Gas Blow Back is cool, AEG Blow Back relies on the movement of the piston to produce a semblance of blow back by moving a small metal plate, it's not that great IMO. Kind of cool but if you're wanting the realism and kick get Gas Blow Back (but there are drawbacks to GBBR's).
As for games, weekly skirmishes are whatever. You could be a "PMC" with jeans and a tactical vest or whatever you wanted. On the other hand more involved games may have strict kit requirements (ie. must have radio, must stay in fireteam, etc.).
Sometimes they can be split up in terms of Tan vs Green, Digital vs Analogue, or whatever. Most daysim games are like tan vs green but multi day milsims might be more strict on kt requirements. Some games might even be a super strict reenacement with strict kit requirements (ie. a WWII or Vietnam simulation) these aren't too common and mostly are reenactor clubs who do this.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE