Why is 32 cal different

[braintan]

I admit to knowing nothing so i'm confused about why most round ball barrels come in slower twists but the 32s are apparently only available in fast twist.

 

[cowpoke1955]

The .32 Traditions Crockett and the .32 Pedersoli Frontier/Blue Ridge are both 1 in 48" twist. This is a middle of the road rate of twist, not fast. In fact, most of Traditions and all of the Pedersoli Frontier/Blue Ridges, except the .54 cal., are 1 in 48".

 

[Protrucker]

It was explained to me that, "the smaller the caliber, the faster the twist rate needs to be." It supposedly has something to do with the surface area of the ball. :hmm:

I'm sure someone with more knowledge than me will add the this. :redface:

 

[BrownBear]

There's evidently a formula for figgerin it out. Several times recently someone has posted both the formula and the theoretical ideal twist rates for various calibers. In general though, the smaller the bore, the faster the twist and the larger the bore the slower.

In my experience with the Crockett 32 and a CVA 36, it's hard to believe that their twists aren't "right" just like they are, no matter what the forumla says.

 

[boar]

The biger balls are easier to stablize in a slow twist. Half turn usually. My .54 34 inch barrel 1-70. Smaller balls needs a faster twist to stablize. Usualy 1-48. Dilly

 

[Evan Ebersole]

My 32cal is 1 in 72
my 36cal is 1 in 66
my 40cal is 1 in 66
they all shoot tight groups with any load from 20 to 60grs. for the 32 and 36 the 40cal. 20 to 80 grs.

 

[braintan]

Lost in time,
where did you get that barrel?

 

[Zonie]

"Why is 32 cal different"?
_________________________

Cause it is a pea rifle. :grin:

At least that's how George Ruxton described it in his description of a hunt with some Chippewas in 1843.
"...As we walked silently on in Indian file, a black squirrel would start from a log where it had been enjoying a breakfast of nuts and, chuck-chucking at our approach, dart up the body of a tree, where, out of reach it would face us, chattering and beating the bark with its tail. Joe, an Indian boy who accompanied us, soon had his belt strung with them, tumbling them down with his pea rifle, seldom failing to bore their heads with his bullet." (p57, RUXTON OF THE ROCKIES , Clyde and Mae Reed Porter, University of Oklahoma Press 1950).

OK, I don't know for certain that he was writing about a .32 caliber rifle but that size sure does look to be about the size of a pea, don't you think?

Back on topic, yes the smaller calibers use a faster twist. It is common for barrel makers to use a 1:48 twist for their .36 and .32 caliber barrels. It has to do with the angular velocity of rotation.

 

[flaming canvas]

"Why is 32 cal different"?
_________________________



Back on topic, yes the smaller calibers use a faster twist. It is common for barrel makers to use a 1:48 twist for their .36 and .32 caliber barrels. It has to do with the angular velocity of rotation.

Angular velocity or angular momentum? The angular velocity wouldn't be affected by the diameter of the ball, but the larger ball will have a greater angular momentum due to increased mass and a longer moment.

 

[MikeChapin]

Most barrel makers use a 1:48 twist for .40, .36 and .32. From what I have heard, faster twist stabilizes the ball better with smaller loads. That's why you see pistol barrels with 1:28 or tighter even in the larger calibers.

I remember seeing a chart from Zonie or Paul that showed the ideal twist for each caliber. You may find it on a search or they might chime in here.

 

[Walks Alone]

32 rifles have also come standard with 1:28 or 1:30 twist.

 

[LRB]

As far as accuracy, most often the powder charge can be adjusted to most any twist, irregardless of caliber, although you may not achieve the power you want, or you may have to use a heavier charge than you like, to get the desired accuracy. Most common barrels have a twist for each given caliber, that is intended to give good accuracy for target, and also good accuracy with heavier charges for hunting. The intent is to put the twist in the middle ground in order to cover both aspects of shooting. If you are a specialty shooter, you may want a custom twist that is tailored to your shooting desires. For instance, a target shooter only, may not want the recoil of a hunting load in order to get the desired degree of accuracy he may want, so he might go for a little faster twist than the recommended standard, which in theory, would require less powder, and vise-versa for the hunter only. He may want a slower than recommended twist, in order to get good accuracy at a higher velocity than the target shooter needs.

 

[BrownBear]

Good point on the velocities Wick. Both my 32 and my 36 are small game guns intended to put meat on the table. I kept reducing charges till the "crack" of supersonic travel disappeared, and got jumps in accuracy at the same time. I've never even tried fast loads in either one.

 

[braintan]

"Why is 32 cal different"?
_________________________



Back on topic, yes the smaller calibers use a faster twist. It is common for barrel makers to use a 1:48 twist for their .36 and .32 caliber barrels. It has to do with the angular velocity of rotation.

Angular velocity or angular momentum? The angular velocity wouldn't be affected by the diameter of the ball, but the larger ball will have a greater angular momentum due to increased mass and a longer moment.

Now that word "angular" is familiar. Thats what most of my shots seem to do is angle off somewhere. :rotf:
Seriously, I appreciate the responses. You guys are really helpful. I'm gettin ready to try building a rifle and want to be as informed as posible. Thanks
tim

 

[Zonie]

I probably should have said "circumferential velocity" than angular velocity.

Just for the H of it, I used my Lyman Black Powder Handbook to come up with some velocities that could be considered rather typical of a mid power load in several various calibers.
These coupled with the ball diameter and rate of twist gave some surface velocities for the outside diameter of the balls at their largest diameters.

A .32 dia ball traveling at 1880 FPS in a 1:48 twist barrel has a surface velocity of 472 inches/second.

A .50 dia. ball traveling at 1570 FPS in a 1:60 twist barrel has a surface velocity of 477 inches/second.

A .58 dia ball traveling at 1460 FPS in a 1:70 twist barrel has a surface velocity of 456 inches/second.

I don't know what all of this really means but my guess is a surface velocity in the neighborhood of 460 inches/second will do a good job of stabilizing a roundball. :hmm:

Another thought is that a roundball really can't "keyhole" because there is no "long" side on a ball so as long as it's spinning at a pretty high speed and isn't deflected by things like burned thru or ripped patches it will maintain it's line of flight very well as it flys to the target.

 

[MikeChapin]

32 rifles have also come standard with 1:28 or 1:30 twist.

Yes. The CVA Squirrel Rifle and the T\C Seneca and Cherokee all had those faster twist barrels. The two I have used, the CVA and the Seneca, have both been tack drivers with the right loads.

 

[Rat Trapper]

When hunting with the 32 & 36 cal rifles less is more. High vel to obtain accuracy is not desired if one plans to eat those squirrels and rabbits. A faster twist like the 1 in 30 used in the TC Cherokee will allow you to use less powder to get the accuracy. Less powder means less damage to what you plan to eat after you shot it.

 

[410-er]

Thats what I thought,Rat.1:30 for lower powder charges.