Suppressors and velocity/energy
I have a 16" M4 (DDv7). My original plan was to get a ~10" .300BLK upper to fulfill my dream of a suppressed SBR. However, financially, that's a little farther down the road than anticipated. So, in the mean time, I'm planning to trim my 5.56 barrel down (and run it with the same suppressor). Upon initial thought, I'm wanting to do this even if I managed to get a .300BLK tomorrow, since the more I think about it, the more unwieldy a suppressor can be at the end of a 16" barrel.
I already know this setup should add at least much of the pressure back that I would lose from the shorter barrel, giving me the needed dwell time that the DD mid-length prefers.
However, how does a suppressor affect ballistics? I'll probably be cutting about 4+ inches off (rough measurements put the gas block about 5 inches from the end of the barrel, so figure maybe 4.5" is my max cut) as I want the attached end of the suppressor to reside decently within the rails/handguard (purely aesthetics, but really doesn't affect the concept). The ballistics out of a 11-12" barrel that I've seen for 5.56 are decidedly weaker than expected.
SO, my question is, will the suppressor add back the lost velocity (and as a result, energy), or does it simply add back pressure and the bullet won't receive any noticeable benefit? If it does, is it similar to an actual barrel (ie a 10" barrel with 6" suppressor has virtually identical performance to a 16" barrel) or is there something lost or gained in translation?