This is for the average gun enthusiasts and newbies that enjoy shooting and want a little more understanding of how a barrel twist rate can affect accuracy. So does barrel twist rate affect accuracy on an AR15? Posted on 02/24/2020 6:58:58 AM PST by w1n1
This is for the average gun enthusiasts and newbies that enjoy shooting and want a little more understanding of how a barrel twist rate can affect accuracy. So does barrel twist rate affect accuracy on an AR15?
The short technical answer is that barrel twist starts the bullet spinning at a given rate to stabilize the bullet. The rate has to be constant for the utmost accuracy.
On the opposite end of the spectrum – Decreasing the twist rate will almost certainly result in a dramatic decrease in accuracy. Another factor is can the wrong weight of the bullet for your twist rate make it fly off into the sunset? It does matter.
Bullet Weight Does Not Dictate Barrel Twist
The first thing that needs to be understood is that bullet weight does not directly have anything to do with what rifle twist you should be using – if its an AR15 barrel chambered in 5.56 NATO. Lets explain a little further.
The bullet length is what dictates your barrel rifling twist. A general rule of thumb with weight, is that the longer a bullet is, the heavier it becomes.
Newer types of bullets usually are lead-free designs, some are made of copper and zinc which is very light. So that requires the extra length to achieve the same weight compared to a lead core projectile. So with a longer bullet that you’re shooting, the faster the rifling twist needs to be to properly stabilize the bullet in flight. Its important to have great stability because it means great accuracy as well.
Barrel Twist
The technical definition is that the twist rate refers to the rate of spin in the rifle barrel, and is represented in inches per turn. It's important that your barrel has an adequate twist rate to stabilize the bullets you're shooting.
A barrel that is a 1:10" twist means that the rifling will spin the bullet one revolution in 10 inches. After the adoption of the M16A2, the military started using a 1:7 rifle twist, which was faster. The rifling made a complete revolution within 7" now instead of 14." We are talking twice as fast.
When it comes to slower rifle twist, i.e. 1:14, 1:12, 1:9, you really shouldn’t be shooting bullet weights over 65 grains or the equivalent length for a 65-grain bullet. It won't damage your rifle, but you will have very poor accuracy. Read the rest of rifle barrel twist rate.
Too high of a twist rate + too much velocity can cause the bullet to deform or even shatter after leaving the barrel due to centrifugal force. I would postulate if that does happen, it will significantly affect accuracy.
It will cause the rifle to just twist around and around in your hands.
I had never thought of that:)
If the rifle is on a sling it will snatch your head clean off.
Read it on the internet.
During the D.C. Sniper hubbub, Katie Couric did a sit-down with an ATF agent, on the TODAY Show. She was rolling a .223 round in her fingers, and said “ I understand these bullets are particularly deadly because they spin in flight. “
The twit really said that?
An 80 gr. Sierra HPBT Matchking requires a 1:8 twist rate. My groundhog gun is 1:8, barrel from Lilja.
That is a silly question. Of course it does! Or go ahead and try a 1 in 48 twist on a modern rifle and get back to me.
Of course it’s a silly question. It’s the AM Shooting Journal.
Not sure this is true. Many benchrest guys use gain twist barrels with success.
Oh yeah Katie, it’s those darn .223 rounds again....
Yup. You’d think she’d have the sense to pre-interview the ATF guy, or do a little research. Probably thought she was too smart for that.
Depends on the weight of the bullet. Heavier bullets need a faster twist to stabilize them.
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