I just finished a build, and I've got an issue:  The bolt  catch fails to grab the bolt carrier.  I tried replacing the bolt catch and the spring, to no avail.  There seems to be an angle cut on the bottom front of my BCG.  Any ideas?

What stock assembly are you using? (Buffer too) This sounds similar to an SP1 I purchased that had an A2 butt stock screw installed.  The longer length screw would prevent the carrier from going back far enough to allow the bolt catch to catch the bolt.  The bolt catch would attempt to grab the carrier, which is angled and it wouldn't hold.  It needs to catch the bolt...   HTH.

Thanks for the replies, its an A2 standard length buffer and tube, with a regular screw.  I think it might be that the magpul MOE stock doesn't need a spacer, maybe the screw is portruding too far into the tube?  A friend suggested cutting a half a loop off the recoil spring, I am not in favor of that idea.

Are you saying that you are using the MagPul Fixed Stock?

The same receiver extension is used for both the shorter earlier A1 rifle stock, and the 3/4 " longer A2 rifle stock, which is the reason for the 3/4" spacer used with the A2 fixed stock.

Is the MagPul fixed stock A1 or A2 length?

Are you saying that you are using a MagPul fixed stock without the 3/4" spacer?  That could very well explain why your boltcatch is not working.  The longer A2 stock screw used without a spacer could end up interfering with the travel of the rifle buffer.

Thanks for the replies, its an A2 standard length buffer and tube, with a regular screw.  I think it might be that the magpul MOE stock doesn't need a spacer, maybe the screw is portruding too far into the tube?  A friend suggested cutting a half a loop off the recoil spring, I am not in favor of that idea.

These MOE buttstocks? They do not need a spacer. A2 tube goes on your rifle, then these go on and screw in.

Thanks very much to everyone for the replies.  I discovered it was the screw.  What I did was measure with my calipers how much of the bolt was ahead of the catch when I pulled the charging handle as far as it would go.  I then let off pressure, and backed the screw out til I could fully engage the bolt catch as normal.  I then took the screw completely out of the tube/stock, and dremeled off a corresponding amount of the screw from the end.  I reinserted the screw, and all is well.  Very positive outcome all around, if I do say so myself.

Thank you to everyone who posted to try and help.