Twist Questions

[Nor'Easter]

Narrow grooves, wide lands, some careful relieving at the muzzle. Unlike today’s funneling, many originals haves short section at the muzzle where both the lands and grooves are “funneled” and appear just like the rest of the barrel but are about 0.010 to 0.020” wider at the muzzle. No crown, no countersink. Often folks take a caliber measurement at the muzzle on originals but it’s bigger there than 2” down.

This is NOT due to muzzlewear from the ramrod. If it was the lands would be worn down and groove depth would look minimal.

Dave, was the muzzle "funneling" done with the rifling equipment or by hand?

 

[chorizo]

This gets to the above point within this thread: Random photos of famous ML percussion/flint guns, or rather guns owned by either famous people or during famous events

I have pulled some salient posts and pics from it.

Quote from @Herb .....the Liver-Eating Johnson Hawken, I handled, measured and photographed it at the Cody Museum in December 2018. The barrel is 1.3 inches wide at the snail and 1.218 at the muzzle. The muzzle was .583 in diameter. I ran sized bore-gauges down the bore (which was good) and it measured .537, or .54 caliber. All Hawkens I have seen have some muzzle relief. The curator puts a tapered bore-gauge into the muzzle (there was one on the table) and they think that is the bore. It ain't. I gave the Curator the correct bore diameter, which he ignored. I measured the twist at one inch in 50.8 inches, which is really one in 48 inches. Notice the patina of the relieved bore.




The first photo is the 56 cal Hawken (as marked on the description at the museum) owned by "Liver Eating" Johnson. Bottom rifle in picture of 3. Blow up the picture to read caption under rifle. It can be found at the Cody Museum in Cody Wyoming. Note the massive amount of metal around the bore!

 

[Notchy Bob]

So here are some examples of rifling old and new...,

Here is a hand cut barrel. Note how thin the grooves, and that there are an odd number of grooves because the land opposite the groove was needed to support the shaft holding the cutting bit...

View attachment 182482

Here is another antique. Again very thin rifling but an even number of grooves..., yet this is hand cut for sure....,
How did the barrel maker achieve this ???

View attachment 182483

The cutting machine used for the above barrel has grooves opposite while being a hand cutting machine, because (I'm told) the machine had two cutting bits, opposite of each other, thus they cut at the same time and supported each other while cutting. Saved manufacturing time too, reducing rifling time by almost half.

Here is another barrel done with a double cutter by hand...

View attachment 182484

Here is a modern cut barrel.... NOTE the grooves are now wider than the lands, a completer reversal of the situation in the originals

View attachment 182486

Now here is round bottom rifling. NOTE how although the grooves are not quite as wide as the lands, they are also rounded at the bottom. My personal rifle has rifling done this way, It's a lot easier to do, I'm told by a machinist, as it reduces wear on the cutting tool edge, and companies market this as easier to keep clean.

View attachment 182487


Here's a machine cut barrel with grooves very much wider, than the lands.....

View attachment 182489

Here's a machine cut barrel where the rifling is a bit closer in similarity to it's antique ancestors having grooves a bit thinner than the lands... but still wider than the antiques... these also look really "shallow" to me, and I don't know if this would be good for a round ball ....

View attachment 182488

LD

Epic post, @Loyalist Dave ! Very informative and extraordinarily well illustrated.

Notchy Bob

 

[Resolve]

Thanks, folks, for all the good info. I learned more info on this subject in this thread than I have in my entire BP career. Like I said, now I get it.

 

[Absoroka]

A couple of thoughts. On your question regarding barrel length, you will lose some velocity as the barrel gets shorter for a given powder charge. It is not hugely significant until you get below 28 inches, but it can affect your point of impact, particularly at longer ranges. On charges and twist, I have a 32 caliber flintlock with a 40 inch, 1 in 66 twist barrel. It shoots with decent accuracy using smaller charges but the group continues to tighten up to a ball weight charge. This is a heavy charge for the caliber but is a tack driver. The best target it ever shot was at 50 yards off of cross sticks and was a 50-4X on the NMLRA small six bull target. It will knock over silhouettes out to 75 yards, largely due to the velocity. My other 32 caliber with a 28 inch barrel that shoots 25 grains of 3F is accurate but carries little energy beyond 25 yards. I think the suggestion of a 40 caliber for your stated purposes is a good one.

 

[Resolve]

A couple of thoughts. On your question regarding barrel length, you will lose some velocity as the barrel gets shorter for a given powder charge. It is not hugely significant until you get below 28 inches, but it can affect your point of impact, particularly at longer ranges. On charges and twist, I have a 32 caliber flintlock with a 40 inch, 1 in 66 twist barrel. It shoots with decent accuracy using smaller charges but the group continues to tighten up to a ball weight charge. This is a heavy charge for the caliber but is a tack driver. The best target it ever shot was at 50 yards off of cross sticks and was a 50-4X on the NMLRA small six bull target. It will knock over silhouettes out to 75 yards, largely due to the velocity. My other 32 caliber with a 28 inch barrel that shoots 25 grains of 3F is accurate but carries little energy beyond 25 yards. I think the suggestion of a 40 caliber for your stated purposes is a good one.

