Yeah I know,"There's a ton of topics already pertaining to this subject." But none of the one's I searched for could concretly answer my questions.
So: I'm wanting to upgrade my ICS M4, all I really want to do is increase the FPS cause it's already accurate. I'm not sure which spring I should get though, or if I should just buy a kit. If I get a new spring I know'll I'll need new bushings but I need advice on which ones I should get. Or if I should bother upgrading my gat at all.
Please give advice if you have it, or helpfull, previous topics on this would be usefull. Thank you.
A stock ICS M4 will handle a M120 spring--grease the spring really well with Sta-Lube white lilthium grease (you can get this at any auto parts store--and its much better than the Systema or any airsoft brand, much cheaper, and you get more than you'll ever use). It takes only about 5 minutes to change the spring.
Slide the upper mechbox out; lay it flat with the rear hole to your left, remove all the screws and when taking out the last one, apply some downward pressure onto the mechbox so it doesn't "spring apart,' insert a skinny screw driver or punch into the hole of the mechbox...applying downward pressue, remove the top of the mechbox and then release the spring slowly. Use the same procedure with a screwdriver or puch when inserting your new spring.
The gears and motor won't pull a M130 spring well...you'll end up with a lot of headaches. I don't recommend it unless you're prepared to uprgrade the entire internals.
Wait until your nylon bushings wear out before changing them. 7mm bearings will do a great job. Don't use a battery higher than 9.6V...the ICS wirinig isn't designed for high voltage batteries...they'll corode quickly.
If you want to imporve your rate of fire, change the motor to a TM, Classic Army or Systema. Knock out the tab inside the stock (long screw driver and mallet) so you can use a large 9.6V battery.
The above recommendation is based on trial and error of messing around with over a dozen ICS M4's.