Rem. Model 550-1 .22 autoloader
I have the above rifle. It has a screw in plug at the rear of the action. The threads on the inside of the action have been slightly crossthreaded so the plug won't go in. The threads measure 20mm X 1.25 I am told. No one locally has that size tap that I've been able to locate and a special order costs around $135. Any suggestions on how to clean the inside threads without buying a special tap. Thanks.