Author Topic: .223 Twist Rate?  (Read 36895 times)

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ROGER4314

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Re: .223 Twist Rate?
« Reply #15 on: November 04, 2012, 05:08:18 PM »
Pete, that write up was factual and well written. Thanks for posting it. It's not often that someone actually points to the length of the projectile (and not the weight) to determine what barrel twist to use. That is essential information and not well understood.

I was at the range a few months ago and a guy down the row was cussing his rifle at high volume! He was super pissed and it was easy to hear his complaints. He changed to solid copper bullets in his .30 caliber rifle and the bullets were all over the paper. He kept screaming that his copper bullets were the same weight as his accurate jacketed lead bullets but the copper bullets wouldn't shoot worth a flip! Applying that situation to your description, copper is less dense than lead so the bullets had to be LONGER to get the same weight. The long copper bullets wouldn't stabilize in his rifle barrel even though the weight was unchanged.

Did I help him or set him straight? Heck, no! He was in no mood to get a lesson on barrel twist rates! If I see him at the range, again, I'll talk to him, then.

Flash
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tungsten74

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Re: .223 Twist Rate?
« Reply #16 on: November 16, 2012, 09:39:42 PM »
1x8 out of a 18 inch barrel would be good for the same 40-80 grain with good results? or should i be looking more to 62gr? something iv been looking for the information but haven't found really good results.
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Frisco Pete

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Re: .223 Twist Rate?
« Reply #17 on: December 16, 2012, 06:01:09 PM »
If the barrel and the bullets are good (bullets concentric) then I can foresee no problems.

Anymore we can shoot light bullets from fast twists better than in the past because the bullets are better made and more concentric.  When manufacturers tolerances weren't as tight, a slow twist helped these less-than-perfect bullets shoot better.  With great modern bullets like the light versions of the V-Max and Ballistic Tip you can get good results even in a fast 1-8" twist barrel.
Because of this manufacturers are now quickening the twist of some of their rifles to 1-9 etc when they once were 1-12" or 1-14".  Good modern bullets can take the rpm stress and not fly off out of the intended path.
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skid00dl

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Re: .223 Twist Rate?
« Reply #18 on: February 04, 2014, 10:54:17 AM »
Great writing, Frisco.

I shot some 77 gr Nosler match bthp's that I had loaded for Sweet Amy's tack driver with 1-7 twist, through my brother-in-laws M16A2. They keyholed at 25 yards.

ImTryin

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Re: .223 Twist Rate?
« Reply #19 on: June 08, 2017, 12:16:19 PM »
In in 9 or 1 in 8 seems to be the sweet spot for the average, go to the range, set up a target at 100 yards an plink awhile, shooter
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Rocketvapor

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Re: .223 Twist Rate?
« Reply #20 on: June 08, 2017, 12:21:45 PM »
Since the A-max's have been mentioned I'll toss in another thought about stability. 
The stability factor based on spin, mass, and length has to be modified for long bullets with a light weight nose. 
They are long which helps with drag, but appear shorter with respect to spin stability. 
Most formulas have been updated to compensate for this. 

Other than the fact that the 75gr A-Max is really long, it seems to do quite well in bolt and AR guns with twists 1:9 or faster.  That group of tumblers seems out of line with what I've read (interweb:).   I would expect the length or the lead/copper section to be comparable to just about any 75-77gr boat tail as far as spin stability goes.  Load length is an issue.  Mag length loading of the 75 A-Max would likely be difficult to control.  Maybe not getting it up to a reasonable velocity to stabilize it would be an issue with a shorter barrel since rpm is the parameter that matters. 

