GG, I cheated. I had remembered an article about hexagonal bullets and refound the article in the 3rd edition of Lyman's "Cast Bullet Handbook" . I would recommend this book to anyone who casts or loads lead buddits. It is the bible of lead buddits.
Anyway, here is the article.
Sir Joseph Whitworth
About this time in Britain, Joseph Whitworth had one of the most outstanding reputations ever acheived by an engineer. Whitworth is still remembered for his steel, and his screw threads: he was the first Britisher to measure precisely. Further, he seems to have had a flair for personal publicity. He received a commission in 1854 to make extreme detailed and lengthy experiments with small arms entirely at Government expense, although Whitworth refused personal compensation. He built a fully enclosed range, apparently on his own property in Birmingham, where shooting up to 400 yards could be done indoors. Whitworth invented a precise machine rest which greatly decreased the importance of the human element in experimental shooting. Initially, he tested Enfield rifles, as well as many others.
The individual Enfields were found to vary considerably, both in accuracy and in physical dimensions. Poorly made barrels shot poorly. even in the best Enfields, a fair percentage of bullets did not actually take the rifling in the way that they were supposed to, particularly when the barrels were dirty. Severe leading destroyed accuracy. The short, fat Enfield Minie bullet was not well designed for accurate flight at long range.
Other contemporary rifle were found to have at least as many disadvantages. Apparently, however, Whitworth did not fire the Jacob's rifle. Perhaps none was available at the time. After disposing of all rifles already made, Whitworht produced a number of rifled barrels of different types and fired them in his machine rest. He was particularly fond of polygonal bores, that is bores that were regular polygons in cross section. He seems to have experimented with polygonal bores of from five to ten sides, but finally chose the hexagon.
The hexagonal-bored rifle did not originate with Whitworth. Actually, a hexagonal bore had been proposed for use by a celebrated shot, Sergeant Major Moore of the Royal Artillery, in 1839. He is said to have made up a single rifle of this type himself. Whitworth, however, brought to the gunmaking industry both precision and a scientific approach. He carefully evaluated all his long and costly experiments. His findings improved all rifles, as well as methods of testing them.
Hexagonal-bore barrels were made up with widely varying twists, as fast as one turn in one inch, and as slow as one turn in sixty inches. The Whitworth rifles finally produced in quantitly were Cal. 45 with a twist of one turn in twenty inches. he bore measured .451 inches across the flats and had a diameter across the rounded corners of .490 inches. The rifles were designed for hexagonal bullets swaged to exact shape under hydralic pressure. The original hexagonal bullet weighed 530 grains, which was the same as the Enfield Cal .577 Pritchett bullet then in use. Comparative shooting of the Whitworth and the Enfield was undertaken; the results were in favor of the Whitworth which had a "Mean Radial Deviation" from the exact center of the target fired at, of only 3.86 inches at 300 yards, and 23.13 inches at 1,000 yards. Enfields, even though clean and carefully loaded, averaged 12.69 and 95.01 inches at the same ranges. Mordern shooting with these same weapons verifies approximately these figures.
It was found that cylindro-conoidal bullets slightly less than .450 inches in diameter, with hollow bases, shot well in Whitworth rifles. These weighed, according to surviving specimens, 480 grains, 500 grains and rarely 530 grains. Whitworth himself seems not to have liked cylindrical bullets, even though some of the rifles he produced were furnished with moulds to cast these. He preferred the positive fit of a hexagonal bullet. He formed his bullets of a hard alloy of lead and tin, since they required no deforming to fit the bores. These hard bullets gave greater penetration and less leading. Tallow or grease wads were loaded between the powder and the bullet to lubricate the bores, as well as cut down on the amount of fouling.
The Whitworth rifles were found to foul badly, however, under certain circumstances. Even though the hexagonal bores had no sharp groove corners for fouling to accumulate, ramming of bullets became difficult. Whitworht designed a scraper which was mounted on the end of the ramprod. It was possible to scour the bore after each shot and then lubricate it with a new wad. This worked well, but was slow. However, long range accuracy and not rapidity of fire, was most desired.
So there you have "The rest of the story"!
Dang, GG, I want my JAG!