No, a M4 and a M27 are the same except for looks, why is it fair to give one an unlimited ammo supply?

The m27 is not made to be a suppressing weapon like the M249. It was never made or issued with drums or box mags. It is made to use a standard capacity mag. So by using mid caps in it, you are using it 100% as the rifle was made. I have issues with RPK's with drum mags for the same reason, they are not accurate to the weapon system.

I think if you are going to use a weapon system, you should have the same basic concept of how you use it in a milsim game. That means you don't put a box mag on a M4 and call it a LMG. And a weapon that is made to run 30 round mags, and has the huge plus of it being light weight because of that, shouldn't be allowed to run box mags. You can't take every positives of a platform and change it around to avoid the negatives. I don't get to cut down the barrel of my RPK to make it CQB length and get to call it a RPK anymore, and you don't get to run high caps and negate what the M27 is.