WILL SBR U PPER FIT MY LOWER

[escooper1]

I want to buy a 10.5" 300 Blk upper for my sig m400 and I was wandering if it would fit on my Sig lower, I read on a forum for a short upper like that you need a special sbr lower, I'm new to Ar's so I don't know this stuff. But if that's the case why is the factory 300 Blk upper from Sig for that gun only a 9.5" and obviously it should work? Thanks for the help.

 

[digitalrebel80]

The special part is you have to register it on a form 1 with the atf and pay the $200 tax then wait to be approved before you install the upper on a rifle lower. If it's already a pistol lower then you are good to go without registering.

 

[VERT]

OP I am sure some of the NFA guys will be along shortly. I am not one myself. But putting an upper with a barrel less then 16" on your AR will make the gun a Short Barrel Rifle. That is a no no! The rebel above mentioned the process by which a person can do this legally.

Edit: Really a shame. I would bet there are people just learning about guns or certain types of guns that do not understand the whole NFA thing. I know people I work with are confused. The whole "sawed of shotgun" and "sig stocks" and "10.5 inch uppers" thing is all really confusing unless a person understands the laws. Because of this you know there are good, honest people out there that have done something illegal and don't even know it.

 

[Bikerdad61]

The special part is you have to register it on a form 1 with the atf and pay the $200 tax then wait to be approved before you install the upper on a rifle lower. If it's already a pistol lower then you are good to go without registering.

As long as the Butt stock is removed and you use a Pistol Buffer tube.

 

[dudley0]

Once a rifle, always a rifle.

Be positive that the lower is a pistol. Just changing the buttstock will not do it.

 

[digitalrebel80]

As long as the Butt stock is removed and you use a Pistol Buffer tube.

Only if it was a pistol first.

I said that part about a pistol lower because Sig makes the m400 in both pistol and rifle form. If it came as a pistol then you can and any other short upper you want without registering.