Thanks again for all the info guys. so i just swapped out one of my 7.4 connectors and tried it in the M4. It feeds much better and the trigger response is still pretty much instant so i think that's what i'm going to use. thinking about it now, i bet i was pulling some pretty serious current on the 3S battery.
The only problem is i don't think, dispite the 25-50c rating, my 1200mAh 2s batteries will stand up too well to a half day on the field in the M4 as they were getting warm off 30-40 rounds of quick semi fire when testing. Off to hobby king again i guess! My other hobby is flying stupidly overpowered RC planes so i know a thing or two about ruining LiPos (not always on impact) and once they puff, they never entirely recover.
Sitting duck, thanks for bringing me back down to earth without making me feel to stupid, much appreciated. again from the RC hobby, 2S (7.4V) is a pretty wimpy battery, (my last plane was pulling 80 Amps on a huge 85c 4s before the wings folded in flight) so i think i have some prejudice against them that i need to unlearn for airsoft.
ill try to get some video footage to show the trigger response and post it. it runs really nice now.
Edit, i've also swapped out the spring for a M120 and locked locked it to semi. hopefully will shoot just under 400 and be my DMR