.308 data for .311 bullet cause high pressure

[Bruce_in_Oz]

7.62 x 54R is a VERY "old-school" cartridge.

It was originally referred to as the "3 line" rifle.

A "line' is an archaic Russian unit of measure that just happens to be within a gnat's knacker" of 0.100", i.e. "thirty cal.

HOWEVER like its chronological stablemate, the .303, GROOVE diameter is a bit sketchy.

In "U.S. parlance, 7.62 x 54R is a "thirty calibre", albeit with "deep" rifling grooves.

The early, open / flat-based, jacketed bullets were expected to "bump-up" like the previously popular "Minie" ball. And, in fact, open / flat-based, jacketed bullets DO "bump-up' a bit when you kick them up the backside with a jolt form smokeless powder.

The Finns went all "Gucci" when they developed their TKIV sniper rifle. They took old Mosin Nagant actions and wound in tight-specced (CIP / SAAMI) .300 / .308 heavy barrel, made the thing "barrel-centric via a bedding block clamped toi the barrel and fitted a really good trigger pack. barrels . Loaded Sierra Match Kings into selected 7.62 x 54R brass and "viola", the 7.62 x 53R was born, and the set-up is a screamer.

Slug your 7.62 x 54R barrel. It should have a .300" or near as dammit bore and the rifling grooves should run out to about .313-.316".

What's a couple of thou' between friends?

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