Twist rate for a short barrel?

I am new to flintlocks but I have been gunsmithing modern firearms for 35 years. Some of my knowledge carries over to flintlock but a lot does not. I am concidering a flintlock project that is not normal and was hoping for some advice. The project is a short rifle, .54 caliber with about a 14" to 16" barrel shooting patched round balls. My question is what rifling twist would give the best accuracy out of that length barrel? When you get into barrels that short should you run a faster twist and how fast? Pistol barrels seam to be running 1 in 20" twist while rifles are running 1 in 48" or 1 in 60". I am just looking for the most logical starting point. Thank you for your help.

Hmmmm, is this going to be a 54 caliber M4?

I would go with a 1:48 for that length but that's just a SWAG.

longcruise said:

Hmmmm, is this going to be a 54 caliber M4?

I would go with a 1:48 for that length but that's just a SWAG.

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I promise I would never put an AR collapsible stock and Picatinny rail on a flintlock, but I might put a high capacity clip that holds over 30 bullets on it so it can shoot over 100 deer a second.

Of course an M4 carbine that is actually an inline muzzle loader would be funny.

I'm hoping some of the experts will weigh in on this, because I find it an interesting question.

I am definitely not an expert, but I would think that a lower powder charge might be required or you end up blowing unburned powder out the muzzle of that short barrel. Conventional wisdom maintains you need a relatively heavier powder charge with a slow twist, so it would seem logical that a somewhat faster twist would be indicated for a markedly shorter barrel, as the OP describes.

I think the "Cap & Ball" guy from Hungary did a video on shooting an original German "Boar Rifle" which had essentially a pistol-length barrel. So, there is some historical precedent for a rifle as the OP described.

EDIT: Here is a link to that video: "Shooting an 18th Century Flintlock"

Best regards,

Notchy Bob

I have two short barrel rifles. Both are 30". One has a 1:48 twist and one has a 1:60 twist. The faster twist is for either conical or round ball. The 1:60 is strictly for round ball.
You are aware about the legal length requirement for short barrel rifles.

I don't think the short barreled rifle length laws apply to a muzzleloading traditional style gun. At least, by the Fed's. There might be State or local laws where it does apply though.

As for a twist rate, I'm only guessing but, for a patched roundball, the rate of twist isn't real important. I think a 1:48 twist in this case would be fine.
Now, if elongated bullets are going to be shot thru it, then yes, the rate of twist becomes important because elongated bullets need to have a high rotational speed in order to stabilize. A 1:20 or 1:36 rate of twist would probably work better than the 1:48.

Notchy Bob, that video is what started all this. It showed up on my suggested videos on YouTube and I was hooked. The only other information I could find was the below picture of it. I showed it to a couple of customers of mine and now they want one.

My normal line of gunsmith work in on submachine guns, short barrel rifles and shotguns so I am well versed in the laws regarding short barrel rifles. As Zonie said as far as federal law goes traditional muzzleloaders are not regulated in any way by the National Firearms Ace. State laws and state hunting regulations will have to be checked before I could sell any.

I am thinking of starting with something like a Hawken with 1 in 48" twist just because they are easy to get. I will then see how it shoots from 16" on down to 12"barrel. I can try faster twist barrels if I feel the need to.

My shortest is a rifle with a 25" barrel. It shoots the same charges as my longer rifle in that caliber and both shoot only round ball. I also have a pistol and that may be a different story.

An AR collapsible butt, with picatinny rail on a flintlock! Sweet! I may just build one to piss of some folks. [sarcasm/off]

1780's tactical, should it be rifled 0 twist or a bit faster? Lets do a 14 inch barrel for chuckles.

A 1780's tactical? Should be a smoothbore.

When I build this thing I think I am going to make it a switch barrel. One rifled and one smoothbore.

BWE Firearms said:

Notchy Bob, that video is what started all this. It showed up on my suggested videos on YouTube and I was hooked. The only other information I could find was the below picture of it. I showed it to a couple of customers of mine and now they want one.

