The .30-30 Win. has a 1 in 10" twist in Marlin 336 rifles. The .32 Win. Sp., and the .35 Rem., both have 1 in 16" twist rates. Why the slower twist, in these two calibers? Is it that the .32, and .35 perform better with 1 in 16" twist rates, or is it just tradition that kept them at 1 in 16" rates? Marlin chose a 1 in 10" rate for it's .30-30, over the 1 in 12" rate that Winchester .30-30's use, I suppose because they thought it performed better, in thier rifles. I understand the 1 in 16" rate in .32's was to reload cartridges with black powder, when the cartridge first came out. Did the Marlin folks ever try a faster twist?

You don't need a twist rate any faster than 1-16" for any practical weight .35 bullet.

In fact you don't need a 1-10" twist on a .30-30, either, unless you plan on shooting 220gr. bullets.

.32 cartridges were more popular 100 years ago than they are now, and I'd suspect that the 1-16" twist rate on the .32 Special was strongly influenced by the fact that 1. it was already available via existing barrel-making machinery, and 2. it costs a lot of money for little gain to find out if anything else would work better.

Remember, they didn't have computers and such and making new machinery just on speculation would be real expensive.

Actually that's been true across the industry for many years - few 'new' cartridges come into existence without being based on existing brass or bullet diameters, for example. Cuts R&D cost tremendously.

Almost certainly the .30-30s which use 1-10" twist were just make from the same stock of barrel blanks that the manufacturer uses for .30-06, etc. Same for the 1-12", that's what they had handy or could get cheap and so just stuck with it.

Economy of scale, that's really the explanation.

A faster twist generally doesn't hurt anything, too slow of a twist and bullets tumble instead of flying straight.

You can look up the Greener formula for twist rates and I'd guarantee that a .30-30 with blunt 170gr. bullets can use a rate of twist even slower yet than 1-12".

Length and weight are "kind of" related, but it's length that really sets the twist more than just pure weight. A 168HPBT is a lot longer than a 170gr. FNSP.

The 1:12 twist is enough to spin blunt pointed 190gr. bullets well (the .303 Savage used a 1:12). Believe the 1:10, as MikeG stated, was just "grand fathered" in for economic factors. The Krag used a 1:10 to spin 220gr. RN bullets, the 30-03 kept the twist becasue it used the same type bullets, and when changed to the 30-06 and it's normal lighter bullete, the twist just stayed the same.

There are those who believe (and I'm one) that a very fast twist makes cast bullet shooting more difficult, esp. if attempting standard velocity loads.

Hey fellows...
Frank Barnes in Cartridges of the World suggests that the .32 Winchester Special was introduced 13 years after the .30-30 in response to customers wanting a cartridge that would allow them to consume their stockpiled blackpowder. Winchester did some testing and this is what they came up with. A .32 caliber bore with a cartridge case that fit the existing action and a rate of twist that optimized using black powder as a propellant while negating the effects of fouling.

This is one reason many of the old, old 32 Special's bores are shot. There are several in my family that where purchased for this very reason and they are wall hangers now because not enough time was spent cleaning barrels.

Read that in COW...it's a good theory, at least it assumes the gun companies actually put some thought into the twist selection. But I wonder if they just didn't use the 32-40 twist (and production equipment) the already had on hand.

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You can look up the Greener formula for twist rates and I'd guarantee that a .30-30 with blunt 170gr. bullets can use a rate of twist even slower yet than 1-12".

MikeG,
Where can I find info on the Greener formula? YAHOO doesn't come up with anything.

"Greenhill," sorry!

All measurements in inches. Twist = 150 X bullet diameter squared / bullet length.

Bye
Jack