Twist rate and bullet weight in 375 and 38-55

[andym79]

Just a curiosity, why do some reloading manuals list up to 335 grain projectiles for the 38-55 when it has a slower twist rate of 1 in 18; but not for the 375 which has a faster 1 in 12 twist?

Surely the 38-55 would struggle to stabilise the 335 grain projectile, whereas a 1 in 12 twist should easily stabilise it!

The 38-55 should top out at 260 grains due to its slow twist :unsure:

Just a curiosity, why do some reloading manuals list up to 335 grain projectiles for the 38-55 when it has a slower twist rate of 1 in 18; but not for the 375 which has a faster 1 in 12 twist?

Surely the 38-55 would struggle to stabilise the 335 grain projectile, whereas a 1 in 12 twist should easily stabilise it!

The 38-55 should top out at 260 grains due to its slow twist.

Can anyone explain, surely you can you 335 grains in a 375?

 

[Jim Watson]

I can't psychoanalyze the manual authors.
Just perhaps they thought they ought to cover the available bullets for safety's sake.
Many .38-55s are single shots and can handle greater OAL than the .375 Win lever action.
MY .38-55 has a 15" twist and shoots the 335s well.

 

[BCRider]

I'm still learning a lot about this stuff so the answers will be interesting and enlightening.

Is muzzle velocity a factor in optimum twist rate? .38-55 loads are primarily cast lead and tend to be in the 1300 to 1500 fps muzzle velocity range. .375 is a higher pressure and higher velocity round intended to start at around the 1600 fps muzzle range and go up quickly to over 2000fps using jacketed bullets or at least gas checked cast bullets.