Ok well since SBR's are a no no here in this state the 10.5: Barrel that should arrive in the next 4-8 weeks will be a pistol project. One thing I know I will need is a heavy buffer. Do they make 5+ oz for a pistol tube? Will the gas port need to be enlarged? I am gonna have to read the muzzle break threads in depth to figure out taming the recoil issue so thoughts on that are welcome as well. Anyone know of anyone else that has done a .450 bushmaster AR pistol or SBR that might be able to give me a couple of pointers or am I the first? Hopefully I will have some pics of it around the beginning of August with a 40-45 round drum attached to it. Now that would be a great CQB setup.