So yeah today I picked up a couple things from Airsoft Parts for my ICS M4...
- Madbull DD MK18 Rail: This fit with pretty much no problem, really straight forward... I have to say though, the fit was EXTREMELY tight and snug, which is good I guess, since it holds up really nice.
- King Arms 10.5" Outer Barrel with Steel Chamber: This ALSO was a very very tight fit, but it fit no problems. The only problem I had was the fitting of my ICS Hop-up. I had to sand down the two sides of the ICS M4 a bit so that they would into the barrel.
- Madbull 6.03 300m Inner Barrel obviously has had no problems.
*Please note the tight fit refers to it was really tight in comparison to the original ICS barrel and stuffage :P*
So yeah in the end, the Hop-up required some modification for it to fit.