Markshar

Hi guys, recently bought a new mws cqbr. all mags seem to feed fine until I start shooting a little quicker on semi or closer to the end of the mag, I have to then put pressure at the bottom of the mag by hand, or reinsert mag to get the other shots off but I then have to do this for each shot. Seems like there’s enough gas though. I’m using Abby red gas Any ideas?? Could it be a nozzle spring related maybe? Also, it seems as if it fires okay in full auto