[andrew312nz]

I am having the same sort of issue on the PDW with the bolt carrier jamming against the hammer roller.
It seems that there is so much push in the hammer that it is jamming the carrier into the upper receiver.

It shoots fine as long as the bolt is in continuous motion, but when the empty mag catch locks in, it jamms and does not release.

When you open the lower receiver it immediately releases, as the pressure is off the bolt carrier.

Are there any solutions to this.

Cheers for any help.

Further to the above. I have replaced the standard pdw hammer roller with a sealed ball bearing. This has greatly lessened the friction, and (it appears) solved the problem.