Straight rifling

[Nordnecker]

A friend was looking at an original gun at the Kentucky Longrifle Association booth. The owner of the gun informed him that the gun had straight grooved rifling. I had not heard of this before. He claimed it made the ball shoot more accurately than a smooth bore but didn't effect patterns with shot. What are your thoughts on this?

[drago]

I believe strait rifling was tried to help reduce fouling but did little to increase accuracy before twists were discovered to increase accuracy. I don't see how it would harm shot patterns but there must be a reason it was'nt used more. Maybe not enough gain for the trouble?

[Hungry Horse]

I agree with Drago, on the fouling part, but must add, that is would make it easier to load a good tight patched ball as well.

                  Hungry Horse

[Artificer]

I think the reason straight grooves in a barrel to reduce fouling never panned out was both for the added expense and because it made the barrels more difficult to clean, with no significant advantage of faster reloading.  

For those who used the various types of shot (as in bird shot), they had time to swab the bore if necessary before reloading and a smooth barrel is easier to seal with wadding or cards.  

The people who needed to reload and shoot quickly were those in the military.  They solved the problem of fast reloading by using round balls so much smaller than bore  (such as nominally .69 caliber size balls in Brown Besses that ran from .75 to sometimes almost .80 caliber when actually precision measured)  and wrapped with paper to somewhat effectively seal the bore, that reloading was not slowed down by a smoothbore and it made it much easier for the troops to clean the barrels.   Besides, it was often rather rare that a smoothbore musket armed soldier had to fire a lot of shots before using the bayonet.  

I am not sure if twisted bronze/brass bore brushes, that come out in the late 19th century, may have made a difference in large scale use of cleaning  straight grooved bores.   Such brushes would have been frightfully expensive until after the Industrial Revolution and especially after the Interchangeable Parts System was perfected.  Not only that, but the way those brushes crush down in use, would have made the frightfully expensive brass bristle brushes ineffective after little use.

Bottom line, "smooth rifles" made in this county would have been straight grooved if it was seen as a definite advantage, especially as twisted rifling was being done so much by even small shops. 
Gus

[Nate McKenzie]

I thought this was interesting, so I ran for my bore light and checked out my original rifles.  4 out of 10 had straight rifling.  They are all percussion fullstock Pa. rifles from different areas from the 1830-1840 period.  Could this have been some sort of a fad in that era?

[Dphariss]

According to a friend who had a 50 caliber GM smooth rifle barrel straight cut the there was an improvement in accuracy.
I have seen straight rifled Rolling Block shotguns made in Europe. About 16 ga. Why it was straight rifled I could not say.

Dan

[smylee grouch]

I wonder if some of the British gunmakers didnt try straight rifling in their smoothbore large cal. African game guns to help with the fouling.

[John A. Stein]

The only original long rifle I have, most probably made in Emmitsburg, MD has a mildly swamped barrel and straight rifling. I also have an antique fowler with octagon to round barrel straight rifling and and a rear sight. John Stein

[Dphariss]

I wonder if some of the British gunmakers didnt try straight rifling in their smoothbore large cal. African game guns to help with the fouling.

It does not help with the fouling and actually may make the gun harder to clean. I consider it largely a waste of time other than for experimental purposes.
It has all the cost of a rifle but does not have the superior accuracy.

Dan

[Bill Paton]

Dillin writes that straight rifling was probably for better patched ball accuracy than a smooth bore would produce, and therefore done to make a combination gun. He also states that straight rifled barrels comprised about 15% of all American rifles (seems too high to me), and those he had examined were made before 1800 (many original percussion double rifles exist with one straight rifled barrel). He reports a shooting trial between smooth bore, straight rifle, and twist rifle at 100, 200, and 300 yards at a man sized target in which the straight rifle performed slightly better than the smooth rifle.

A modern maker of swivel rifles told me several years ago that he used straight rifled barrels to shoot shot better than a smooth bore, but they were touchy in that respect and needed very careful load workup to get the tightest pattern, which was better than a cylinder bore.

However, I have examined two flint swivel breeches (one early Reading and one jaeger) with one smooth barrel and one straight rifled barrel. Given the great accuracy advantage of spiral rifling, I think the makers of those two swivels intended them to be combination barrels for shot or more accurate ball shooting than a smooth bore would deliver. If they hadn't intended for shot use, they likely would have spiral rifled the rifle barrel for better accuracy.

Dan mentioned a friend who reported more accurate shooting with straight rifling than a smooth bore. I would like some of you shooters to do an experiment to compare straight and smooth rifle accuracy, working up the most accurate patched ball load possible. Maybe Dan's friend already has the data I am after and could report it to us.

My take is that straight rifled barrels were intended to shoot shot, and also a patched ball more accurately than a smooth bore could.
Maybe some data from you modern shooters could shed light on this issue. I am eager for the materials and methods, and the results to be reported.

I think the European 16 ga straight rifled rolling block Dan mentioned is like my fancy German double SXS pin fire with one spiral and one straight barrel, likely intended for shooting balls at red deer and boars in the woods, and hares and birds as well.

