Barrel question - Lands & Grooves

B.Ruddick

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Some barrels have 6 lands & grooves and some have 4, what would be the reason behind this?
Does one serve better than the other?
For argument sake both barrels are 7mm and 1:10 Twist and 24" of equal contour.

My guess on the "4" is that the bullet has less surface area contacting the lands, which might generate less heat in the barrel, but that's just my guess, so maybe someone can shed some light on this for me.
 
I don't know of any particular benefit of the number of grooves...

Barrels have been made in 2, 3, 4, 6 and 8 groove... and 5 groove (as the post below stated)

The 4 groove are easier for the Benchrest Gunsmith to dial the bore in prior to boring the chamber.
 
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Seem to remember hearing of 16 groove rifling in some sort of target guns in the late 19th century. I think pretty well every possible thing has been tried and no real conclusions reached on this one.

Wasn't there even the odd enfield sent out with one groove during the height of war time production? Not sure how that would print! :)
 
Don't forget the Whitworth, hexagonal bored rifle.
That's right, no lands or grooves, a hexagonal bore.

Whitworthnobayonet1.jpg


[FONT=Verdana, Arial, Helvetica, sans-serif, Trebuchet MS]The Whitworth Rifle[/FONT]

[FONT=Verdana, Arial, Helvetica, sans-serif, Trebuchet MS]Sir Joseph Whitworth, one of the premier inventors and firearms designers of his era, manufactured his singular rifle in Manchester, England. It fired a unique, hard metal, hexagonal-sided bullet with a very long aspect ratio (.445 inches by 1.45 inches, or 2½ times its diameter) that gave it superior ballistic performance at extended ranges. In order to give his long bullet the same 530-grain weight as that of the Enfield, Sir Joseph reduced the caliber to .451. Seventy to eight-five grains of British-manufactured powder launched the bullet at twelve hundred to fourteen hundred feet per second, considerably faster than the Enfield. While the Whitworth's light weight meant that while a soldier could easily carry it around the battlefield, he could count on it giving him a heavy kick when he pulled the trigger. Overall, the Enfield made a better all-purpose infantry weapon, and equaled the Whitworth's accuracy to five hundred yards.
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[FONT=Verdana, Arial, Helvetica, sans-serif, Trebuchet MS]The rifle was available with and without bayonet attachments and came with a 36-inch or a 33-inch barrel, which made for an overall length of 49 to 52½ inches. All had a hexagonal bore and a fast 1:20 twist. "Typical 'Confederate Whitworths' featured a 33-inch barrel, two Enfield pattern barrel bands, iron mounts of the military target rifle pattern, and Enfield-type lock with no safety bolt and an Enfield-style hammer; open sights, with a blade front being adjustable for windage allowance, and a stock which extends to within a short distance of the muzzle, giving the rifle a snub-nosed appearance."
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[FONT=Verdana, Arial, Helvetica, sans-serif, Trebuchet MS]Sighting arrangements varied also. Some Whitworths had Enfield-type sights graduated to twelve hundred yards, and others had a sophisticated sliding blade sight with a vernier screw adjustment for windage; some had simple front sights, and others boasted an adjustable post-and-globe front sight. A few rifles sported a four-power telescopic sight, fitted in an adjustable mount on the gun's left side. While it was a state-of-the-art system in 1864 it did have its drawbacks. "After a fight those who used them had black eyes," remembered one sharpshooter, "as the end of the tube rested against the eye while taking aim, and the 'kick,' being pretty hard, bruised the eye."
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[FONT=Verdana, Arial, Helvetica, sans-serif, Trebuchet MS]Most of the men in the Army of Northern Virginia's sharpshooter battalions used Enfields, and only one or two men per battalion carried Whitworths. Thus in the approximately thirty-six infantry brigades of the Army of Northern Virginia, there were most likely between thirty-six and seventy-two of these rifles in service. Although some claims of its accuracy are no doubt exaggerated, the fact remains that the Whitworth could and did strike at a thousand yards and beyond. "The claim of 'fatal results at 1,500 yards,'" concluded one modern expert, "was no foolish boast." Overall, it was a deadly weapon that, in the right hands, repaid its high cost many times over. "I do not believe a harder-shooting, harder-kicking, longer-range gun was ever made than the Whitworth rifle," asserted sharpshooter veteran Isaac Shannon. (courtesy West Point Museum)[/FONT]
 
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H&K made some hex or octagon barrels much more recently.

The number of grooves varies a lot, depending on things like production time (war production) and the pet theories of the maker, as well as the equipment the maker has on hand to index to cutter holder.

In some cases, like modern cut rifled small bore barrels, the practical size of the cutter itself comes into play. The bore is small enough that a smaller cutter is too small to be reasonable durable in use.

Then comes the pet theories about the shapes of the lands and grooves, and the proportions in comparison to one another, etc. etc.

Most of the theories, IMO were crap, but the guys that believed them also did some first class work, which resulted in first class barrels.... When a craftsman believes what he is making is good, it usually works out that way. :)

Cheers
Trev
 
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