Twist rate

Gymbo

Gymbo

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Can someone explain how the twist rate affects or limits the ammo I can use.

I bought a Savage Axis .223 from a fellow CGN and read an article that said a twist rate of 9 limits you to lower grain ammo that can be used ,,is this correct .

Thanks
 
Gymbo said:
Can someone explain how the twist rate affects or limits the ammo I can use.

I bought a Savage Axis .223 from a fellow CGN and read an article that said a twist rate of 9 limits you to lower grain ammo that can be used ,,is this correct .

Thanks
Click to expand...

I just shot my Savage 1-9 twist today for the 1st time. "It" liked the 55 gr and 69 gr better than the 53 gr but the 53 gr was grouping well.
See my comments in the following thread.

Savage 10 FCP-K .223 1st Range day

I think you will be ok from probably 53 to 77 gr.
It depends on the velocity and length of projectile as much or more than just the twist to stabilize and be accurate.

also google Greenhill formula, I believe

Cheers

PS The rotational (gyroscopic spin )stabilizes the bullet, it will rotate faster at higher velocities and fast spin rates like 1-8/1-9 barrels.
However there is a max rotational RPM. Seems like for that twist it is 3800 fps+ and at whatever rotational spin is max for that projectile, caliber, and length it will plastisize and fail from the stresses.
 
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I would say 1 in 9 is a good compromise. it gives you the option of shooting 53 to 69 grain bullets with good accuracy a much better choice than say a 1 in 12 that limits you to only the lighter bullets my model 200 which is also a 1 in 9 so far loves 69 grain boattails.
 
blasted_saber said:
its not going to explode if thats what your worried about. Some ammo will just be more accurate then others.
Click to expand...

No.. I wanted to better understand the twist rate issue and get info from guys who are using this model and see what they recommend. You guys that have more experience are the experts and I'm looking to learn.
 
ok well its simple. The faster twist rates ie; the 1 in 9 or faster 1 in 7 etc do a better job of stabilizing the heavier bullets.The 1 in 10 ,1 in 12 slower twist rate only stabilize lighter bullets 55 grain 40 grain etc.When you shoot a 69 grain bullet in a 1 in 12 twist barrel, accuracy usually sucks, but the faster rates like 1 in 9 usually do a decent job on the lighter bullets and give better accuracy on the mid range heavier bullets.
thats it.
my stevens 200 is basicaly the exact rifle that you have with the same 1 in 9 twist it shoots factory 55 grain bullets ok...about a 1 inch group at 100 yards but it shoots the 69 grain sierra boattail handloads into a wee little hole at 100 yards.
Dan
 
The lower the number means the faster the bullet will spin. 1 in 9 means the bullet will turn one revolution in 9 inches of the barrel. This means a 9 twist is faster than say a 12 twist. Generally the heavier the bullet is the more a faster twist is required.
 
roseau river rat said:
ok well its simple. The faster twist rates ie; the 1 in 9 or faster 1 in 7 etc do a better job of stabilizing the heavier bullets.The 1 in 10 ,1 in 12 slower twist rate only stabilize lighter bullets 55 grain 40 grain etc.When you shoot a 69 grain bullet in a 1 in 12 twist barrel, accuracy usually sucks, but the faster rates like 1 in 9 usually do a decent job on the lighter bullets and give better accuracy on the mid range heavier bullets.
thats it.
my stevens 200 is basicaly the exact rifle that you have with the same 1 in 9 twist it shoots factory 55 grain bullets ok...about a 1 inch group at 100 yards but it shoots the 69 grain sierra boattail handloads into a wee little hole at 100 yards.
Dan
Click to expand...

To all ....Thank you
Roseau river rat and Bedrock thanks for the clarification I got what I needed and the gun should meet my needs just fine
 
What ammo is best for yotes

Gymbo said:
Can someone explain how the twist rate affects or limits the ammo I can use.

I bought a Savage Axis .223 from a fellow CGN and read an article that said a twist rate of 9 limits you to lower grain ammo that can be used ,,is this correct .

Thanks
Click to expand...

OK ..in light of what I know now . Is there an ammo type/grain that is best for coyotes with this rifle in mind
 
Google the greenhill twist rate formula. All will be made clear. Essentially, the shorter the bullet, the slower the twist required (e.g 1:12). The longer the bullet, the faster the twist (e.g. 1:9). Try spinning a top, then try spinning a pencil. One will require considerably more rpms to stabilize.
 
Keep in mind that now days there is more to bullet construction than just lead based.
Composite bullets, copper and such are generally longer for a given weight, and may shoot better, or worse for a given twist rate.
It gives you something more to experiment with.
 
The heavier bullets drift less in the wind, so can be more accurate. This is important starting at 300 yards.

I use 80gr Sierra match bullets back to 1000 yards. Velocity must be max to get enough RPM to stabilize that bullet.

For 100 to 300, the 68 & 69 will shoot the best groups.
 
Bullet weight only indirectly influences stability with any given twist, the length of the bullet is what matters. The longer the bearing surface of a bullet of any given weight and diameter, the shorter the bullet will be. Consider a full wadcutter bullet which is essentially a lead cylinder, and is as short as a bullet of any given diameter and weight can be. A tapered nose as in the case of a jacketed round nose will result in a bullet that's a bit longer, a boat-tail increases the length more, the combination of a boat-tail and a secant nose section with a short bearing surface length results in a very long bullet but not so long as a bullet of the same diameter, style and shape, but made from a mono-metal rather than a copper jacketed lead alloy. So does weight play a part in stability, yes it does, but bullet style is critical. Your .223 will probably shoot a 70 gr Speer semi spitzer very well, but unless the twist is quick it won't stabilize a 70 gr VLD.
 
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