I have a Grizzly gunsmithing lathe, and am chambering a Krieger heavy varmint barrel blank for my Nesika Bay single shot 6.5-284, F-Class type gun.

I have cut the thread and the tolerances are good-- action screws on etc.-- At the shoulder end of the threading I had cut a threading relief cut just behind the recoil lug area with a cutoff tool to avoid problems at the shoulder end of the threading operation. The barrel I took off the gun (shot out after 1400 rounds) was chambered by a professional gunsmith, and he did not cut a relief cut at the shoulder end of the threaded portion of the tenon-- his threads just taper up and end very nicely.

While both methods seem to work-- I am curious as to how the professional gunsmith managed to thread that tenon and have the threads end so beautifully without a threading relief cut.

Thanks in advance for any responses.