The upper takes almost all the stresses of firing. Polymer lowers aren't new and seem to function fine. That said a transparent lower recieve isn't for me.
That's pretty cool, but I don't think I would want it.
Dont get me started on how much b.s. is in that ATF letter. Though it appears Sig and SB may take them to court on it.Exactly. The lower just holds the barrel from falling off and a place to hold the trigger, mag, and butt stock.
The pistol grip is nice and we use them.
The butt stock 'wrist support' the ATF on 1-16-15 issued a new ruling that if you put the butt against you shoulder you have changed the character of the item and you will have a illegal short barrel rifle using less than 16" barrel.
Dont get me started on how much b.s. is in that ATF letter. Though it appears Sig and SB may take them to court on it.