I have a Spike's 5.56 Nickel Boron BCG and it is going into a BCM BFH 14.5" Mid Length Upper Receiver Group. The BCG does not slide freely in the receiver and it can't even chamber a round. I'm trying to figure what in the setup is causing the problem and thought I might post here to see if I could get any help.

Here is an album showing the offending parts, how far the BCG goes in before resistance, and the wear on the upper receiver.

http://imgur.com/a/v3tJw

If anyone could provide any help with this problem it would be greatly appreciated!

Do you have another upper receiver to try the BCG in, to isolate whether it is the receiver or bolt carrier?

If not, give us a call, we'll check it in multiple receivers and send a replacement if it is the carrier that is out of spec.

I don't have another upper receiver or BCG handy but I may be able to borrow a friends. Regardless, the area of contact on the BCG seems to be the cam pin when it is turned and locked in.

When the cam pin starts to turn is about the same time your gas tube goes into the carrier key. I had a BCG the did the same thing and the gas tube was the problem. Either the tube was too wide or the key was slightly undersized. It would fully chamber if hit in, but then I would have to put a rod down the barrel and hammer the BCG back out. Just one more thing to look at. It was corrected by a new spikes gas tube. I had another company tube originally .

You unlock the bolt before you slide the carrier into your upper. If your bolt is locked it will get stuck.

Well, What was the problem? What was it? Ok, I see from his picture his bolt is not back.