Barrel twist rates

[cidirkona]

After researching a few rifle I'd like to pick up, I see the same priced items that have the same barrel length and caliber -- just different twist rates. One is in 1x9" and the other 1x16", otherwise identical.

What is the difference between the two practically? Will the one with a faster turn rate give more perceived recoil? I'm used to just buying surplus rifles as they are and shooting 'em.

-Colin

(And yes, I've ran some searches here, but didn't find anything applicable).

 

[rbernie]

http://www.stevespages.com/page8e.htm

 

[cidirkona]

Wow, great page, thanks!

(Although, if my grandpa passed away and gave me 1 million bullets, there's obviously something he didn't tell me...)

-Colin

 

[Jim Watson]

What caliber?

You have to be careful with anything coming out of the Greenhill formula. It is empirical for the bullets and velocities of the day, and fudging the constant does not make it fit all situations. It is a VERY general guideline.

 

[Quintin Likely]

Typically, the heavier and (especially) longer a bullet is, the faster twist rate it will need to stabilize in flight. A twist rate in either 1:9 or 1:16 seems kinda oddball to me...what caliber is it? 1:16 twist sounds like a varmint rifle, something in a .22 caliber, like .220 Swift or .22-250, intended for throwing 30-40 something grain bullets.

 

[cidirkona]

.223 Oly Arms 16" AR.

God bless America -- it's only hard to buy a new firearm because there are TOO MANY to choose from!

-Colin

 

[Steve Smith]

Don't get the 1:16". Wow, what a waste that would be. Get the 1:9 and then you can shoot up to 75gr bullets.

 

[Ivy Mike]

Which rifle would need a 1:16 twist rate?

Isn't that what the .40S&W uses?

 

[Gunnutz13]

My 2 cents...

Hey Cidirkona....I have an Olympic Arms CAR97M4 chambered in 5.56 with a 1:9 twist 16" stainless steel barrel. Most Oly Arms platforms are configured with the same twist rate ( 1:9 ) and chamber specs ( 5.56nato ). You can fire .223rem in a 5.56nato chamber, but 5.56 in a tighter .223 chamber is not recommended due to SAMMI tolerances. The 1:9 twist stabilizes more different bullet weights than any other twist rate. More on this can be found at the site below...


http://www.ammo-oracle.com/

 

[Jim Watson]

I have never heard of a 16" twist .223. That is .22 long rifle twist, and some of the early Hornets 70 years ago. Do you think there might be a misprint or confusion with the 16" barrel length?

Any road, a 9" twist .223 is versatile. It will likely shoot 55 grain bullets ok, 62 grain SS109 well, and 69 grain match VERY well. It just won't handle 77-80 grain match bullets or SS110 tracers.

 

[cidirkona]

http://atlanticfirearms.com/rifles/ar15/ar15.html

Wow, ok, the 1 in 16" is a 22lr -- are the bullet lengths really that different?

-Colin

 

[rbernie]

Wow, ok, the 1 in 16" is a 22lr -- are the bullet lengths really that different?

In this case, it's more than a length issue.

The 22LR shoots a very soft 40gr bullet that isn't expected to NEED to be stable much past 100 yards (due to its low velocity). That means that a 22lr works best with a more gentle spin than, say, a 223Win that shoots a much harder 40gr bullet (can be spun up faster/more aggressively) and is expected to be stabilized for at LEAST 300 yards.

 

[Mike Hull]

My neighbor sold me a really clean 788 Remington, in .222 a couple of years ago. I was going to rechamber it for .223, but at the last minute checked the twist rate, and found it was 1-14". Only good for 40-50 grainers.

I ended up having it rebarrelled with a 1-9" .223.

 

[kaferhaus]

, but at the last minute checked the twist rate, and found it was 1-14". Only good for 40-50 grainers

Mine stabilizes 55gr bullets just fine... still got that old barrel?

 

[kaferhaus]

The weight of a bullet has no practical impact on the twist rate required to stabilize it. The length. and velocity do.

A high velocity 22CF like a 22-250 or 220 swift will stabilize a hpbt bullet weighing up to 63grs at full throttle. My 22-250 will stabilize a 64gr flat base on out to 300yds. however anything pointy boat tail over 63gr is a guaranteed keyholer at 100m.

I have a 223 with a 1:12 that wont' stabilize anything over 55grs

 

[Jim Watson]

Strange, my 788 .223 with 1-12" shoots 60 grain flatbase best of all. My 1-9" ARS Mini shoots the 50 grain Berger flatbase better.

My Long Range shooting friend was surprised to find his 1-9" Hart would shoot the very long 75 grain Hornady A-max bullets accurately. He thought that gun was obsolete because it wouldn't handle 80 grain Sierras, a 7.5-8" twist bullet, but now he has something to go with.

You can figger all the formulae and listen to all the war stories you want to, but for any combination of bullet and barrel that is not grossly mismatched, you just have to do the shooting.
Tough work, but somebody has to do it.

 

[Mike Hull]

Mine stabilizes 55gr bullets just fine... still got that old barrel?

No, I sold it to a local shop.

I wanted to shoot 69-75 grainers, hence the 1-9". I would have gotten 1-8, or maybe even 1-7, giving me the option of even heavier bullets, but they didn't offer those twists, and I didn't feel like sending it somewhere else, and not only paying way more, but waiting several more months.

I'm pretty happy with this barrel(Shaw).