Rifle twist?
- Thread starter imsoipy
- Start date
The rifling does matter to an extent. 1:9 is the most common on the market today and the rifling can affect the range, but not as much as the ammo. With a typical AR you are only looking at a mid range rifle. It is possible to get long range shots with it, but it is generally mid range.
The twist rate determines the length and weight of the bullets that can be stabilized in the barrel for accurate shooting.
The first AR series rifles had a 1:12 to 1:14 twist, which would stabilize the original round--55 grain FMJBT.
The 1:9 twist will stabilize those bullets, and the 62 grain rounds, which extended the accurate effective range to around 600 yards.
The 1:7 twist will stabilize bullets up to the 77 grain match rounds, which are generally used for match shooting.
The only commercially available rifles I know that have the 1:7 twist are Colt rifles. I could be wrong, however.
The first AR series rifles had a 1:12 to 1:14 twist, which would stabilize the original round--55 grain FMJBT.
The 1:9 twist will stabilize those bullets, and the 62 grain rounds, which extended the accurate effective range to around 600 yards.
The 1:7 twist will stabilize bullets up to the 77 grain match rounds, which are generally used for match shooting.
The only commercially available rifles I know that have the 1:7 twist are Colt rifles. I could be wrong, however.
armalite makes a SPR Mod 1 LE rifle with a 1:7 twist, i got the midlength version, wish i had got the LE, it has a short gas piston system. and it was cheaper.
when you refer to match rifles, is that long range shooting? i was told that an AR could stretch out to 1100 yards, what kinda rig would you need for that, and what king of ammo would you be shooting?
when you refer to match rifles, is that long range shooting? i was told that an AR could stretch out to 1100 yards, what kinda rig would you need for that, and what king of ammo would you be shooting?
NAK3D N1NJA
Inactive
The Sig 556 rifle comes in a 1:7. Also, there is a new 1:7 version of the ACR being offered as well
IMSOIPY, think of throwing a football. If you don't inpart a good spin to the ball as you throw it then it will wobble. With bullets, the longer a bullet is in relation to its diameter, the faster it needs to spin to stabalize. Since the bullet diameter is fixed (.223 in your case) the only way to increase bullet weight is to make them longer. That is why a heavier bullet needs a faster rate of twist (for a given caliber).
Rifle Twist effect distance one can shoot by determining the weight (actually length) of the bullet the rifle will stabilize.
The 1:7 mentioned above will stabilize 80 - 90 grn bullets. Not only will these heavy bullets shoot well at 600 yards, they've beat the records set by the 308s at 600 & 1000 yards in service rifle competitions.
Some 1:9s have been said to shoot 77s but I haven't seen any. Service rifle shooters normally use 1:8s and 1:7s to shoot 77 & 80 Grn bullets and 1:7s for 80 - 90 grn bullets.
Also 1:7s will shoot lighter bullets such as the 55 grn M193 military round for the M16a1s and shoot them quite will.
The same can't be said for the slower twist 1:12s shooting the heavier bullets.
Look at the chart below showing the 1:12 vs 1:7s. If one is going to error, then error on the side of faster twist.
The 1:7 mentioned above will stabilize 80 - 90 grn bullets. Not only will these heavy bullets shoot well at 600 yards, they've beat the records set by the 308s at 600 & 1000 yards in service rifle competitions.
Some 1:9s have been said to shoot 77s but I haven't seen any. Service rifle shooters normally use 1:8s and 1:7s to shoot 77 & 80 Grn bullets and 1:7s for 80 - 90 grn bullets.
Also 1:7s will shoot lighter bullets such as the 55 grn M193 military round for the M16a1s and shoot them quite will.
The same can't be said for the slower twist 1:12s shooting the heavier bullets.
Look at the chart below showing the 1:12 vs 1:7s. If one is going to error, then error on the side of faster twist.
Sweet Shooter
New member
Not so fast—
I have no scientific evidence to back up the following, they are merely my observations and hunches.
I believe that the faster twist slows down the round be it 55gr or 69gr—for a given max pressure. The slower flight—especially with heavier/longer bullets—equates to a greater MRT and while the heavier bullets are effected less by wind, the deeper trajectory gives us more potential for ranging errors.
I also believe that in .223/5.56 a 1-12 twist shoots faster, flatter and I have not seen key-holing with 62gr bullets up to 400 yards as long as the bullet is moving out real fast (never exceed max loads etc...). I also believe a longer barrel will allow a slower twist rate.
Lastly I also believe that key-holing also occurs with too fast-a-spin as much as too-slow. It is possible to over-stabilize with faster twists. For example if shooting slightly uphill (above the tangent to the earths gravity), after the bullet has passed MRT for a given MPBR, the nose should start to point downwards tangentially. With a bullet spinning too-fast the nose stays up and the base gets pulled down and shows the beginnings of key-holing.
And one more hunch—the faster twist rifling is too aggressive (except perhaps 5R) and messes up the jacket more equating to poor accuracy.
I know that's a lot of hunches but my hunches generally serve me well.
I have no scientific evidence to back up the following, they are merely my observations and hunches.
I believe that the faster twist slows down the round be it 55gr or 69gr—for a given max pressure. The slower flight—especially with heavier/longer bullets—equates to a greater MRT and while the heavier bullets are effected less by wind, the deeper trajectory gives us more potential for ranging errors.
I also believe that in .223/5.56 a 1-12 twist shoots faster, flatter and I have not seen key-holing with 62gr bullets up to 400 yards as long as the bullet is moving out real fast (never exceed max loads etc...). I also believe a longer barrel will allow a slower twist rate.
Lastly I also believe that key-holing also occurs with too fast-a-spin as much as too-slow. It is possible to over-stabilize with faster twists. For example if shooting slightly uphill (above the tangent to the earths gravity), after the bullet has passed MRT for a given MPBR, the nose should start to point downwards tangentially. With a bullet spinning too-fast the nose stays up and the base gets pulled down and shows the beginnings of key-holing.
And one more hunch—the faster twist rifling is too aggressive (except perhaps 5R) and messes up the jacket more equating to poor accuracy.
I know that's a lot of hunches but my hunches generally serve me well.
Bamashooter
New member
I have shot 75gr. in my 1:9 twist ruger ranch without issue. I reload 65gr. and 69gr. and the ruger loves the heavier bullets. I have also done well with 60gr.