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Mausers come in all kinds of flavors, what "Mauser" do you have, that's chambered in 7.62x51?
There are 3 dimensional identical cartridges, 7.62 CETME, 7.62 NATO, and .308Win. Dimensions are where "identical" ends.

 

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Alpo, otto is a troll, don't feed the trolls!
Spain did the CETME in small ring, and large ring Mausers, it was a stop gap measure when they joined NATO, until they could get new rifles into production. It had the same "working pressure" as the 7x57. SAMCO had some good lawyers that saved their butts, after selling those small rings as .308W in a 130yr old rifle. Best case scenario, .308W would cause bolt lug setback to a point you couldn't open the bolt anymore, without a small sledge hammer. Worse case, the lugs sheared off, and you got the bolt to the face. Yes, it has happened, I have the pics of one from a fatality, he just wouldn't listen to his son.
Loading .308 cases with Savage .300 data that has the same working pressure as the 7x57, could have avoided that, and easier on the shoulder too.

 

[TRAP55]

There is a company that makes conversion kits. Convert your Mauser to use 45 ACP and 1911 magazines.

I've thought longingly of that. When I first heard about it, for an additional $150 you could send your gun in and they would do the conversion. When I was ready to have it done, they didn't do the conversions anymore. They just sold you the pieces. And I don't have the skill to rebarrel a rifle.

Oh well.

That was Rhineland, now https://centerfiresystems, but they're out of stock on everything. Easy to do once the old barrel was off. New one came with a spanner wrench for the barrel nut, to set the headspace like a Savage 110.

 

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They're 1916 actions.

Designated the FR-7, the M43 98 actions were converted to 7.62 NATO from 8mm and designated the FR-8.

 

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The 1916's were converted from 7X57.

Thus the FR-7= Fusil Reformado 7 =Converted Rifle 7mm