I wouldn't bother with the sig brace sir. They changed the law on it now. If you shoulder it its now a felony. They knew people were using them to get SBR's around the law...it sucks as I was going to build an SBR with it.
If you really want a stock, get one and go through the 6 month wait and 200 bucks or whatever for an SBR license. Or just do it and be hush hush
I also went to Bill's this weekend, got to shoot for the first time in a long time. Shot my walther, my dads 9mm, my dads 380 and my bro's sig m400 ( i think that is what its called). Good day of shooting.