Not to be that guy but I have one of the first batch (technically pre-production) versions of these and I ran it for a full game on Sunday (29th Oct) and can confirm that it is an impressive bit of kit for the price. It was hoping .3s at least 60m and that was in the colder weather and usual Scottish rain (Yellow Met Office Warning). I was using the Action Army AAP Drum as well as WE Glock mags and they all fed without any issues.
It is a massive improvement over their last GBB which was the MP-443 Grach under their Raptor Branding.