I don't have a 1:9 but the 75 and 80 A-max does pretty darn good from a 1:7, a 1:7.7, and a 1:8.
« Last Edit: June 08, 2017, 01:11:48 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

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https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Frisco Pete

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Re: .223 Twist Rate?
« Reply #21 on: December 12, 2017, 04:35:46 PM »
You also need to keep in mind that even if a barrel maker says its a “1 in 9 inch twist” that due to manufacturing tolerances that it can vary from that exact ratio to a degree. Therefore if it is say, a 1-9.3” twist in actuality, it may not stabilize long bullets at the velocity they are driven. Whereas another “1-9”” barrel might really be 1-8.8” twist and stabilize the same bullet. That is why 1-9” twist barrels are on the edge of what may or may not stabilize. Some really long bullets will stabilize in in a “1-9” barrel but not in the 1-9” of another rifle with a different barrel.

This reared its head with the original .244 Remington round (1955). It had a 1-12” twist in the Rem 722. The 6mm bore competition, Winchester’s .243, had a 1-10” twist. 100 grain .243/6mm bullets were available for reloading and the .244 often - but not always - wouldn’t stabilize them. But some .244 Model 722s would. Remington planned on just using 90 grain bullets for deer, but the popularity on deer of these new 6mm bore rounds was high and hunters felt better using a 100 grain bullet.

Eventually Remington changed the name to 6mm Rem and changed the twist to a 1-9” (a bit of overkill). This allowed the successful use of 100 grain bullets in every single 6mm rifle.
But there certainly was controversy as some of the .244s would stabilize the 100s. Probably due to the barrel and minor twist rate differences it was felt.
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Rocketvapor

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Re: .223 Twist Rate?
« Reply #22 on: December 12, 2017, 05:23:19 PM »
 
The 80 grain, 0.224 ELD-M, has the calculated stability factor (JBM Calculator) shown below;
Shown is the S.F. for 1:8, 1:7.7, and 1:7 twist @ 2700 and 3000fps.

          1:8    1:7.7     1:7
2700  1.44    1.56     1.88
3000  1.49    1.61     1.95

A non-tipped 80 gr of the same length would have the following stability factor;
(probably a little better if an OTM design)
2700  1.15    1.24    1.50 
3000  1.19    1.28    1.55

The S.F. of a 75gr A-Max from a 16", 1:9 (probably about 2700fps max) would be 1.14 and very under stabilized.
« Last Edit: December 12, 2017, 05:41:26 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

mogunner

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Re: .223 Twist Rate?
« Reply #23 on: December 12, 2017, 06:49:09 PM »
I put together a 1:8 twist 16" barrel AR and used a different barrel manufacturer than I usually do, and it doesn't seem to like the 55gr FMJ much at all, I'm thinking I may have to try heavier bullets and see how it does

Rocketvapor

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Re: .223 Twist Rate?
« Reply #24 on: December 12, 2017, 07:29:15 PM »
RPM and the little 55 grain bullet probably caused it to perform poorly.
Even though the 55gr is a pretty sturdy little bullet it will do better at 250,000 RPM or less.
Get up close to 300,000 RPM and it might become unstable.

The 80 ELD example I posted would be 270,000 RPM (3000, 1:8 ) or
over 300,000 (3000fps, 1:7). The thin jacket of the ELD just might do better with the 1:8 (or 1:7.7) at higher velocities. 
« Last Edit: December 12, 2017, 08:04:28 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

SweaT-Rex

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Re: .223 Twist Rate?
« Reply #25 on: December 12, 2017, 07:44:32 PM »
One of the nice things about reloading is finding the perfect "fit" for your particular rifle.  I don't own a AR, but my Arsenal SLR-106fr 5.56 NATO AK has a 1- 7" twist rate & happily shoots 55-77gr bullets.  However, it really likes a 65gr bullet.  Once you know that, you can start experimenting with OAL to find out how far off the lands it likes to be... within the limits of the magazine of course.  Then, you have to figure out which velocity it likes, & then you have to match your optic BDC to that velocity, & then you have to find the most consistent powder with the least temperature variability & extreme spread for that velocity.... & then when you figure all of that out, you wonder "can I do that with cast lead alloy bullets" (which an AK rifle can BTW) because like me, it's over gassed & can reliably cycle with faster burning powders at lower velocity :lol:   Then, as a reward for all of your efforts, you realize that you have OCD & want to repeat this process with every caliber you own, so then you think " maybe I need to simplify...I'll buy an SKS or several because they only come in one pattern & one caliber & usually without optics, & then I can relax & be happy....but NO!...  these discussions pop up here too :banghead:

