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Twist rates v powder charge

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Little confused on this matter. Thinking on getting nother barrel but want strictly a low charge ball twist in a 54 cal.

Like to load smaller charges[60 thru 80 grains 2Fg powder] as well as a hunting charge of up to 110 grains of the same.

Have read that there is a perfect twist rate for this and thought it was 1 in 70 twist but cant find where i read this.

Is there advantage to shallow v deep grooves and what about the round bottom rifling v square bottom?

Thanks in advance.

Oh and if possible id like to thumb start the patched balls and have no need for a short starter.
 
I had Douglas cut a .50 barrel for me w 1/56 twist. Shoots 50-60 gr FFg well. Previous .50 barrel was 1/66 needed 90 gr FFg to shoot well. 1/48 will work w deep grooves.

PRB barrels need rifling .010”-.012” deep in my opinion. Faster twist works better for light loads. My .54 hunting rifle has 1/70 twist w .012” grooves.
TC
 
bigted said:
Little confused on this matter. Thinking on getting nother barrel but want strictly a low charge ball twist in a 54 cal.

Like to load smaller charges[60 thru 80 grains 2Fg powder] as well as a hunting charge of up to 110 grains of the same.

Have read that there is a perfect twist rate for this and thought it was 1 in 70 twist but cant find where i read this.

Is there advantage to shallow v deep grooves and what about the round bottom rifling v square bottom?

Thanks in advance.

Oh and if possible id like to thumb start the patched balls and have no need for a short starter.



My first thoughts after reading your post was ...."It sounds like he's looking for a Thompson Center rifle.

I had good luck shooting them with light loads (60 to 70 grns ) with patched round balls.

And they will usually perform reasonably well with 90 to 100 grns as well
 
I've found the deciding factor in a barrel is the groove depth. A "faster" twist will shoot prb quite well with light to heavy charges if the grooves are at least .006" and up. I only have one rifle with .006: grooves and 1-66" twist - a .54 - and anywhere from 60 grains to 110 grains of 3F are astonishingly accurate. Loads are fairly tight. I prefer radius grooves even though they are often deeper than necessary. Square grooves may be a shade more accurate but I can't tell. Other than that one rifle, the rest of my stable goes from .010" to .016" and all shoot the same patch thicknesses.
 
It takes little rotational velocity to stabelize a round ball, but I think you are right to say there is an "optimal" velocity for any particular caliber. The Greenhill formula gives a twist of 1 in 77" as the optimum for a .54 caliber. In actual practice, for the loads you plan to use, I think anything between 66" and 75" twist rate will do what you want.
 
110 grains in with a .530 ball..., is very very stout (imho) :shocked2: I should think 80-90 grains as a proper upper end of the scale using a .530 ball.

The slower twist rate of say 1:56 with round bottom rifling will allow you to go pretty stout, up to at least 90 grains. The round bottom rifling some folks think will allow you to swap the bore between shots or every other shot or so..., and get a more complete removal of crud, as such.

As to loading with your thumb do you want good accuracy out to say 60 yards or are you looking at optimal accuracy and "thumb starting". For the first parameter you just use a thick patch and a .520 ball, but for the second method you're going to need some sort of coning done.

I target shoot and hunt with 70 grains of 3Fg in my .54 caliber 1:56 twist barrel. She does quite well and I've taken many white tails. I'd probably up the charge to 80 grains if I was going for mule deer or elk.

LD
 
I have an English 12 bore rifle, slow twist, about 1 in 100 inches, forsyth type rifling, wide shallow grooves tiny lands. It likes 4 1/2 drams of Fg with a thick patch and a greased felt wad over powder. Slow twist = large charge for large ball. Just enough spin to stabilise and heaps of power for knock down. Faster twist = lighter charge or projectile will strip.
 
hanshi said:
I've found the deciding factor in a barrel is the groove depth.

That's been my experience too. Most fast twist barrels do poorly with large charges and RB due to their shallow rifling intended for conicals. I've also learned that if you get too carried away with slow twists, you'll end up with a rifle than only likes large charges. If that's all you want to shoot, fine. Be happy with your "traditional" slow twist.