Bill Paton

[Artificer]

I would be very interested to read how a straight grooved barrel would shoot bird shot more accurately than a smooth barrel with components available in the 18th or early 19th century.  

Prior to 1769, "bird" shot was generally made ovoid or even heart shaped and known as "Rupert Shot."  after Prince Rupert.  I doubt Rupert shot would have been very accurate.  

"Rupert shot was the most common lead shot (10,726 pieces) from the Dog River site. The production of Rupert shot was first detailed in a 1665 publication entitled To make small shot of different sizes; Communicated by his Highness P. R. [Prince Rupert of England]. It was made by heating lead in a colander from which small drops fell as pellets into a container of water. Rupert shot at the Dog River site dates to the Rochon occupation of the French and early British colonial periods.


We also recovered 1,557 drop shot, 176 buckshot, and 36 musketballs. Drop shot was invented in 1769 by William Watts, who, as the story goes, inspired by a hailstorm experimented by dropping molten lead through a colander from a height of 200 feet into a tub of water. The effect was to produce perfectly round lead shot. Shortly after he patented his idea, drop shot was being mass-produced at "shot towers" and soon replaced Rupert shot. Buckshot and musket balls are made from molten lead poured into two-piece gang molds. Some of the Dog River examples are spent (or fired), and others have teeth marks indicating they had been chewed. Lead sprues (waste from making shot in molds), and lead spillage and scrap indicate the lead shot was produced at the Dog River plantation."

http://www.southalabama.edu/archaeology/dog-river-weaponry.html

More info from the old forum:

http://americanlongrifles.org/forum/index.php?topic=625.5;wap2

After 1769 or most likely a few years later in this country when drop shot became commonly imported here, then to achieve the best accuracy - we get into the problem of uniformity of loading components.  I'm sure the better shooters then as now tried to use the most uniform components after trial and error showed what each gun liked best.  However, the problem for some time was getting uniform components, especially in this country and prior to the 19th century.  

In the modern made straight grooved guns, I wonder how some people came to the conclusion that they were more accurate than smooth barrels with bird shot?  Were the guns fired first with the barrel smooth bored and then grooved and shot again to test accuracy?  That's the only way I know of to give true test on whether the straight grooves might allow better accuracy with "bird' shot, I would think?   EDITED to add:  I would also assume this to be the best way to test accuracy with a PRB, I.E. first with a smooth bore and then straight grooved and tested again? 

Gus

[Dphariss]

Dillin writes that straight rifling was probably for better patched ball accuracy than a smooth bore would produce, and therefore done to make a combination gun. He also states that straight rifled barrels comprised about 15% of all American rifles (seems too high to me), and those he had examined were made before 1800 (many original percussion double rifles exist with one straight rifled barrel). He reports a shooting trial between smooth bore, straight rifle, and twist rifle at 100, 200, and 300 yards at a man sized target in which the straight rifle performed slightly better than the smooth rifle.

A modern maker of swivel rifles told me several years ago that he used straight rifled barrels to shoot shot better than a smooth bore, but they were touchy in that respect and needed very careful load workup to get the tightest pattern, which was better than a cylinder bore.

However, I have examined two flint swivel breeches (one early Reading and one jaeger) with one smooth barrel and one straight rifled barrel. Given the great accuracy advantage of spiral rifling, I think the makers of those two swivels intended them to be combination barrels for shot or more accurate ball shooting than a smooth bore would deliver. If they hadn't intended for shot use, they likely would have spiral rifled the rifle barrel for better accuracy.

Dan mentioned a friend who reported more accurate shooting with straight rifling than a smooth bore. I would like some of you shooters to do an experiment to compare straight and smooth rifle accuracy, working up the most accurate patched ball load possible. Maybe Dan's friend already has the data I am after and could report it to us.

My take is that straight rifled barrels were intended to shoot shot, and also a patched ball more accurately than a smooth bore could.
Maybe some data from you modern shooters could shed light on this issue. I am eager for the materials and methods, and the results to be reported.

I think the European 16 ga straight rifled rolling block Dan mentioned is like my fancy German double SXS pin fire with one spiral and one straight barrel, likely intended for shooting balls at red deer and boars in the woods, and hares and birds as well.

Bill Paton

I suspect that my friend does have the data. Since he had the SB barrel straight cut just for that reason. But he don't come here anymore. If he were to post it someone who obviously shoots with their keyboard would take him to task over something.
His BS tolerance is even lower than mine so he decided this place was a waste of his time.

