I have the same problem. more or less with a custom based on an FN commercial Mauser. It was originally chambered to the .270 Win. so I know ir should handle fairly stout 7x57 loads. I have a Winchester M70 FWT and Ruger #1a in 7x57 an either one works just fine using 7-08 data. (Loads were very carefully worked up over a long period of time Usually in the very hot summer months.) No pressure signs and brass has lasted for more that five loading with primer pockets still reasonably tight.

The throat on my custom was ordered to be the standard European length as my plan was to see what the rifle wouls do with 170 gr. round nosed bullets. I have a decent supply but my first work ups were with 140 and 150 gr. bullets to settle the rifle in and get a feel of what it may like and dislike relative to pressure. Probably gonna have to take it back to the gunsmith and have him check out that throat plus another potential problem. Check out the latest Speer manual if you haven't already done so. They have a few loads that will make you look twice. All I will add is the #1 and M70 will easily snap at the heels of the .280 Rem. with no apparent pressure problems.
Paul B.

Our forefathers did not politely protest the British.They did not vote them out of office, nor did they impeach the king,march on the capitol or ask permission for their rights. ----------------They just shot them.
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