But in fact a whole, whole lot of originals including Hawkens were 1:48 twist. Kind of the skunk at the lawn party for all the slow twist pushers, but there you have it. It's high fashion for them to label the 1:48 as popularized by TC as some kind of "compromise" twist. The compromise was in TC using shallow rifling to help with conicals, not the twist rate.

I shoot a lot of reduced charges as well as heavy stuff. For me a 1:48 is indeed a compromise, but one that allows me to shoot both well. The catch is, the rifling needs to be deeper than that of a TC to do really well with big charges.

From what I can see, the old makers knew exactly what they were doing in picking 1:48. Everything I read about historic shooters points to them changing their charges up and down to suit what they were doing. "Loading for bear" being a popular description of increasing charges for more power or range. But they were also wise and used smaller charges when they didn't need to waste powder for closer ranges or smaller critters.

Whatever you choose is going to be an embarrassment to folks who feel differently. I say take a good look at the many (or few) ways you're going to use a rifle, then pick the twist rate that suits your needs. I use my rifles for all sorts of stuff, so I choose 1:48 with deeper rifling. Yeah, it's a "compromise." But so are the many chores for my rifles.
 
Back in the 70's when Douglas barrels were the most common to be found, they used 1 in 48 twist in their barrels. The one on my hand built flint rifle shoots a light accuracy load and then a heavier hunting load, but both are at the peak of accuracy in each respective powder range.

I suppose I could have loaded it beyond the 70 grain hunting accuracy load, but the groups got bigger as powder charges increased beyond that amount of powder. Have to admit I never kept increasing the charge and checking group sizes at 100 yards to find a group that would still hold within a 5 inch circle or less at 100 yards, though. Since the largest critter I ever expected to hunt with that rifle was deer, there was no reason to go above the 70 grain hunting accuracy load.

Gus
 
This is an interesting discussion.

I'm thinking of getting a barrel made (A weight 34 or 36 caliber) and really only intend to use it with RB's, and only to shoot light charges to put holes in paper. As far as I'm concerned, the lighter the charge the more I like it.

Since the velocities will be low, should I opt for a faster rate of twist? With that caliber, if someone were doing the multi-purpose thing, normally they'd get a twist rate about 130% of caliber. I'm thinking that for low charges, maybe a twist rate around 100% of caliber might be more appropriate.
 
Never approached it mathematically or spent money on experiments, but my experience sezz you probably aren't far off. My 30, 32 and 36 calibers all have 1:48 twists and they all excel with very light powder charges.

My 30 cal likes 8 grains of 3f. I've settled on 10 grains with the 32 and 12 grains with the 36. All of them shoot ragged holes at 25 yards and could probably do around an inch at 50 yards if my geezerly eyes were more cooperative. Son-in-law sure makes them speak that well, in any case.
 
For what it's worth, GreenMountain used a 1:48 twist for their .32, .36 and .40 caliber round ball barrels.

Colerain uses a 1:48 twist for their .32 thru .45 caliber round ball barrels.

At one time, Track of the Wolf offered York Rifle Barrels. The .32 thru .40 caliber roundball barrels had a 1:48 twist.
York Barrels was the successors to the Green River Rifle Works of Roosevelt Utah.

Since you are interested in a small caliber roundball barrel, I figured you might be interested in what twist some of the better known barrel companies used. :grin:
 
That's interesting, but (intuitively thinking) it doesn't seem like the same twist rate would be "best" for all those various calibers does it? I mean, the suppository rifle crowd uses VERY different twists based upon projectile weight and velocity. For example, a .22 l.r. uses a 1:16 twist, but a .223 uses a 1:9 twist. That cf round is shooting a bullet 50% heavier, but 3x faster. The actual rpm's these things spin at (15 million rpm's) is absolutely mind boggling.

I suspect the bigger companies settled on their twist rate as "good enough" rather than actually researching which one would actually be the ideal twist rate for the individual given caliber / ball weight / diameter / rpm range. thus, the decision on twist rate became one of economics more so than one of what is absolutely the "best". Since most barrels are sold to be dual purpose (field and target range), they settled on the twist so as to satisfy as many of their customers as they could, rather than truly custom build it for 1 purpose and velocity range. Of course, I have absolutely NO data to back that up. However, it makes sense, since they ARE a business, and business decisions get made for business purposes.

