i filed my sbr paperwork, so thats done...... and when i get my stamp back, i know i have to get the trust information engraved onto the receiver....so were good there... but.. what parts do i need to convert a sig pm400 pistol to a sbr????    i know i need a new buffer tube.... but what kind?  milspec, or commercial??

all i need is the following.. correct?
1. new buffer tube...
2. stock of my choosing

do i need a commercial, or a milspec buffer tube????    this is what i am confused about.

Mil-specs are 1.185   ... . Commercials are 1.170 OD at the threads





 

Threads are the same for Mil-Spec and Commercial.

I'd buy this, and sell what I had left over on the EE.



Link

Depends on the stock you want to use...