I finnally got around to threading my barrel, so yesterday I got to test out my 20" Bushy that I had previously built(all Bushmaster parts) during the ban. it had the Y-comp pinned in place, and apparently pressed on. I got my upper back yesterday and the end of the barrel was pretty scratched up, along with two small scratches on the bottom of the front sight, it seems that the gunsmith clamped the end of the barrel and when he pulled the brake off the barrel twisted. I figured oh well I can refinish it, thats not my problem.

I fired 200 rounds and it was shooting about 16" to the right but it seemed to get better, to about only around 8". Before it was threaded the rear site was dead center, now it is almost all the way to the left, the accuracy was not affected at all, it actually seemed better(around 1.5"), but as it is open sites it tends to vary.

My question is will a few scratches on my front sight, no dents, affect my windage this much? my front sight is not loose, nor does it look crooked. can threads affect the point of impact(not accuracy)? What can be done to fix this, should I take it back?

All replies are appreciated

It almost sounds like your gunsmith may of bent or twisted the front sight assembly a bit? It might just need to be removed and installed again... It also could be that the barrel nut is over torqued, slightly bending the alignment pin?  Id contact the gunsmith and explain the problem to him and see what he has to say about it...

Sounds like something got twisted/bent.  I don't think I would take it back to the same place .

Quoted: It almost sounds like your gunsmith may of bent or twisted the front sight assembly a bit? It might just need to be removed and installed again... It also could be that the barrel nut is over torqued, slightly bending the alignment pin?  Id contact the gunsmith and explain the problem to him and see what he has to say about it...

I had a suspicion that was the problem, I can do the work myself, what parts would I need, can I use the same parts again?

Id start out with knocking the taper pins out of the FS to see if they are cracked or had been forced out the wrong way... I don't believe bent pins is an option, the pins usually snap in two before they bend... If your GS used a press to try and force the FS taper pins out the wrong way, he pretty well could have screwed up the alignment holes in the barrel and FS...

To replace the barrel extensions alignment pin, you will need to remove the barrel nut and the barrel from the receiver... Grab the pin with rib joint pliers then twist and pull, out she comes... To install the new pin, lubricate it and lightly tap it in with a brass hammer... Be sure to lubricate the barrel nut threads and the outer rim of the barrel extension to prevent it from twisting while torquing... Do not exceed 80lbs of torque when tightening the barrel nut...

Thanks for the replies,
My GS didn't remove the barrel or front sight he just clamped the upper reciever and barrel, but I thought his price, $10, was great, but I guess I got what I paid for. Guess I should have just paid the extra and had ADCO thread it

Quoted: Id start out with knocking the taper pins out of the FS to see if they are cracked or had been forced out the wrong way... I don't believe bent pins is an option, the pins usually snap in two before they bend... If your GS used a press to try and force the FS taper pins out the wrong way, he pretty well could have screwed up the alignment holes in the barrel and FS... To replace the barrel extensions alignment pin, you will need to remove the barrel nut and the barrel from the receiver... Grab the pin with rib joint pliers then twist and pull, out she comes... To install the new pin, lubricate it and lightly tap it in with a brass hammer... Be sure to lubricate the barrel nut threads and the outer rim of the barrel extension to prevent it from twisting while torquing... Do not exceed 80lbs of torque when tightening the barrel nut...

I dont see the barrel extension alignment pin listed on Bushmaster's or any other site, do I need to call and ask for it specifically or am I missing somthing?
Thanks

Man, did you look to see if the thread job is crooked? Is the flash hider straight?  He should of chucked it up in a lathe to do the thread job...

Well, if he didn't remove the barrel from the receiver or the front sight, you are probably just looking at the front sight being twisted/bent, crooked... $10 you say, unfortunately you are right, you did get what you paid for...

Another thing to look at, check to make sure he didnt twist or bend the upper receiver in any way...

The thread job looks fine, he did put it in a  lathe, he just mounted it with the upper attached, all the scratches are from him trying to remove the brake. I dont see where he could have bent the front sight, will a new one fit, maybe if I use the same pins. could the barrel still be over tourqed?

Id suggest sending it to ADCO or someone familiar with doing barrel jobs...

 If it shot straight before the thread job and the gunsmith didn't remove the barrel nut, then its not actually possible for the alignment pin to be bent... It would be senseless to play process of elimination with parts swapping... The damn barrel could be bent from him trying to remove the original brake...

Quoted: Quoted: My GS didn't remove the barrel or front sight he just clamped the upper reciever and barrel, hack you're lucky it still groups. +1 on the possibly bent barrel. How did he remove the brake?

Since it was pressed on he had to grind a half inch off the back where it was also pinned then it looks as if he clamped the barrel and twisted it off.


If the barrel is bent or damaged It may just be cheaper for me to buy a new no-ban barrel and put it on myself that to have it fixed by ADCO, hopefully the upper is not damaged, it looks fine