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Old February 16, 2009, 10:09 PM   #1
awaveritt
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CZ 427 223, rate of twist question

Can someone give me a quick primer on the discussion of "rate of twist" with respect to the .223 Rem? Everything I've read indicates the 1:9 twist stabilzes a wider range of bullet weights than a 1:12. Which weight of bullets does 1:12 not stabilize well? As a practical matter what does it really mean?

I'm pondering the acquision of a new CZ 427 American in .223 but it has 1:12 rate of twist, as does Rugers and Remingtons (at least in their lightweight sporters, which is what I'm after). This fact seems to bother a lot of folks. Can someone help me muddle thru this?

I really like this rifle and the price seems right. Plus it has a really pretty piece of walunut on it.
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Old February 17, 2009, 04:58 AM   #2
j.chappell
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I believe you are looking at a CZ 527, but that’s beside the point.

Anyway, a 1 in 12" will generally handle up to 60-63 grain bullets and is usually at its best with 50-55 grain bullets; a 1 in 9" will generally handle up to a 69 grain bullet and will generally give best results with bullets 55 and above.

Most guys that complain about the 1 in 12" are serious long range shooters who want to stretch the 223 well beyond the 300 yard mark and need that tighter twist for the high BC bullets they need to be competitive in their competitions. Others are just Band Wagoners or Armchair Commandos that think they need to use 77's for their 100 yard plinking (cause all the big boys do), lol.

If you are not going to be doing much long range work and by that I mean shooting in access of 300 yards I wouldn’t let that 1 in 12" bother you a bit.


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Old February 17, 2009, 07:51 AM   #3
Magnum Wheel Man
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apples & oranges... errr... well sorta...

I do alot of Contender ( single shot ) shooting, & I've reciently made a couple of my own barrels... one being a 223 carbine barrel... I traded in my older ( original ) Contender barrel in 223, because it was a 1 in 12 twist barrel... my new one is a 1 in 8 twist barrel...

the old barrel shot excellent groups with anything 50 grains or lighter, but started suffering a bit with 55 grain bullets, & 68 grainers would keyhole even at 100 yards... I'm regularly shooting out to 300 yards, & wanting a little less wind drift of a heavier bullet over the 45 - 50 grainers... mine being a single shot allows me to load a longer cartridge if practical ( I've even deepened the throats on a couple of barrels allowing me to shoot cartridges longer than SAMMI spec ) pulling the longer / heavier bullet out of case increases case capacity, as well as reduces pressure ( provided the bullet is not forced into the rifling ), allowing me to gain a bit more velocity, & tune for accuracy...

in a nut shell, there are twist rate charts available ( sorry, I don't have a link handy ), that list bullet weight ranges, for each twist rate... the 223 - 224 bore seems to have one of the widest ranges of bullet weights, & thus has many different barrel twist rates... adding a bit more velocity, will help stabilize a marginal twist rate for a heavier bullet ( 22-250 is normally a 1 in 12 twist rate, & can better stabilize a 55 grain bullet, than a 1 in 12 twist 22 Hornet... to use the increased veloity as an example )... going with more twist rate than is needed to stabilize a bullet is hard on cast bullets, & bullets of poor construction... my expirience with modern jacketed bullets, is there is no problem with the faster twist rates as far as bullet integrity... however, the faster twist rates can also raise pressues, by increasing the resistance for the bullet to leave the barrel... so if you are shooting max hot loads in a 1 in 12 twist barrel, you may have excessive pressures in a faster twist barrel...

there seems to be a couple schools of thought with the 223, the "velocity junkies" which want to squeeze out all the speed they can from a cartridge, for these guys, the lighter bullets & slower twist rates rule... then the "high balistic co-efficient guys" the heavy bullet guys, that want to shoot as heavy a bullet ( often the highest balistic co-efficient bullet...the most slippery ) bullet possible...these longer heavier bullets look lots more "wicked" standing still anyways, but generaly buck the wind better, & work better for longer ranges... hope this helps some...
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Old February 17, 2009, 11:08 AM   #4
j.chappell
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Quote:
my expirience with modern jacketed bullets, is there is no problem with the faster twist rates as far as bullet integrity...
That is mostly true but most manufacturers offer .223 and .224 bullets in highly frangible bullets for the slower 22 centerfires. Firing these bullets in excess of their recommended velocity in any twist, let alone a faster than recommended twist, can and will result in jacket separation upon firing.

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Old February 17, 2009, 11:30 AM   #5
Magnum Wheel Man
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J... again... only "my expirience"... but the "varment grenade" type bullets always seemed more sensitive to velocities, & less so of twist rates ??? but then I never played much with the "really explosive" bullet types
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Old February 17, 2009, 11:36 AM   #6
j.chappell
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J... again... only "my expirience"... but the "varment grenade" type bullets always seemed more sensitive to velocities, & less so of twist rates ??? but then I never played much with the "really explosive" bullet types
I wasn’t saying that you were wrong only pointing out that bullets like Sierra’s Blitzkings and Hornady’s SX line are designed to be shot under a particular velocity and pushing them to near max in a fast twist barrel can cause separation. The Barnes Varmint Grenades are designed to be shot at full power.

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