I am hoping someone on here has some experience with this question because I cannot find a good answer. I have a 300BLK pistol I recently built and have never fired. I am rethinking the pistol portion and want to do an SBR. Can I use the same lower from my pistol build and use that for my form 1? I would separate the lower from the upper until I got my tax stamp. Or, do I need to buy a new stripped lower and use that for my form 1?