The other thing that makes me think a faster twist might be more appropriate, is that in a given caliber, the twist rate for rifle barrels is much much slower than the twist rate in the same caliber for pistol barrels.

Gets you to thinking doesn't it? I was going to have Charles at FCI build it for me, and he'll put in any twist I want, so that's why the inquiry. It's easier to do the research ahead of time than it is to find out you guessed wrong afterwards.
 
Zonie said:
Since you are interested in a small caliber roundball barrel, I figured you might be interested in what twist some of the better known barrel companies used. :grin:
A couple more. I have two small caliber rifles from the 1970 period.

The .30 caliber barrel is by Wm. 'Bill' Large, it has a twist rate of 1:56".

The .40 caliber barrel is by Douglas, it has a twist rate of 1:66"

Both have deep rifling. Both are very accurate at all charges large and small and at all distances I've tried them, out to 100 yards.

Spence
 
Artificer said:
Back in the 70's when Douglas barrels were the most common to be found, they used 1 in 48 twist in their barrels.
Strange. The one Douglas barrel I have, a .40 from 1970, has a twist rate of 1:66". Looking at the descriptions of all the rifle test barrels by Douglas used in the 1975 edition of the Lyman Black Powder Handbook I find 9 barrels in 5 calibers, .36, .40, .45, .50, .54. All are 1:66".

Spence
 
Do as you please but remember, we are talking about a barrel that is made for shooting roundballs.

Elongated bullets is an entirely different matter.
Elongated bullets require stabilization to prevent them from tumbling and the speed they rotate at is critical to this.

Roundballs don't tumble (and even if they did, a tumbling roundball would not be deflected from its trajectory like a elongated bullet will do) so their needs for a good twist has little or nothing to do with the Greenhill or similar formulas.

As long as the roundball is spinning fast enough to offset the deflections that are caused by imperfections in the ball, it will fly true to the target.
 
I know that the shop teacher responsible for me shooting black powder built a lovely 1/2 scale flint lock rifle for his then 8yo son. He used a surplus mauser 8mm barrel, but found the fast twist made it hard to shoot prb with accuracy and power to kill squirrels. He could load it down, I'm thinking under 5grs, but over that it stripped the rifling. He also told me it fouled quickly.

A lot goes into deciding what barrel twist a company will use, and picking the wrong one can and has caused the death of a cartridge.

The 6mm rem is balistically regarded a better cartridge than the 243win, but the 243 used a faster twist which made it more actuate with 100gr bullets. Remingtons use of the wrong twist signed the death warrant of a good cartridge.
 
Col. Batguano said:
This is an interesting discussion.

I'm thinking of getting a barrel made (A weight 34 or 36 caliber) and really only intend to use it with RB's, and only to shoot light charges to put holes in paper. As far as I'm concerned, the lighter the charge the more I like it.

Since the velocities will be low, should I opt for a faster rate of twist? With that caliber, if someone were doing the multi-purpose thing, normally they'd get a twist rate about 130% of caliber. I'm thinking that for low charges, maybe a twist rate around 100% of caliber might be more appropriate.



I got this at a gunshow. No marking on it anywhere that I can see.
Best I can tell it’s made By M. S. Hendrick, West Aurora, Illinois
The gentleman I got it from did not know anything about it other
then he liked it too. I paid a bunch for it plus bought him his lunch..

Takedown buggy rifle.
Barrel is held to the tang with a tapered pin.
The tang is drilled and taped for a peep sight.
Muzzle is turned for a loading tool.

About a .34 to .35 ish caliber, have not slugged the bore
Five groove rifling.
Rate of Twist of is 1:34
Barrel is 26 inches long, 3/4 across the flats. 41.5 overall length.
13 1/4 length of pull.
Missing it’s tang peep sight.


So that rate of twist is 1:34 like what you are thinking, yes?
I use patched .33 round ball and or a patched .314 conical
Mostly 15 grains of FFFg
It shoots well.

Picture
33-1.jpg
http://img.photobucket.com/albums/v511/Dabbletoo/33-1.jpg




William Alexander
 
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