I have a USC with the original 16" barrel and the top notch folding stock. In the future I may go SBR, but in the mean time I was wondering if I could take the old USC thumbhole stock and cut it off to essentially make it an end cap. I reallize I need to keep the overall lenght of the gun greater than 26" which I can by leaving a good 2" on the end cap. The overall lenght would be about 27.5". Is this legal? Also If I do SBR it can I use an end cap then too? And do I need to put on the form 1 its overall lenght with just the end cap? I am a little unclear about AOW and SBR rules when it comes to end caps.