My normal line of gunsmith work in on submachine guns, short barrel rifles and shotguns so I am well versed in the laws regarding short barrel rifles. As Zonie said as far as federal law goes traditional muzzleloaders are not regulated in any way by the National Firearms Ace. State laws and state hunting regulations will have to be checked before I could sell any.

I am thinking of starting with something like a Hawken with 1 in 48" twist just because they are easy to get. I will then see how it shoots from 16" on down to 12"barrel. I can try faster twist barrels if I feel the need to.

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Yep, that's the rifle! I had only seen the video, however, and missed the still picture. The photographer did a great job making a terrific portrait of an unusual and interesting firearm and its accoutrements.

The fellow in the video said these were used for hunting wild boar from horseback. That must have been good sport!

We hope you'll keep us posted as this project moves forward.

Notchy Bob

BWE Firearms said:

I promise I would never put an AR collapsible stock and Picatinny rail on a flintlock, but I might put a high capacity clip that holds over 30 bullets on it so it can shoot over 100 deer a second.

Of course an M4 carbine that is actually an inline muzzle loader would be funny.

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Maybe with a matching sidearm?

Bob, I will keep everyone updated as I make progress. I need to first get a flintlock and learn how to shoot it. I am thinking of either a Lyman Deerstalker or a Lyman Great Plains Rifle to start this project with as a proof of concept. If that goes well then I will start building what I want the final project to look like and see if there is any interest. I already have a number of NFA guys wanting one and have gotten a few from here expressing interest. We shall see what happens.

Bob, I am in Central Florida, where in Florida are you?

Might ask Bob Hoyt. He should know. I know you're not having it done by him but he would probably help as a professional courtesy.

Well I bought a .54 Cal. Lyman Deer Stalker with a 1 in 48" twist. I bought this gun because people on the board said Lymans were decent guns and it was cheep. I really didn't want to spend $1500 on something and chop the barrel without knowing if it would shoot. The day after it was delivered it had 10" cut off the end of the barrel leaving me with a 14" barrel. I re positioned the sights did a quick crown on the barrel and got ready to hit the range. As I said before I have never shot a flintlock and have only shot a muzzleloader a couple of times. I had some troubles at first getting it to spark enough to ignite the pan as well as just getting a flash in the pan and no boom. The more I shot it the better it got. I think I am starting to figure out how it likes the pan filled. I don't know if it affects flintlocks but it was quite windy today.

I shot it at 50 yards with 80 grains of 2F powder, a .530" ball with a .018 precut and lubed patch. I used 3F powder in the pan and it seamed to fire the best with the pan about 3/4 full. Besides the three rounds that I pulled off the rest of the seven rounds is a 3 1/2" group. With more practice I can bring that down. I need to get the gun working better then I will take it out and shoot it at 100 yards. It does not seem that cutting the barrel down to 14" effected the accuracy at all.

Please share any thoughts or advice. Thank you.

IME, accuracy isn't a function of barrel length beyond longer barrels tend to aid aiming.

The barrel length does, however, contribute to complete combustion of the powder charge (aka: power) - with longer barrels exhibiting fuller combustion than short barrels.

The rate of rifling twist, OTOH, does contribute to accuracy in muzzleloaders, depending upon the type of projectile used.

In muzzleloaders:

Patched round balls (PRB's) tend to give their best accuracy with a relatively slow twist, like 1:60"
Conicals and saboted or paper-patched boolits tend to give their best accuracy with a relatively fast twist, like 1:28"

A 1:48" twist is regarded as a compromise for shooting either PRB's or conicals from the same gun/barrel

That turned out to be a slick little shooter! I really enjoy short guns, odd guns, non-typical stuff like this.

Cool project! Interested to see how longer range testing works out.

36.8 grains of black powder is all that barrel length will burn efficiently. Round ball seems to be the most accurate in a range of 300-400 revolutions per second. You hit 300 rps at a velocity of 1200 fps.
You might check your load with a chronograph.

I have a 21 inch barrel 1/24 twist 50 cal and have a rabbit load of 25g of 2f followed by 25g of Malto Meal shooting a .020 patch lubed with avacodo oil. And get a 3 shot group with holes touching at 25 yards.