you really like being wrong about everything:and that's on an 11" barreled CAR-15. To suppress full charge 308 ammo, in rapidfire, as well, your can has to be 14" x 2" and weigh over 1.5 lbs. That RUINS the handling of a 308, and you'd have to telescope at least 4" of the can back around the barrel. You can't do that with a lot of the 18" barreled versions of 308. So the can and barrel end up being 30" long, as vs 21" long.
If you cut the 308 barrel to 11", like the 223 can be, you get 2300 fps, so that 308 might as well be an sks, for all the "range" you will have with it. You can get a 69 gr hpbt to 2700 fps in an 11" 223, and it will reach 400 yd torsos just fine, given a scope, trigger job, and solid firing position. With any sort of cover, a ghillie made on the spot, using hammock, poncho, and local vegetation, it's easy to lay there, 300m from anybody, in a little trench you've dug, and they will never detect you, with a can mounted on the rifle. You can do a LOT of hitting, even on just cover user's heads, at that range. It's flat easy to get within 300 m of anybody, at night. If you wait until nearly dusk to fire, you will be able to easily evade them in the dark of the following night.
With a .22lr conversion, and subsoic lr's, you will be able to silently forage, remove sentries, guard dogs, etc, with brain shots to 50m. It's very easy to carry many hundreds of rounds of .22 lr, so you are most unlikely to run out of .22 ammo. Using discretion and the .22 unit, with real markmanship and tactical knowledge, you can make 100 or so rounds of 223 last for a year or more of shtf combat, and by the time you run low on 223 or .22lr, you will have recovered scores of guns, and thousands of rounds of ammo from the dead.
The suppressor is rated for for auto use and for up to 300 magnum. You don't know what a thing.
and it likes these: