Spacemonkey

Some barrel nuts have imperial and some have metric threads. You occasionally read of people having to rethread the receiver to fit an incompatible nut. Hopefully with a search you can find out what you have, and hopefully whoever is selling what you want provides the correct information. There's a lot of hopefully's with fitting parts in airsoft. Edit to add I'm assuming it's airsoft M4 spec. https://miairsoft.proboards.com/thread/23328/m4-barrel-nut-specs

I see a few vids where the gun obviously fires but no flash, is that just the frame rate of the camera missing the flash every now and then?