Yet it seems the American flintlock rifle was seldom found with a shorter barrel. As shown by plmeek, apparently the long barrels were still popular in the fur trade, even in the larger 54 caliber.
People have rationalized that many changes in the American longrifle occurred for practical reasons, when in reality, fashion probably had a lot to do with it. The changing preference in barrel length may be an example.
Early gun writers speculated that the American longrifle evolved from the short barrel (30" or less) German Jaeger rifle, and that the longer barrel American rifle was necessary because of the poor quality of powder in the Colonies that needed a longer barrel to completely burn.
More recent research has shown that long barrel rifles were not uncommon in the Germanic countries of the old world in the first half of the 18th century and that long barrel Germanic rifles and long German rifle barrels were being imported into the Colonies in the 1730's (Lienemann, pg 66). Caspar Wistar, an emigrant from Germany that settled in Philadelphia, was importing rifles from Germany as early as 1737 with barrels "none under 3 feet and 2 inches long or preferably longer."
The theory that the Jaeger evolved into the longrifle envisions "transition" rifles of intermediate length barrels. The famous Edward Marshall rifle has been described by many as a perfect example of one of these "transition" rifles with its 37-13/16 inch barrel. The problem is that the barrel on the Edward Marshall rifle was most likely made in Germany and imported into the Colonies, or possibly, the Edward Marshall rifle is a restocking of a German made rifle of the type that Caspar Wistar was importing. In either case, it challenges the notion that the long barrel rifle was an American "invention".
Edward Marshall Rifle - 37-13/16" barrel
German Trade Rifle - 39-7/8" barrel
The customers in America simply developed a preference long barrel rifles, but they had previously existed in Europe.
Why the preference for longer barrels in the Colonies? The idea that the longer barrels were needed to facilitate the complete burning of the poorer quality powder available in the Colonies is not supported by evidence. In the Colonial period, very little gun powder was being made in the Colonies. Nearly all of it was imported. The same powder available in England and Europe was available in the Colonies. Surviving documents show that different grades of powder were available depending on source and price.
Modern experiments show that black powder burns extremely fast. The rate of burn is more a function of the size of the powder grains than anything else. Nearly all the powder is consumed by the time a ball travels a foot or so down the barrel. Longer barrels produce higher velocities because they provide more time for the expanding gases to accelerate the ball.
The quality of black powder is primarily determined by the purity of the saltpeter or potassium nitrate used to make it. British gunpowder improved in the middle of the 18th century when the East India Company gained control of Bengal and its supply of higher quality saltpeter.
Other factors that influence the ballistic quality of gunpowder is the size of the initial grind and mixing of ingredients (potassium nitrate, sulfur, and charcoal), the ratio of the ingredients, the type of wood used to make the charcoal, and the corning process (the process by which meal powder, or finely divided black powder, is compressed into cakes, crushed, and then screened by particle size).
Both long barreled and short barreled guns existed in Europe and England throughout the 18th century. As a general rule in the sporting world, a gun used to shoot waterfowl had a longer barrel than a gun used to shoot upland game. This distinction had little to do with powder quality and more to do with the distance the shot was expected to travel, the desired pattern for the shot, and the style of shooting.
The change in preference from a long barrel rifle to a short barrel rifle as described by Zonie and driven by the caliber size and power and the opportunity to be carried on a horse sounds logical, but it is more complicated than that.
The longhunters that ventured west of the Appalachian Mountains before and after the AWI to hunt deer and bear for their skins or to trade with the Indians for skins used horses to carry their supplies and trade goods out and the skins back. Out West, there were several trading and trapping expeditions from St. Louis to the mountains that used horses before 1822, and of course, many more after that date. Nearly all of these trappers and traders that carried a rifle had a long barrel Kentucky rifle. The short barrel "plains" rifle didn't become popular until after the end of the mountain man era.
Many of the surviving J&S Hawken rifles have barrel lengths in the range of 37" to 39" and some are as long as 42". The typical St. Louis "plains" rifle with barrels 30" to 34" long by likes of S. Hawken, H. E. Dimick, and J. P. Gemmer didn't come about until 1850 and later. The same with the short barreled Leman Indian rifle.
Late 1833, the American Fur Company ordered 20 steel mounted rifles with 38" barrels from J.J. Henry. I suspect the steel mounted Henry rifles, which were first ordered at the end of 1830 in 42" and 44" barrel lengths, were in response to the gaining popularity of J&S Hawken rifles in the mountains. As stated above, barrels in the 38" range are common on surviving J&S Hawken rifles. In 1840, the AFC ordered J. Henry to make one Lancaster pattern rifle with a 30" barrel. This was the shortest barrel ordered since the 38" in 1833. Since only one was ordered, it appears to be a special order for an individual or a pattern rifle to test the market.
So if the short barrel "plains" rifle evolved because of the ease of use on a horse, it sure took a long time for the longhunter, mountain man, western traveler, and Plains Indian to realize it. At the sametime that the St. Louis gunmakers were cranking out their "plains" rifles, the short barrel, half stock rifle was gaining widespread popularity in the Northeast, South, and all the way to California. for target shooting and hunting--most of it without the use of a horse.
As one looks into the details of when and where short barrel rifles were common, it sure seems like the preferences were driven by fashion more than practicality.
