bushmaster AR with loose barrel

[EHS]

I just sent my Bushmaster "Texas" model upper back to them to tighten and verify no other problems. Is a loose barrel something that might be a indicator of other problems to come or just usually a quality control issue? This is my first AR and just want to shoot it and not worry about "working" on it.

Thanks

[carlson1]

If that is the same AR that DPS uses I have heard they have had some problems with them. I don't know any specifics.

[PeteCamp]

I have worked on a lot of Bushmasters and a loose barrel means the 900 pound gorilla they use to tighten the barrel nuts got out of the cage.

Bushmasters usually require the most extreme methods in the AR world to loosen the barrel nut (thereby loosening the barrel). I would send it back to them.

[EHS]

Well the 900lb gorilla must have been on vacation when my AR came off the line. I did send it back. They put on a new gas tube and rings and tightened the barrel. I got it back (shipped on Bushmaster's dime both ways) and it actually hit the paper at 100 yds. I hope the gorrilla put the proper torque value this time. I want to shoot the AR not ship it back and forth. I have got to say that since the AR was actually out of warranty and how quickly they handled it (turned it in 3 days) makes me believe there might still be customer service.

[PeteCamp]

Glad you got it resolved. I would invest in an armorer's wrench. Then you won't have to ever ship it off IF it ever loosens up again. They are easy to tighten, but a booger bear to loosen!!

[Carry-a-Kimber]

They are easy to tighten, but a booger bear to loosen!!

You speak the truth brother. I had to use a 24" pipe wrench with an additional 12" conduit cheater on it to get the barrel nut off my Bushmaster 308 ORC. This was after I broke off several splines off the nut with an armorer's wrench attached to a 16" breaking bar. I called BM to make sure there was no locktite that need to be heated off and they said "No, the barrels are torqued to 80lbs." Toughest 80lbs I have everdealt with.

[Medic218]

No need to worry. Just sounds like a floating barrel to me. lol

[PeteCamp]

You guys may know this but here goes anyway. The way to loosen BM (or any other) overtight barrel nut is to put it in the freezer for an hour or more. Take it out quickly and just use your regular barrel nut wrench with the upper (or barrel) in an upper receiver fixture in a big shop vise. No breaker bars needed. I know....I didn't believe it would work either until I tried it! The barrel and nut, being steel, contract, and more importantly, expand on being taken out of the freezer, at a different rate from the aluminum upper. Neat secret. The only real trick is not letting moma see it in there.

BTW I have assembled close to 100 AR's and have never torqued any of them to 80 ft lbs. Why? Well, pull the handguards off and look. The gas tube goes through the barrel nut. There is no way mechanically for the nut to loosen to any significant degree without shearing off the gas tube - which is steel. Think it could vibrate so much as to shear the gas tube off?

[Carry-a-Kimber]

You guys may know this but here goes anyway. The way to loosen BM (or any other) overtight barrel nut is to put it in the freezer for an hour or more. Take it out quickly and just use your regular barrel nut wrench with the upper (or barrel) in an upper receiver fixture in a big shop vise. No breaker bars needed. I know....I didn't believe it would work either until I tried it! The barrel and nut, being steel, contract, and more importantly, expand on being taken out of the freezer, at a different rate from the aluminum upper. Neat secret. The only real trick is not letting moma see it in there.

BTW I have assembled close to 100 AR's and have never torqued any of them to 80 ft lbs. Why? Well, pull the handguards off and look. The gas tube goes through the barrel nut. There is no way mechanically for the nut to loosen to any significant degree without shearing off the gas tube - which is steel. Think it could vibrate so much as to shear the gas tube off?

I havetried freezing uppers with success but this one was extra stuborn. I put it in the freezer, used a heat gun, kroil, diesel, and anything else I could think of. Then I read about a guy that had to use a shop press to remove the nut off his .308 barrel and decided that good old fashioned leverage was my best option. I have built/disassembled several uppers but this one was tuff.

[Rex B]

Glad you got it resolved. I would invest in an armorer's wrench. Then you won't have to ever ship it off IF it ever loosens up again. They are easy to tighten, but a booger bear to loosen!!

You also want to get the upper receiver vise blocks. One fits the inside of the receiver, the other slips over the outside. Clamp it in a vise, then apply the armorers wrench. To get to 80 ft-lbs, you will also need a torque wrench. I used blue loctite on the threads.

Is BM's 80 ft-lbs bigger than other manufacturers 80 ft-lbs?

[goofygrin]

Perhaps they need to calibrate their torque wrench

Anyone else hate the castle nuts? I've been using them forever on car suspensions and they invariably have issues and are a pita to deal with.

[PeteCamp]

Perhaps they need to calibrate their torque wrench

Anyone else hate the castle nuts? I've been using them forever on car suspensions and they invariably have issues and are a pita to deal with.

Oh...He's calibrated all right...BM feeds him 100 pounds of meat before each batch to be torqued.

The only reason they use castle nuts is weight. I've never had a problem with them.

Thanks for reminding us about the upper receiver vice blocks RexB. I couldn't remember what they were called. A "senior moment" I guess.