Thanks Absoroka. So I'm guessing those 24" factory hunting carbines I see might not have the velocity to do the job at longer ranges? Have no plans on getting one or hunting, just curious.
R

 

[hanshi]

Resolve, I think your questions have been answered in the previous posts. I have little to add, but will go over the main points. Except for the very fast twists, prb will do well in most any twist....IF.

1. The grooves are deep enough, say, around .006", preferably deeper.
2. Smaller calibers generally get the faster: 1-48" twist but still need good rifling grooves.
3. Longer barrels generally give higher velocities, but...
...it often happens that as powder charges go up velocity will drop at some point then continue to rise. Speed increases with more powder are NOT always linear.
4. Sometimes the shorter barrel will be faster.
5. Black powder gives limited velocities that seldom go above the lower 2,000s. 2,200 fps can
be reached in some calibers but not a lot faster.
6. Tighter prb loads are often more accurate with higher velocities but not always.
7. Even very fast twists can give good prb performance with deeper grooves at certain speed levels.

 

[Dale Allen Raby]

As a matter of fact..., I've seen a vintage TC Hawken manual, from I think their first or second year selling Hawkens. They included load data for double, patched round ball for their .45. The shooter was to load the rifle with a patched .440 round ball, and then add another patched round ball on top of that, seated against the first round ball, of course.

I could never find out if that was TC's idea..., that they didn't think the .440 ball had enough mass..., or if they had been told that none of the guys buying the Hawkens would think the .440 ball by itself would work on deer, so the added procedure and loading data was there to help sell the .45's. It was discontinued when it became pretty much a nation wide law that the muzzleloader couldn't launch more than one projectile from a barrel at a deer..., and perhaps some folks that knew better, told TC that two .440 ball weren't necessary.

LD

I've actually tried this with my .45 Hawken. At fifty yards, the balls hit one directly above the other about four inches apart. It's an illegal hunting load in Wisconsin, but it does work after a fashion. I see no real need for it unless one wants to try it on dangerous game of some sort.

 

[zimmerstutzen]

The width of the grooves affects how well the rifling grabs the patched ball. My target barrel was a sort of combination of the second from the bottom and the third from the bottom. In my opinion, the wide round bottom groove barrels are best, but the tight curve of that "round arc" is too small for the wide grooves I am talking about. Harry Pope designed rifling with very wide round bottom rifling by using a cutter that had an arc that was of a curve that was twice as large as the bore curve. The result was that the corners of the groove were actually deeper than the middle of the groove. About 1980 Hoppy Hopkins cut a special rifle bore for me based in part on Harry Pope's idea. but the wide grooves were like an oval laid on it's side. the grooves were four or 5 times wider then the lands. Looking down the barrel lands looked like rails for the patched ball to ride on. The oval grooves left no corners for fouling to accumulate in. Even with open sights, I shot many one hole 45 caliber groups with it at 75 yds and a few at 100. The twist was 1;66 or 1;72 ( just don't recall) but my target load was 65 grains of 3f Goex and a cotton flannel patch with only spit for lube..

 

[zimmerstutzen]

Dave, was the muzzle "funneling" done with the rifling equipment or by hand?

You have to question the effect of funneling on fine accuracy. If it has no effect, there would be no benefit to false muzzles and matches would have no reason to exclude false muzzle guns from competition.

 

[Rifleman1776]

Does barrel length affect the accuracy more so in a slower or faster twist?

I will say 'no', not a factor. The late Bob Munden, a famous six-gun sharp shooter, once demonstrated accuracy using an unmentionable in .38 special with a two inch barrel. He consistently could hit an 8" target with it at 300 yards offhand. There is a well known maker of smooth fowlers who can shoot his with rifle accuracy that others cannot match. I have long suspected he has several inches of rifling at the bottom of the barrel and that is enough to give him his rifle like accuracy.

 

[Uncle Miltie]

Good morning from the Verde River,

Some questions on rifling twist (in rifles, not pistols or revolvers). Right or wrong, in the past the extent of my knowledge regarding rifling twists was:

• 1:66/1:56 were slow twists and best for patched round ball.
• 1:48 was an all-purpose faster twist which shot both round balls and conicals effectively.
• 1:32/1:28 and lower were very fast twists used for sabots.

On looking at past posts I am seeing that it isn’t as simple as that, there are more variables involved. So, I have some questions.

• Does barrel length affect the accuracy more so in a slower or faster twist?
• Does the 1:66 twist require a larger load for effective accuracy?
• If you had 2 barrels in the same caliber and length; one a 1:28 and the other a 1:48 twist, would the 1:48 require a larger charge for effective accuracy?
• If you had 2 barrels in the same caliber and twist; one 28” long and one 36” long, would they both require the same charge for effective accuracy?

