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10/21/2005 10:57:48 AM EDT
Does anyone recall an old post that spoke to over tightening the barrel nut and damaging the pin on the barrel extension.  Did damaging the barrel pin cause excess windage or excess elevation?
10/21/2005 11:21:52 AM EDT
[#1]
Usually what I've seen happen is the slot in the receiver deforms, that will allow there to be room for the barrel to move slightly from side to side, which would cause the windage to be off.
10/21/2005 1:34:49 PM EDT
[#2]
Also the Army Marksmanship Unit has published that the overtightening of the flash suppressor will cause a decline in accuracy.
They tighten just barely over fingertight.
10/21/2005 1:58:23 PM EDT
[#3]
I had an M16A1 upper that I overtightened the barrel on, and it lowered the point of impact alomst 3" at 25 yards.  I backed off the barrel nut one notch and it went back to the original POI.
10/22/2005 7:20:06 AM EDT
[#4]

Quoted:
Also the Army Marksmanship Unit has published that the overtightening of the flash suppressor will cause a decline in accuracy.
They tighten just barely over fingertight.



Are the Loctited on then, to keep them from coming loose?
10/22/2005 8:58:58 AM EDT
[#5]

Quoted:

Quoted:
Also the Army Marksmanship Unit has published that the overtightening of the flash suppressor will cause a decline in accuracy.
They tighten just barely over fingertight.



Are the Loctited on then, to keep them from coming loose?



No, since fouling at the muzzle crown can effect accuracy, the AMU way is to allow the FS's to be pulled at each cleaning to fully clean the fouling from the muzzle crown. Remember, AMU builds target rifles out of service rifles for their team.

You have to remember that when stated, the AMU ran FS's (true appearance of the service rifle), where as thanks to the Old assault weapons ban, you no longer half to run FS's in the CMP class to be service rifle legal.
10/22/2005 3:31:10 PM EDT
[#6]
I need to follow this one......in order to fix a crooked KAC RAS system issue I ended torquing the barrel nut to around 95 ft. pounds (maybe even a bit more). Bushmaster originally installed the barrel nut for me and I must say a buddy and I had to really lean on the barrel wrench to get the nut lose in order to re-align everything (had to of been originally torqued way over 80 ft. pounds). Not to steal the thread but since we're on the topic......should we back the nut off and re-tighten everything properly or just leave it? I've looked for any signs of stress on the upper receiver but everything looks OK from the outside.
10/22/2005 3:36:42 PM EDT
[#7]
If you tighten, then loosen a few times with the threads/surfaces lubed correctly, it allow the threads to mate and is enough to allow you to index to the next spine without going past the 80 ft lb limit.

With the barrel nut already torqued, any damage was already done, so just leave it alone.
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