Just kidding guys....I've really enjoyed this thread.  Excellent info.
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Frisco Pete

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Re: .223 Twist Rate?
« Reply #26 on: December 12, 2017, 07:47:01 PM »
Much depends on the concentricity of the bullet. If the bullet is concentric then it is less affected.
And yes, this is a function of how well they are made - or rather up to what standard they are made. Russian bullets, not so much. Military FMJ, so-so. Match and bullets like the Nosler Ballistics Tips etc. moreso. Solid base bullets like the Ballistic Tip resist deformation at high speeds and in the case of their 40-gr .224” can be driven in excess of 4,000 fps successfuly.

And the smoothness of the interior bore has an effect on keeping high speed high stress bullets together. As a former .17 Remington owner, I know that with 4100 fps velocity some bullets would shed their jackets and “blue streak”.

It ends up being more than a math equation in the real world in the long run as far as how they perform.
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Rocketvapor

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Re: .223 Twist Rate?
« Reply #27 on: December 12, 2017, 07:50:51 PM »
Jacket shedding might be speed related (slides off the back end :) ),
But RPM pretty much defines stability. 
There are examples of fast twist barrels shooting short fat light bullets really fast, but not the norm. 

400,000 RPM and most bullets don't go far :)


What was the twist of your 4100fps .17 ?
Actually the question should be what was the RPM you were shooting?
(between 250,000 and 300,000 ?)
The 0.086" radius of the  .17 bullet should hold up better than a 0.112" radius of a .224" at high RPM. 
« Last Edit: December 12, 2017, 08:03:14 PM by Rocketvapor »
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html

Frisco Pete

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Re: .223 Twist Rate?
« Reply #28 on: December 12, 2017, 11:11:15 PM »
The .17 Remington in the 700 BDL has a 1-9” twist 24” barrel.
And they are rather thin-jacketed varmint bullets. That makes a difference. The factory Remington PHPCL was actually a plated bullet but it worked very well. Some early batches of Hornady HPs had issues. Later bullets seem to do better, and Hornady now makes a nice V-Max in .177”. The situation is akin to shooting 40/45 grain .224” bullets intended for the Hornet from a .220 Swift. In the .22 CHeetah (.308/.243 necked to .22) Jim Carmichael reported that the best bullets at 4200+ fps were the solid base Ballistic Tips. The solid base seems to help reduce bullet stress when all that pressure slams them into the lands perhaps.

I don’t know if you have ever seen a solid base Nosler sectioned, but they are solid jacket material in the entire boattail as well as have thick sides at the base. This also makes them longer for weight. If a rifle likes heavier (which is to say longer) bullets but you want to shoot a slightly lesser weight, those may allow a drop in one bullet weight category, i.e. .30 180-gr to 165-gr. The length is the critical factor once again.

I’ve also found that where a certain max but safe powder charge may be fine with a standard bullet, switching to a solid base Ballistic Tip can often show pressure signs. At least in experiments with the .222 and .223. Probably one reason the usual caveat is to work up again when switching bullets.
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Rocketvapor

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Re: .223 Twist Rate?
« Reply #29 on: December 12, 2017, 11:56:23 PM »
Thanks Pete.
I've never shot the solid base bullets. 
I'll watch for a bargain :)

I'm focused on the .224 75/80 AMAX and ELD at the moment. 
The goal is to work up a load with a couple powders, CFE223 and IMR4350 that I have plenty of and a seating depth that will be 3000fps with the 80 gr (or a tiny bit faster) for 600yd playing around. 
Well I guess my new **** stirrin paddle don't work . I got a like . WTF 😈

Flo just received her EXPERT Mid range card from the NRA.

https://www.yahoo.com/news/famed-ex-uss-john-f-003916449.html