Bolt carrier group getting stuck in buffer tube

[red_star_republic]

I just bought this Spike's/Adams Arms "New" gas piston upper from another member and the bolt carrier group is getting jammed in the buffer tube.

I've had to but stroke it on the ground to get it to slide forward

This is my first time dabbling with "after market" gas piston uppers so I was wondering if there is anything I can do?

Found a couple of links during a search but it still doesn't make since that my LWRC lower/buffer tube would be out of spec - right?

Any help would be appreciated

[Tzintzuntzan]

Is this a conversion kit or a factory built AA upper? You should probably call one of those two places and see if they can get this sorted out for you since it is not normal. Then again how exactly is the BCG getting stuck in the buffer tube? Is it completely in the tube or is it sticking out a short distance?

[red_star_republic]

Limited run Spikes/AA dedicated upper.

I can pull the entire bolt carrier group back into the tube but it will seize.

[Redbeardsong]

Sounds like your buffer tube may not be threaded in far enough to keep the retainer pin from popping up, causing it to catch the bolt carrier when it goes past it.

[Tzintzuntzan]

Does the lower work with other uppers? If not does the upper work on a lower that's known to work properly?

[JSantoro]

Is it a billet upper, by any chance? Does the lower have a BAD lever, or something similar bolted on to a standard bolt catch?

The few times I've seen that sort of thing happen, and couldn't be attributed to anything else wonky with the RE or buffer retaining pin, it was because the thicker walls of a billet ANYthing, coupled with the extra thickness added to the back of a bolt catch, meant that the outer diameter of the channel in which the BCG travles impinged on the back of the bolt catch.

That pushed the ping-pong paddle outboard, which raised the bolt catch inside, and didn't allow for the control feature to be pressed to allow for release because it had no room to move back inboard. HOW stuck the BCG was depended upon on how much the catch was actually raised, internally. Sometimes mortaring would get it past, but the gun wouldn't fully cycle on a full mag, OR the thing just stayed stuck back until one or both pins of the lower were popped, which of course pulled the BCG upward enough to shoot forward.

Seen that with a LaRue Stealth upper, a Mega, and can't remember the other....but once any misalignments and loose or out-of-spec parts were eliminated, it was billet uppers + lowers that included some jewjaw that acted as an extension or other add-on feature that effectively added material to the back of the ping-pong paddle.

[bigoldglock]

I will always try and troubleshoot the easiest and obvious first. I it possible that the buffer tube is bent or malformed in a spot, which could cause the bind. Replacing the tube would be my first go, if you have already checked that the retainer pin is not popping up too far causing the jam. Any unusual marks or marring anywhere?