I have cut hundreds of chokes over the years, for myself and for my clients. I insert an adjustable reamer from the breech end and place a bushing in the bore and another in the chamber. The barrels are held in a milling vise mounted on the compound of my lathe. I flood the bore with coolant and use the power feed on the lathe to move the barrels over the reamer. The set up is rigid enough but the reality is when the reamer is bushed it wants to stay true to the bore. Reamers by nature want to center themselves unlike an endmill which is happy to cut on just a portion of its cutting surface. I like the power feed on the lathe. You can set it fast to remove the majority of the material and very slow for the final pass which leaves a very nice surface finish. I know a very good gunsmith who cuts chokes by hand with a large tap wrench. It is not for me but the gentleman has been getting excellent results with his method for many decades.

I agree with Chuck, few machinist are good gunsmiths and vice versa.

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