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# Barrel twist rate

#1
09-21-2011, 06:49 AM
 Silver Member Join Date: Aug 2011 Location: Australia Posts: 102
Barrel twist rate

What's a barrel twist rate, my marlin XT22 is a 22WMR 1:16 barrel twist. What does a barrel twist do, maybe it's my ignorance but if you don't ask you don't no.
#2
09-21-2011, 09:23 AM
 Silver Member Join Date: Feb 2011 Location: alabama Posts: 125
Re: Barrel twist rate

Barrel twist is rifling inside the barrel that spins the bullet in a clockwise or counter clockwise direction when exiting the barrel. Rifling is described by its twist rate, which indicates the distance the bullet must travel to complete one full revolution, such as "1 turn in 10 inches" A 1 in 16 twist like you have in your rifle is considered a slow twist. A shorter distance indicates a "faster" twist, meaning that for a given velocity the projectile will be rotating at a higher spin rate. The combination of length, weight and shape of a projectile determines the twist rate needed to stabilize it – barrels intended for short, large-diameter projectiles like spherical lead balls require a very low twist rate, such as 1 turn in 48 inches (122 cm).[1] Barrels intended for long, small-diameter bullets, such as the ultra-low-drag, 80-grain 0.224 inch bullets (5.2 g, 5.56 mm), use twist rates of 1 turn in 8 inches (20 cm) or faster.[2]
#3
09-21-2011, 09:25 AM
 Platinum Member Join Date: Feb 2009 Location: Sedalia, MO Posts: 1,240
Re: Barrel twist rate

Aussie,

Twist rate is the distance in which it take the lands and grooves within the barrel to make one, full 360 degree rotation. This is important, in that this rate is what determines what bullets a barrel will, or will not, stabilze. The longer the twist, the lighter (shorter) the bullets will need to be to achieve proper stabilization. The longer and heavier a bullet becomes, the faster a twist it will need to remain nose on during flight.

Complex topic, but this is the gist of it. In the case of the 22 rimfires, there's very few twists available, since the 40 grain offering are pretty universal, and they don't get too much heavier or lighter than these. With centerfires, the bullets weight and lengths can go to some wild extremes, thus explaining why we commonly see everything from 1x6" to 1x16" twists in .22 caliber.

Hope that helps!
__________________
Kevin Thomas
Lapua USA

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