Ran into a problem with my 22L rimfire can. I have ran a lot of rounds through it with my Walther P22, yesterday I pulled it off to put onto my AR-15 with a .22LR conversion and I could not get it to fully thread on. The P22 adapter has about 3/8 of an inch of threads and the AR has over half an inch of threads. The threads in the can that are not protected by the P22 adapter filled up with carbon and junk. I was thinking about sending the barrel to ADCO to have them cut down the amount of threads off of the AR barrel to match the length of the P22 adapter. Also I have been thinking about getting a ultra sonic cleaner any way and this would push me over the edge. Or just don't worry about it and thread it on as far as it will go and call it good. I a bit nervous about getting a half 28 tap and cleaning the threads that way. How would you fix it? Is their any one local (northern Colorado) that you would trust to cut on your barrel? Thanks for the input.