Home Forums Hunting & Shooting Ask The Gunwriters I have a question.

As some may have noticed, I've posted comments on a custom Mauser chambered to the 7x57 that gives pressure problems right quick like. Day before yesterday I did a trial at the range trying seating depth to see if I could find a sweet spot with the Nosler ABLR and when I got home did a little bit of measuring comparing the neck on a loaded round and on new brass against the necks on the fired brass. The average difference on five measured cased came out to .0034" Assuming, yeah I know what that means, that allowing for brass spring back probably the neck portion of the chamber is at or close to .0040". Based on that assumption, that means there is only .0020" clearance for the circumference of the neck to expand to let the bullet fly free. I guess my question os that small amount enough or should the neck portion of the chamber be slightly larger. I guess I should add that the chamber itself it also very tight. Any ideas? I really want to hunt this rifle this year but not until I get this problem sorted out.
Paul B.

Four thousandths clearance should be plenty.

When working with new brass, I'll generally check a fired case to see if a bullet will slip into the neck. I'm working with new brass for one of my .223s right now, after seeing that the necks may not be releasing the bullet as intended...and group size was unsatisfactory. I've turned case necks to reduce loaded neck diameter by about 0.002 inch. Next visit to the range should tell me whether I am correct in my conclusions.