I have a M4LEP22. Love this rifle.
I got a suppressor last summer and it works fine with standard velocity ammunition. But CCI "Quiet" rounds don't seem to blow back enough to cock the hammer (usually cycles a round though).
This rifle is WAY too fun subsonic not to set it up to run this type of ammunition. Is there a spring modification to the bolt that needs to be made? And how much will shorting the barrel impact this?
*ALSO I'd like to change out to a shorter barrel to use on my SBR lower. Do I only need to buy (first find) a barrel and then swap the collar from the current upper?