Comparing two 7x57's cases after firing

[John Wasmuth]

I saw a post on a Nosler reload forum. The guy had two cases that looked identical to what you have. He was fireforming new cases and the one on the right (in your photo) was actually 7x57 Ackley Improved - it's the cases he was creating. So maybe one of yours is that? An AI?

I was just going to write that it looked like an AI shoulder.

 

[Tundra Tiger]

Never owned an AI caliber; I almost bought an 1895 once that was .30-40 AI. But I piddle with reloading enough to know it has the look of an AI case.

 

[John Wasmuth]

Never owned an AI caliber; I almost bought an 1895 once that was .30-40 AI. But I piddle with reloading enough to know it has the look of an AI case.

I had an 8mm06 AI that was a handful of thunder. Wish I’d have kept it.

 

[fourfive8]

Here's a drawing of what is considered a 7x57 Ackely Improved chamber. You might be able to confirm that your chamber is an AI by fire forming a case at adequate pressure, +/- 45k psi, then carefully measuring the fired case. The fire formed case should be pretty close to these chamber dimensions... maybe within about .002" or so. If you confirm, with some confidence, your chamber is indeed a more or less standard AI, then you may be able to find a 7x57 AI sizing die for reloading. The next step I would recommend would be to determine the chamber length on which you base your best trim length for that chamber. Get a simple, inexpensive Sinclair chamber length plug gauge from Brownell's for that job. Of course Brownell's shows the 7mm gauge out of stock- call to get better info...