I have bought a 300 blackout pistol upper and am thinking about sbring it. I have not purchased a stripped lower yet. What are the next steps?. Buying a lower, cheap vs quality , paperwork for stamp etc. This is a fun build for a range toy over time. It is possible that I might leave it as a pistol and have fun with it as $$$$ is a factor also. This would be my first tax stamp if I go that route. The only things I know about stamps is it takes a long time and costs $200.00. Any help would be appreciated!