Bushmaster Upper Won't fit any Bolt Carrier

[Mr Grinch]

Here's an interesting problem.

Purchased a DPMS upper, tried it with a RRA lower to find that the bolt carrier bound badly when the rails engaged in the receiver. No way I was going to shoot it that way. Had to used the assist in four or five steps to close the bolt.

Took the upper back to the shop with my bolt carrier to confirm the problem. Found that no bolt carrier fit the upper. This included all finishes available- phosphate, titanium, chrome. The receiver had a phosphate finish also. Interesting.

Closer inspection showed that while the barrel was indeed DPMS, the receiver was in fact a Bushmaster. None of us had noticed the different roll mark. One of the owners semi-accused me of swapping the receiver out myself. Well this sort of stunned me for a moment. After thinking about what this guy was saying, I began to wonder if they had tried to pass off a problem upper on me and said so.

The way all of this transpired, it made no sense for someone to risk the cash to try to get away with swapping a receiver. They quickly apologized, I returned the upper, and got my money back, making us all happy.

I was not familiar with the respective roll marks, but the real question is why would a Bushmaster receiver not accept DPMS or RRA bolt carriers? Do Bushies have different specs?

AR15.com has been down for several days, so no help there.

Thanks,

Grinch

 

[Steve Smith]

Everything should fit between manufacturers.

Many manufacturers DON'T make their own uppers...they come from a foundry (Bushy probably does because they are so big).

Obviously, something is wrong with that upper. You should make the gun store replace it.

 

[Redlg155]

A Bushy upper will fit any bolt carrier available.

Couple of questions..

1. Did you try to move the carrier to its forward position without the bolt in place?

Doing so would definitely eliminate a bolt problem if it still binds. Otherwise it could be an out of spec bolt or barrel extension.

2. Did the Bushy upper have a dry lube type finish inside of the upper? That's one way of idenifying a genuine bushy upper.

The majority of parts are interchangeable. All manufacturers out there should definitely have no problem swapping bolt carriers. The ony exception that I know of would be a Colt with a sear block.

Good Shooting
Red

 

[Bartholomew Roberts]

Are you sure you are not confusing the forge mark with the manufacturer's mark? Most of the Bushmasters I have seen only have the forge marking - though you can sometimes trace that specifically to Bushmaster in the A2 receivers.

Anyway, if it is a forge mark, then the receiver could have been manufactured by any of several AR parts companies, including DPMS.

 

[Mr Grinch]

Thanks for the replies-

First, I did return the upper and received my money back. It definitely had a DPMS barrel, but the mark on the receiver was indeed different than every other DPMS rifle on display. The receipt said "DPMS" on it.

I am not familiar with the various markings ( you can be I will educate myself before the next purchase!). My guess is that it is the "forge marking" that we are discussing, located next to the rear sight housing on the right side of the receiver. RRA has a little keyhole with three dots.

Can you describe or know of a link showing the Bushmaster forge markings? I wonder if this thing was one of those "economy models".

Yes, I took the bolt assembly apart to remove the cam and bolt as a variable. Recall that the binding occurred as soon as the bolt carrier rails engaged, long before the bolt meshed. It was as if the receiver had too small I.D. or something. The carrier alone bound in the receiver, as did six others tried by the owner. They seemed as surprised as I was.

Additionally, my bolt assembly fit in every other receiver they had in the upper inventory. I would have purchased a different upper from them, but the only config they had left that I wanted was marred excessively at several places on the barrel and was missing the allen screw from the elevation adjustment. I sort of lost confidence in these boys, and once they questioned my swapping the receiver there was no way I was going to give them my business.

The lower and the bolt assembly came from a RRA from a Wilson Combat TPR. I should point out that the TPR is a flat top rifle without a front sight, and I just wanted to add an iron sighted upper to an existing, complete rifle.

As I mentioned, I ran into the owner later, and he was very apologetic about the whole affair.

Grinch

 

[Bartholomew Roberts]

I am not familiar with the various markings ( you can be I will educate myself before the next purchase!). My guess is that it is the "forge marking" that we are discussing, located next to the rear sight housing on the right side of the receiver. RRA has a little keyhole with three dots.

Yes, the keyhole with three dots is the forge marking for Cerro Metal. RRA and Bushmaster both use their receivers on occasion. The forge can make everything from a raw receiver (a solid chunk of aluminium shaped like an AR15 upper) to a completely finished and parked AR15 upper (I think Cerro only offers them in the white and not completely finished; but Dlask offers a full range). Other forge markings are a K for Kaiser or an AF for Alcoa.

So a forge marking may not tell you much about the quality of a receiver since final quality will depend on what state it was purchased from the forge in and how well the manufacturer finishes out the final machining.

Can you describe or know of a link showing the Bushmaster forge markings?

http://www.biggerhammer.net/ar15/uppers/

 

[Mr Grinch]

I see. The supposed "Bushie" upper had a butterfly shaped (roughly speaking) in the same location.

If ar15.com ever come alive again I'll do some investigation there.

Anyone else having problems loading that site?

Thanks,

Grinch

 

[Hkmp5sd]

Put some ink on the bolt carrier and then try to insert it. It should show where the two are binding.

 

[Mr Grinch]

Put some ink on the bolt carrier and then try to insert it. It should show where the two are binding.

The first two messages I posted mention that I returned the upper the day after I discovered the problem. It was not a matter of finding where the bolt carrier bound, it was rubbing EVERYWHERE!

Grinch

 

[Hkmp5sd]

Oh sorry, I meant to do so at the gun store with the returned upper. It would be interesting to see if it was a defect or if the entire upper was the incorrect size.

 

[Mr Grinch]

I asked the guys to let me know what they find out about that receiver- I should know in a few weeks.

Kinda makes you go hmmmmmmmmmm.

Grinch

 

[yesterdaysyouth]

any chance you had a 7.62x39 bolt carrier???

 

[Mr Grinch]

No, it came out of a working high quality 5.56 upper.

You will also notice that no bolt carrier fit that particular upper. The receiver would have to be smaller than spec.

Grinch

 

[org]

Wonder if the receiver was squashed during barrel installation?

 

[Mr Grinch]

Could be, I thought that the phosphate finish might have been a little thick.

Either way, all concerned agreed that it was way too tight to fire. They are going to send it back to DPMS and find out what happened.

Grinch