So most every sabre defense "thundercat" lower I have seen pictures of online all were model XR15, with the SN starting with XR. Recently I just saw one that is the model is SBR15, and the SN starts with SBR.
Not knowing a lot about sabre defense, can anyone explain the difference? Is it a obvious one? SBR= short barreled rifle? If so it is a little confusing as it is currently configured as a pistol with a pistol (not sabre) upper and a pistol brace/buffer tube, obviously added what looks like somewhat recently.