Let me provide some background here that might help explain what I’m driving at. Soon I will be purchasing another rifle as I need to start shooting a lower caliber. It will not be used for hunting, mainly just plinking, and shooting sheet silhouettes at 25 to 75 yards. I would prefer it to be 32, 36, or 40 caliber. Possibly even 45. I like shooting smaller target loads. For what I am doing effective accuracy to me is hitting a clay pigeon at 50 yards. As I do not plan on going to Innsbruck to compete in any Olympic Biathalons I don’t need one-inch groups at 100 yards.

Thanks for any info,

R

A book everyone should read regarding barrel twist, etc...

 

[chorizo]

Thanks Absoroka. So I'm guessing those 24" factory hunting carbines I see might not have the velocity to do the job at longer ranges? Have no plans on getting one or hunting, just curious.
R

Not true. Depends on how you load them and with what. Very common misperception, kind of like the old "you will shoot you shoulder into a taco" misperception for heavy loads so oft repeated on this forum.

I am getting excellent velocity numbers on my 21/22" carbines.

Do a search and you can se my choreographed results.

Also this calculator can tell you lots on that very subject and I have found it to be pretty spot on.

https://www.p-max.uk/cgi-bin/black_powder.cgi

 

[DixieTexian]

Here's my take on the matter. Take it for what you paid for it, as it's only my personal theory. There are two main factors that affect accuracy. We will go with patched round balls, but the same principles should hold true for conical.

1. The number of revolutions per minute of a projectile are a key factor in how well it is stabilized for any given speed (I could be convinced that it's speed is not relevant). This number will change depending on the mass of the projectile. Smaller balls need higher RPM's to stabilize versus larger ones. Changing the amount of powder changes the velocity that the projectile leaves the barrel, which affects it's RPM's and its ability to be stabilized at any given speed. There may be more than one rate of RPM's that stabilize it, and there is likely a mathematical logic to it. It might be that the best stabilization happens at multiples of the same spin rate once a certain RPM is achieved. Or it might be 50% more RPM's. It is often reported that there is a lower and higher power load that achieve accuracy. If you took one 70 inch barrel and sawed into two barrels, one 30 inches and the other 40 inches, you could theoretically have two identical barrels with the exception of the length. If you were then to mount them into rifles and put the same load into them, you would not get the same muzzle velocity out of them. Which means that they would be spinning the ball at different RPM's and have different levels of stabilization. That doesn't mean that one is more accurate than the other, it just means that they will have different loads that are most accurate.

2. Your individual rifle combined with how you shoot it. Everything about how a rifle is constructed and how you shoot it has an effect on accuracy. The depth of the rifling, the patch and ball combo, the lube you use, whether you brace it against a tree or shoot it off hand, the barrel harmonics, the rate of twist, the depth of the rifling, etc. The exact same rifle may shoot differently for two people because one has a different stance and the pressure they put on the barrel changes how it flexes as the ball travels down the barrel. The rate of twist or depth of rifling may effect whether gasses blow by the patch and ball combo, which then effects it's muzzle velocity and natural stabilization. The rate of twist and barrel length can effect how the gun recoils in the hand. There are any number of factors that influence accuracy and each gun is somewhat unique.

 

[Pukatea Bay Boy]

So here are some examples of rifling old and new...,

Here is a hand cut barrel. Note how thin the grooves, and that there are an odd number of grooves because the land opposite the groove was needed to support the shaft holding the cutting bit...

View attachment 182482

Here is another antique. Again very thin rifling but an even number of grooves..., yet this is hand cut for sure....,
How did the barrel maker achieve this ???

View attachment 182483

The cutting machine used for the above barrel has grooves opposite while being a hand cutting machine, because (I'm told) the machine had two cutting bits, opposite of each other, thus they cut at the same time and supported each other while cutting. Saved manufacturing time too, reducing rifling time by almost half.

Here is another barrel done with a double cutter by hand...

View attachment 182484

Here is a modern cut barrel.... NOTE the grooves are now wider than the lands, a completer reversal of the situation in the originals

View attachment 182486

Now here is round bottom rifling. NOTE how although the grooves are not quite as wide as the lands, they are also rounded at the bottom. My personal rifle has rifling done this way, It's a lot easier to do, I'm told by a machinist, as it reduces wear on the cutting tool edge, and companies market this as easier to keep clean.

View attachment 182487


Here's a machine cut barrel with grooves very much wider, than the lands.....

View attachment 182489

Here's a machine cut barrel where the rifling is a bit closer in similarity to it's antique ancestors having grooves a bit thinner than the lands... but still wider than the antiques... these also look really "shallow" to me, and I don't know if this would be good for a round ball ....

View attachment 182488

LD

Morena from NZ .
My word that post ( a Wylie ago) was fascinating.
Tatou very much for your input.
I really learned a lot there.
Happy New year to you & all your whanau ( family)
Nga mihi
( kind regards)
Chris