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magnum05 12-06-2012 10:59 PM

Upper reciever problems, need help!!! smh!!!!
okay so i have a bush master carbine that is "carbon" and when i say carbon i mean its not the usual forged aluminum.. i bought a yhm free float and the barrel nut that came with the yhm is a tad smaller than the barrel nut that was on the with that in mind are there different sized barrel nuts or is it just because it a carbon receiver and not the aluminum??? My next question is should i just buy a new receiver or try a different barrel nut and will my barrel fit in a new different receiver?? im so pissed, i was excited to put this bushy together and now im at a dead end with this damn barrel nut b.s.

You guys help me a lot so far i could only think to come here and hope for the best resolution!! Any good receivers around $100??? i have a few in mind like yhm, del-ton, rra but just figured id ask

willfully armed 12-06-2012 11:47 PM

Barrel nut threads should be all the same on the ar15 platform, unless Bushmaster pulled a proprietary FU, do you have a dial caliper? Measure inside radius of the nuts.

Be sure to lubricate the threads with good oil AFTER cleaning them WELL.

Torquing to 30#, back of slightly, then to the next keyhole not exceeding 80#.

c3shooter 12-06-2012 11:51 PM

You have a CARbon 15- and the design is a smidge different from the standard AR. Parts may not fit.

Jpyle 12-07-2012 12:14 AM

When you say that the barrel nut is smaller do you mean that it does not allow the barrel to be secured to the receiver or that the outside diameter of the barrel nut is smaller than the one supplied. Reason I ask is that the free float tube mounts to the supplied YHM barrel nut and the diameter may be different. The 2 barrel nuts are not interchangeable so there is no need for them to be of similar size.

dickpalmer 12-07-2012 12:31 AM

Call Bushmaster tomorrow. They will have some info for you. If the barrel nut won't thread on, you can't use it obviously. They may have a recommendation for you.

magnum05 12-07-2012 12:41 AM

The barrel nut that came with yhm free float is a smaller diameter than the barrel nut/delta ring that was on the ar to secure to barrel to the receiver..

Gatoragn 12-07-2012 01:22 AM

Palmetto State Armory has stripped uppers on tonight for $54.99. Regular price is 99.99 + shipping. This is a great stripped upper.

magnum05 12-07-2012 01:33 AM

Yeah I seen that but they don't have m4 feed ramps and my barrel has them so wasn't sure if I could use that

Gatoragn 12-07-2012 01:43 AM


Originally Posted by magnum05
Yeah I seen that but they don't have m4 feed ramps and my barrel has them so wasn't sure if I could use that

Good catch.

magnum05 12-07-2012 04:10 PM

I measured both barrel nuts and it's a .050 difference, so im going to stick the yhm barrel nut which is a smalller I.d than the original nut in a lathe and take down the i.d of the threads .025 and see what happens..thanks for the help guys

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