Edit: Put a different BCG in and worked fine...

So I completed my first build. At least I thought I did. I started a function check and tried to chamber a round.



With no round in the chamber the BCG does what it's supposed to. With a round in the chamber it will not go into battery, and it will only go forward to about 1/4 inch short of where it should. When I try to eject the round it takes considerably more force than normal. I'm using a Ballistic Advantage barrel and a BCG out of one of my other AR's that has worked fine.

Any ideas? Thanks in advance.

How are you trying to chamber the round?

There's a good chance you're being too gentle and trying to ride the charging handle down, which is preventing the extractor claw from snapping over the extractor groove in the cartridge, so it's not fully on the bolt face, and the bolt can't close.

Correct method is to use the charging handle to lock the bolt carrier to the rear with the bolt hold-open. Put a single round into a magazine and seat the magazine. Press the bolt hold-open release.

Alternate method is to insert a magazine, and BRISKLY snap the charging handle back and release it, like a bowstring.

Turns out that BCG is garbage. Put a different BCG from one of my other rifles and it worked fine

Have you checked the headspace of the barrel in question?

If a round will not chamber, or takes a lot of force to chamber and extract, either the round is out of spec, or the headspace is too small. I had this happen to my DPMS 308 and it was headspacing. DPMS has very tight headspace and you really have to size it as small as the die/shell holder combo will go before it will chamber smoothly.

Also if you used a BCG from another rifle and it works (and I assume the entire BCG, not just the bolt carrier) then it is definitely headspacing.

What ammo?