It is a six groove barrel. I slugged the bore at the muzzle and from the chamber. It is tighter on the muzzle than from the chamber.

I have packaged the Bore slug and the Chamber slug along with the chamber casting and two fired cases to send to you. I will let you measure the slugs and tell me. I am beginning to think part of my problem is my digital caliper is a cheap and inaccurate. I am getting 0.4265 at chamber slug and 0.4245 at the muzzle, but everytime I repeat the measurement it comes back slightly different. For a measurement to be valid, the instrument should be repeatable and consistent. Once I get your feedback, I will confirm or deny I am driving myself nuts