I’ve got a weird one for you. At some point the Navy re-chambered some M-1s in 7.62 NATO. Not sure when or why, but I was awarded one while I was in the Navy. It used the same clips as an M-1 in 30-06 and has a little plastic horseshoe at the front of the magazine. You can really tell the difference in recoil. The .308 is a lot lighter.
They tried to get 30-06 power out of the shorter .308. To do so the upped the pressure and still did not quite equal the old 30-06.
If you reload then you can make the older 30-06 go up quite a bit over the .308.
Not that weird. That was essentially the Beretta BM-59, which the Italians adopted as their main battle rifle in the 50's. The did get away from the en bloc clips and modified them to take a conventional box magazine ending up with something that looked like a proto-M14.
It was to let the Navy use the new US standard ammo 7.62x51 it works .. ok but some times the invert gets dragged out of chamber which is not so good...