainly not more than 1500 1000rds in 8yrs? Am I understanding that correctly? Maybe you need to shoot more, have another person try it and shoot some groups at 25 and 50yds and see how it does. Or if you can put a scope on it and try for groups again. |
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I would just run down the basics.
Bore cleaned with a good/fast cleaning copper solvent like Sweets copper solvent, and keep cleaning until the dry patches are no longer coming out the bore blue. Next clean the chamber with a chamber brush and CLP, and even spin a dry mop deep into the chamber to make sure that you have the last step edge of the chamber cut clean as well). When you are done with this, then give the bore the barrel a good look. Granted at 1K, should have not shot the barrel out, but it could be rust pitted from incorrectly cleaning, or the lack of stored grease/oil in the bore for long term storage. Check for bullet strikes to the inside of the FS bore, and even pull the FS to give the crown a good cleaning (use a new crush washer when you put the FS back on). Check the barrel nut to make sure it's tight (+ 35 ft lbs, but not past 80ftlbs with the top spine void of the barrel nut indexed correctly to allow the gas tube to enter cleanly into the upper receiver channel for it). And lastly, make sure that your fire rate is no so great that you are over heating the barrel to cause it to whip uncontrollably/quickly plasma burnt the barrel out, and that you are not putting so much force on the hand guards when firing that you are torque bending the barrel from shot to shot as well. |
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