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how does the rate of twist affect accuracy in an AR.

I have a 20" barrel on a match target with a 1 in 7" twist. and I'm looking at a model1sales kit that has a 1 in 8" or a 1 in 9". which is the only 2 options they have on their barrels.

I only want to make a shorty and I know accuracy wont be that big a deal. but I was wondering what the differences were.

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how does the rate of twist affect accuracy in an AR.

I have a 20" barrel on a match target with a 1 in 7" twist. and I'm looking at a model1sales kit that has a 1 in 8" or a 1 in 9". which is the only 2 options they have on their barrels.

I only want to make a shorty and I know accuracy wont be that big a deal. but I was wondering what the differences were.

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the difference is for what weight bullet u use. if your going to use a very light bullet say 55 grains you want a faster twist to spin the bullet faster to stabilize it. if your using some of the very heavy weight bullets you want a slower twist. i may have them backwards and if so i am sure i will be corrected. the twist rates is the first number equals the twists in the lengts of the second number. so a 1 in 7 means one complete revolution for every 7 inches of barrel a one in nine means one twist for every nine inches of barrel. one in nine is a slower twist rate than one in seven

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I think he does have it backwards.

The 1 in 7 twist is a faster twist and is preferred for the heavier bullets to properly stabilize them

The lighter bullets tend to just spin themselves apart when spun too fast.

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Tighter twists are for the heavier bullets.

This is from the olympic arms website.. tech notes...

TWIST RATES

This is probably the single most important factor when purchasing a rifle or rifle barrel. The twist rate that will best suit you is determined by the weight of bullets that you will be shooting. The wrong twist rate for the particular bullet weight you are shooting can be disastrous to your accuracy. Many articles , and tons of information has been written about twist rates and what suits the bullets you plan to use best. We won't discuss that here. Your best bet is to call the bullet manufacturer for their recommendation.

We have 2 standard twist rates. One for the buttoned barrels (standard match), and one for the broached barrels (Ultramatch barrels). If your barrel is of the standard twist, no indication will be made on the barrel as to the twist rate. If the barrel has an alternate twist rate, that will be indicated by the appropriate stampings. In other words, anything other than the standard twist will be stamped on the barrel in the formula of  1 rotation of the bullet per number of barrel inches. Examples would be 1x7, or 1x12. These would indicate 1 bullet rotation in 7" of barrel, or one bullet rotation per 12" of barrel. The lower the number, the faster the twist. The higher the number the slower the twist. Generally speaking, a lighter bullet requires less rotation to stabilize itself than a heavier bullet.

http://www.olyarms.com/usa.html

the 1x7 twist rate is best for the 68-62 grain bullets..... 1x8 to 1x9 will do well for the 55 to 62 grainers. 62 grain surplus ammo is also sometimes refered to as "SS109" ammo.

55 grain surplus ammo is sometimes called "XM193"

If accuracy is not your major concern.. then dont be scared to shoot the 62 grain .223 ammo with a 1x8/1x9 barrel.... it may not be as accurate.. but it will still function fine.

Conversly... although the 55 grain stuff may not shoot as accurately in a 1x7 barrel.. it wont hurt anything either... ok>

If you were dialing in the rifle for extreme accuracy... then you'd need to worry about it more.

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So lets say I want general purpose accuracy, which twist rate should I get?

What ammo is cheaper and more common, 55 grain?

I heard I should just go with 1 in 9.

Thanks,

tom

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A good, general purpose twist rate for using most mid range weight .223 rounds would be 1x9. It'll do OK for the 62 grainers... and for the 55 grainers.

The 1x7 rate is best for some of the heavier bullets... 62 and up.

62 grain surplus is just as cheap for the most part as the 55 grain stuff. You can find them both is huge numbers for good prices at any gun show. ok>

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