Will a 280 Ackley Improved reamer clean up a 7x57 chamber? Thanks

Yes even a basic 280 will clean the chamber. The issue is the neck dia listed on some sources for the 7x57 is a touch larger. Something like .325 vs .315 for the 280. This has been argued on here numerous times as to what a 7x57 neck is cut too. I've cut any number of 7x57s to my 280PDK which is built on 280Rem brass. I have never seen a line on my necks. If you get one and it bothers you recut the neck.

Yes it will and I have one made that way, and I have the reamer. It does not have a neck line.

Rechamber a military 7x57 to a SAAMI-spec 280 and I promise you will have a line on the neck. I used a neck reamer to correct that. Of course, it is not often that one has to re-chamber a 7x57 to 280 today so not as common an occurence. Regards, Bill.

Bill I'll admit to never rechambering a Mil 7x57 to 280. Is the mil and commercial 7x57s neck different dia?

I never recommend to re-chamber a military 7mm to a 280 Ack; I don't do it; I want a chrome moly steel barrel with a thicker shank; not an old military, carbon steel barrel. Reason?; usually with wildcats, people like to stoke them up with powder; I know I do.
Mine was done on a commercial barrel that already had a 7mm chamber in it; no issues.

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usually with wildcats, people like to stoke them up with powder;

Really???? OK I will admit in writing that when I first built my 280PDK wildcat I pushed it. What was the purpose if it couldn't blow the doors of a 7mag right. So yes 1 fire forming load 2 max loads and primer pocket was history. I had winter loads that I couldn't use in the heat of the summer in TX. Fine line between losing the pocket in a couple loads and blowing the primer.

So about 25 yrs ago I dropped back. Tossing the brass after 5-6 reloads, saving powder and only giving up a few FPS made a lot more sense. Must have been the difference between a 30 yr old and 40.

Besides the best thing about a wildcat is being different and having something to talk about around the campfire.

I tend to back off on loads nowadays that, 20 or 30 years ago, I would have laughed at people for wasting bullets in. I guess I don't need as much speed as I used to. Yeah, fine line between a loose primer pocket and a blown one, but the fun is (was) getting as close as you can to it.

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Originally posted by ramrod340:
Bill I'll admit to never rechambering a Mil 7x57 to 280. Is the mil and commercial 7x57s neck different dia?

Paul,
The CIP specs for the 7x57 call for a neck dia of .3217 while the 280 SAAMI spec is 3156 (these measurements at the mouth). I don't know what the SAAMI spec is on the 7x57 without looking it up.
In truth, the step did no real harm but was unsightly so I had to resam it out. Regards, Bill

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Paul,The CIP specs for the 7x57 call for a neck dia of .3217 while the 280 SAAMI spec is 3156 (these measurements at the mouth). I don't know what the SAAMI spec is on the 7x57 without looking it up.In truth, the step did no real harm but was unsightly so I had to resam it out. Regards, Bill

Yep appearance only.

To be honest I might need to mic the neck on my 280 reamer. I "ASSUMED is was cut to 280 SAAMI Spec. But I wouldn't bet more than a on it.