@UCSPanther: hav you checked out the Destroyer Carbines? Bolt action, box mag, calibre is 9mm Bergmann-Bayard (Largo). Ammo is available.
Back in the Bad Olde Days when Canadians could be trusted to shoot their evil "semi-automatic machine-guns", I chrono'd the same box of shells, a very hot load, through an M1911A1 and through a Reising Model 50 SMG. Same shells came out at 200 ft/sec faster through the Reising than they came out of the Colt. Sonic-level performance from a 225-grain hard-cast bullet is impressive and not to be sneezed at.
What we really NEED for a "pure-fun gun" would be a Reising Model 60: strict semi-auto and very reliable. Too bad the ATF forced them out of production "just in case", many years ago.
For a 7.62x25 conversion, there would be a lot of jiggery-pokery and you would need a barrel with about a 16-inch twist for that 86-grain bullet to stabilise reliably. Standard twist in ALL .303 barrels is 10-inch.
Some of the early 7.62NATO conversions of the Number 4 Rifle didn't even bother to swap extractors. I have seen and used a couple which worked fine. You can use a standard extractor, just thin the inside of the thing where it butts onto the bolt-head, perhaps thin the bolthead just a tad at the sam spot. Extractor sits over to your left a bit farther, presses the extracted casing against the sidewall of the receiver, tips the thing out long before it gets to the ejector screw. Analyse the action of the rifle carefully and slowly before spending tons of money: Lee-Enfields are VERY versatile.
Hope this helps.
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