Sorry didnt mean to barrage you,The HBAR is a heavy diameter barrel about 1lb heavier than what the military would use for a 20" barrel or 14.5" M4 type and an M203 wouldnot fit it,the M4 type is a lighter weight barrel machined to accept the M203 grenade launcher,the light weight is what is called a "pencil barrel"because it is thin like the old M16a1 barrels and is the lightest of all 3,all three are offered on post ban bushmaster rifles in the carbine leghnth you are looking for,Kurts custom and Rock River have muzzle devices that give the look of a real flash supressor it its the military look you want.and you can have a 14.5" barrel with permanent fake suppressor to bring it to the legal 16" if you are trying to get the rifle the closest you can to the specification of a real M4.The permanently open stock does not colapse,if you want the carbine look,or you can have a standard stock or the shorter stubby stock and a tubular Ace stock these are all options when you order your rifle,If you want a fake muzzle device for look get the barrel crowned with no brake on it,go to www.bushmaster.com and check out the examples they have there.A 1911 is the old US ARMY .45 AUTO my favorite,but the H&K is also a very good pistol,my buddy has a USP .45,graet pistol.