I could use some advice.

I bought a complete BCM lower receiver (not a blem). I paired this with a factory built BCM upper (14.5” ELW-f with a 13” KMR rail and BCM BCG).

From a closed bolt, this setup would not permit a fully loaded PMAG (verified 30 rds, not 31) to be seated. Several different magazines tried. All magazines tried functioned in DD and Colt factory guns.

I contacted BCM and shipped the lower back to them. They eventually returned the lower, shipping it to my FFL instead of me. (Not a requirement as they are the manufacture and I already own the lower) This generated a second transferee fee.

There was no notation as to what was discovered, no communication from BCM, just the same lower returned to me. It would now seat a loaded PMAG, barely, with a closed bolt.

Yesterday was the first time I had a chance to shoot this gun. With the magazine seated on a closed bolt, and loading the gun by working the charging handle, it would fire that round, but it would not pick up the next round in the magazine. This continued to occur even as rounds were taken out of the magazine, as in it occurred with 30 rds in the magazine or even with 25 rds in the magazine.

Just to ensure it was not a magazine issue, I also had two Daniel Defense guns and a Colt 6720 with me. I tested the magazine in the other guns, no issues.

Before anyone tells me to load from an open bolt, or to download magazines, etc, this gun was intended to be my new “patrol rifle” while at work. Department policy mandates a fully loaded 30 rd magazine, and the gun to be stored in a manner referred to as “cruiser ready” which is bolt forward on an empty chamber, safety on and a magazine in the gun. Activate the charging handle to chamber a round as needed. Carrying a gun in this manner is not an issue with my personally owned DD or Colt guns. Nor is is an issue with the agency owned S&W or even the older Bushmaster guns.

As it is, I can not trust this gun for it’s intended purpose if I can not guarantee the second round will actually chamber after firing the first round.

The upper used was tested on a different lower receiver, and performed without issue. So I assume the issue is not with the upper receiver.

Any ideas of what the issue might be? I assumed initially it was a slightly out of spec lower receiver. But…?