Dan

[hammer]

It was explained to me a while back that straight rifling reduces the variables associated with shooting ball in a smooth bore. 
  The twist rifling of a rifle ensures not just that the round ball picks up gyroscopic effect but also that the ball exits the bore with the exact same characteristics every time.  The ball will then pick up variations such as effect of imperfect manufacture, air movement and temperature changes but overall it will follow a predictable trajectory time after time.   Because the ball has to follow the rifling there will, however, be a limit on the maximum velocity before stripping.
  When the ball travels along a smooth bore it will, to some degree, rotate a little in one direction or another.  And in an unpredictable way.   Even with a tight patch or the thick wad of crumpled paper from a paper cartridge each ball will leave the bore with a small unpredictable variation or spin.  To this will be added the external variations leaving the smoothbore less accurate overall than a rifle beyond a certain range.  (Though that may not necessarily be a handicap.  I have a friend who shoots a Pedersoli Brown Bess and can put his shots into a group the size of the palm of his hand at 50 yards, offhand).   The smoothbore is, however easier to clean and maintain.   And the ball can be pushed out at an incredible speed with no problem from stripping.
  The straight rifling is a midpoint between the two.  Well, probably nearer to smooth than rifled.   Reduced variables while in the bore over a smoothbore providing a more predictable trajectory, no limit to the velocity but more difficult to clean and maintain than a smoothbore though not to the same degree as a rifle.   So some of the advantages of a smoothbore with some improvement to accuracy  within hunting ranges coupled with the ability to punch the balls out at top speed.
I've always though his theory sounded convincing.  Must have been something to it or those guys wouldn't have spent good money on them.

[Dphariss]

It was explained to me a while back that straight rifling reduces the variables associated with shooting ball in a smooth bore. 
  The twist rifling of a rifle ensures not just that the round ball picks up gyroscopic effect but also that the ball exits the bore with the exact same characteristics every time.  The ball will then pick up variations such as effect of imperfect manufacture, air movement and temperature changes but overall it will follow a predictable trajectory time after time.   Because the ball has to follow the rifling there will, however, be a limit on the maximum velocity before stripping.
  When the ball travels along a smooth bore it will, to some degree, rotate a little in one direction or another.  And in an unpredictable way.   Even with a tight patch or the thick wad of crumpled paper from a paper cartridge each ball will leave the bore with a small unpredictable variation or spin.  To this will be added the external variations leaving the smoothbore less accurate overall than a rifle beyond a certain range.  (Though that may not necessarily be a handicap.  I have a friend who shoots a Pedersoli Brown Bess and can put his shots into a group the size of the palm of his hand at 50 yards, offhand).   The smoothbore is, however easier to clean and maintain.   And the ball can be pushed out at an incredible speed with no problem from stripping.
  The straight rifling is a midpoint between the two.  Well, probably nearer to smooth than rifled.   Reduced variables while in the bore over a smoothbore providing a more predictable trajectory, no limit to the velocity but more difficult to clean and maintain than a smoothbore though not to the same degree as a rifle.   So some of the advantages of a smoothbore with some improvement to accuracy  within hunting ranges coupled with the ability to punch the balls out at top speed.
I've always though his theory sounded convincing.  Must have been something to it or those guys wouldn't have spent good money on them.

Unless the ball is large and the twist pretty fast there is no real limit to rifle velocity other than that inherent to the use of a low velocity propellant. In the Kentucky rifle calibers 32-54 a 48 to 70 inch twist will give all the velocity the powder can produce. Which in most calibers is going to be 2200 or a little more in some cases. This is assuming the patch material is up to the job. Some of it is not.
Larger balls 66-72 caliber may have more problems with twists under 60" or so but even then recoil will be a factor before it strips unless the ball is too loose, poor rifling form or bad patch material or the rifle is very heavy. Very shallow rifling is another factor and the shallow "grease groove bullet" used by TC in some 48" twist barrels is where the "stripping" problem occurred in modern times.
 
Dan

[Daryl]

I owned a SXS hammer gun made by Husqvarna in 1928. One barrel was 16 bore and choked, while the right barrel was 13 bore, straight rifled.  They were both chambered for the 16 bore shotshell case and although 16 bore wads were loose and a poor fit in the 'rifled' bore, it did shoot decent patterns at close range from the straight rifled bore.
There was a legality reason for the straight rifling.  In Sweden, it was common for the farmer to use his bird gun (most commonly a 16 bore) for shooting birds or bunnys with shot and moose with a round ball loaded in the other side - ready for anything- ball in one side, shot in the other.
The Swedish government passed a law that only a rifle could be used for the shooting of (elk) ie: moose.
The Swedish company, Husqvarna then made these SXS shotguns with a rifled barrel on one side and a shotgun barrel on the other. Some of them were made with rifle ctgs. (12.2x47R as well as 20 and 13 bore)  The 20 bore straight rifled bores were oversize as well as mine, due to the shot side using a thick paper case. The round ball was factory (& farmer) loaded with black powder in a brass case- easy to tell them apart. The brass case, being much thinner, had to use a larger ball to seal and hold inside, thus the larger size for the straight rifled side.

Thus, the guns with straight rifling were for those wanting the ABILITY to shot shot in both barrels, but also not break the law when shooting their moose.

[Dphariss]

Thank you Daryl. I saw the straight rifled rolling block at the BPCR Sil. Nats one year and the gun was an import from Sweden if I recall correctly, Scandinavia at any rate, so your explanation falls right into place.

Dan