M4 question
 

i was thinking about moding my M4 to be more of a support weapon i bought a 3000 round drum mag electronic feed. and was wondering wat would be the best build for me to be able to lay down on the trigger for a bit without damaging anything. thanks to anyone who helps me out

Don't do it. C-Mags on an M4 are douche-y. M4's weren't meant to be support weapons, and if you play in any milsims they won't let you put a c-mag on your M4 and call it a LMG.

That being said, you probably would want to get a reinforced mechbox, better piston, and gears, among other things. But I would say just run it till it breaks, and then upgrade it.

Keep the FPS low, shim it properly along with metal bushings, high speed gear set, a decent piston, ventilated piston head. And like styrak said reinforced mechbox.

For the magazine I recommend the A&K Electronic Box mag...its much cooler...

Squad AR, even without a c-mag

First of all, that's not an M4. Second of all, milsim rules still apply.

I guess it would be like that until someone invent the real cap c mag x.x

I love that IAR, had I not bought an M4 I'd make one for airsoft..... Really it would just give me an excuse to carry 20 mags lol
My advice is to stick with lowcaps, just carry more of them and hold down the trigger longer, works for me lol

Okay so basic internal upgrades assuming your M4 is TM or CA:
metal bushings
shims
Systema poly piston (NOT area 1000)
Systema silent head set for V2 gearbox
If its a CA, keep the stock spring, if it's a TM you could use an MS100 (around 340fps).

High speed gears will increase ROF, so will upgrading to a larger battery (either going from mini to large, or 8.4v to 9.6v). Personally I don't like raising the ROF past 1000rpm but you can do whatever you like :)

and that will cost??

Around 100$ for the mechbox parts.
I order my parts from ehobbyasia.com, they're cheaper than most places.