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Old October 8, 2009, 07:44 AM   #5
F. Guffey
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Join Date: July 18, 2008
Posts: 7,249
"chamber, and fire" 7.65 BM, .434 at the shoulder: 30/06, .443 at the shoulder: 308Winchester/7.62 NATO, .455 at the shoulder: The 308W/7.62 NATO is .011 thousands lager in diameter at the shoulder than the 30/06 case at the same point when measured from the head of the case, meaning when the 308W is chambered in the 30/06 the shoulder must be sized down when the bolt closes, for most when the resistance is felt they determine there is something wrong.

The 7.65X53 BM case is shorter from the head of the case to the shoulder than the 30/06 (.443) and is smaller in diameter at the shoulder (.434) by .021 thousands, this would lead me to believe there are some very large 7.65 chambers out there or some are more determined when chambering a round than I thought.

"Some rifles were converted to the NATO cartridge later in their lives. This was done by setting the barrel back and rechambering" Setting the barrel back for the the shorter chamber (308W/7.62 NATO) would require a .216 set back at least, this would just about remove the seating ring at the end of the threads, and even if this was done the bullets would be a little loose unless they designated the new chamber 7.65/08, then there would be a concern one of the 7.65/08 cartridges got in to a Spanish 7.65 Conversion.
Except for the 7x57 conversions 7.62NATO conversions got a new barrel, when the Turks converted the 7.65X53 to 8X57 they replaced the barrel and notched the receiver.

http://www.turkmauser.com/03/

F. Guffey
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