can be removable on those shorter than that IF you have paid your NFA taxes for an SBR.
What does having paid the tax stamp have anything to do with being able to take off the stock suppressor, for say cleaning or swapping another barrel over 16"?
What I am getting at is, LWRCI didn't start welding/pinning their suppressors on did they?
Anyone can buy lowers that are under 16", all you will have legally are expensive metal clubs. It's whether or not you register your LOWER to be NFA compliant as an SBR is the hitch, it has NOTHING to do with the upper.