Israeli Mauser 7.62 (308) Twist Rate

[Bruce_in_Oz]

With the relatively short 144-148gn "NATO" bullet launched from a 7.62 NATO case, a 1:14" twist in a K-98-length barrel will be fast enough to stabilize it.

HOWEVER, with longer projectiles, like any of the 7.62 tracers or "match" bullets, things could get a bit "wobbly", hence the "general" standard for that cartridge being 1:12" twist.

On the other hand, another potential concern, that of stability at "Arctic" temperatures, (somewhat denser air), was unlikely to be major concern to the Israelis.

The early models of the Australian "Omark" Mod 44 target rifles had relatively long 1:14" twist barrels and seemed to shoot OK with the Oz 144gn bullet. Well, at least here in sunny Queensland........

The "standard' twist for the original .30-06 was 1:10", a carry-over from the '03 with its very long, 220gn "torpedo" bullet.

.303 barrels have a 1:10 twist because the Mk7 bullet is pretty much the same LENGTH as the earlier 200gn bullet of the Mk6 and earlier variants.

It is the LENGTH that determines spin rate, and thus twist rate for a given velocity.

Note that oddballs like the .300 Whisper and its derivatives require VERY tight twists to stabilize their long, heavy bullets at SUBSONIC launch velocities. For starters, you do NOT want a "wobbly" bullet bouncing off the baffles of your expensive "muffler", do you?

A 180gn VLD bullet that cheerfully stabilizes in, say, a properly stoked .300Win Mag with a 1:12" twist barrel, needs to be doing similar RPMs at ANY velocity to fly straight. Thus, the ludicrously tight twist in the .300 Whisper.

All of that aside, most, if not all of the barrels for the Israeli 7.62 K-98s appear to be of Belgian origin, FN did a significant number of these barrels, if not the complete conversions.