Crosman 13xx 22xx threaded muzzle

Threaded muzzle adaptor for 7/16" barrel.
Thread is 1/2-20 UNF
Adapter ID is 11.2 mm - teflon tape, glue, scale or ream to fit your barrel.

You can scale by % (like 99% or 101%) to get the fit on your barrel perfect.
Print the first 5 mm or so and try the fit so you don't waste material an time on the whole thing. Scale as required after that and print the whole thing. I recommend printing with no cooling or up to 25%, vertical with the threaded end up high. Use a good size brim, and tape the brim to the bed so it can't topple over.