How dif you get it to stay in there and not flop around?
a few ways:
aluminum strips bolted into the shell and the 10/22 body
JB weld or epoxy glue plexiglass like a skeleton around the action/receiver and barrel
extended bolt through the buffer pin
Devcon epoxy steel putty(like gum) around the action/receiver and barrel.
did you ensure that the overall length is still within BATF regulations?
not trying to be a spoil sport but even a 10/22 has a minimum length requirement just like EVERY rifle. If your mods made it too short it can lead to legal problems. they can be avoided by adding to the but pad or a longer fake suppressor to the front if it is close. else, you can submitt for the tax stamp with BATF.
No sense getting into trouble over a really cool mod