lets disccuss rate of twist
 

trying to figure this out
the claim is you need x amount of twist for x amount of velocity.
and you get away with less twist if you up the velocity.
How does that work, I am not going to do the exact math but hear me out.
If say a 1-12 with a 50 gr at 2700 produces 100,000 rpm and the bullet takes x amount of time to reach target producing 300 revolutions in that time.
Now we up the velocity to 3400 fps producing 160,000 rpm and x amount of time to get to target but it will still only spin 300 times from barrel to target, its not going to spin any faster because of velocity. well yes and no.
a 1/12 twist spins once for every foot no matter what velocity its pushed at. so 300 ft to target its spun 300 times whether it was 500 ft per second or 3000 fps
so how does velocity stabalise it more ? it just gets there quicker with the same number of spins

I don't believe I've ever heard twist related to velocity...I have heard it related to the length of the projectile and the diameter bore...

What blows my mind is how the early gunsmiths in what is now Germany figured this all out in the mid 1500s...By the early 1700s the rate of twist for round balls was pretty standard...

Yes, the bullet spins faster because RPM's is revolutions per minute which is a measurement of time, not distance.
The bullet is more stable because as the the RPM's increase the centrifugal force around the axis of the bullet increases. Think about a top spinning. The higher the RPM's the more stable the top becomes even though it isn't moving over distance any faster.

The bullet will still spin the same number of times over a given distance. That is always constant due to the barrel being constant. Excluding outside forces like air resistance which create friction on both the spin of teh bullet as well as the velocity of the bullet.


As velocity increases the RPM's increase. So, as velocity increases you will not need as high a barrel twist rate to stabilize the bullet. If a bullet needs 150,000 rpm's to be stable a barrel twist rate of 1in12 will accomplish that with 2500 fps. If the velocity is increased to 3000 fps you only need a twist rate of 1in14.4. The bullets rpm's will remain the same even though the bullet will spin less over distance.

I asked this same question concerning a .30-06 which people claim can shoot everything from 55gr bullets to 225 gr bullets.


Where is "Relentless" when you need him.............Larry !!!

so bigbulls, your saying that as velocity is increased centrifigul forces are greater.
Like a bicycle going 1 mph or 100 mph. the wheels still turn the same amount of rotations in 300 ft, but at 1 mph the bike wants to fall over but at 100 mph it would stay up without a rider .
I can buy that

I think you are looking at it from a velocity stand point where what you are actually talking about is the Greenhill Formula...

This states that for a given bore diameter and length of bullet there is an optimum twist rate to stabilize the bullet...It's pretty hard to spin a bullet too fast, kinda like it's hard to spin a top too fast...Too slow and it starts to wobble, too fast and it's fine...

Does bullet weight have anything to do with it ?


Can any rifle shoot a 55 gr bullet and 225 gr bullet well ?


Will either end of the spectrum tumble and keyhole a target ?

LoL Like ol Larry or not he does liven things up.

Yes, that is correct. Except that the axis of the bullet is at 90 degrees from the axis of the wheel.

No, bullet length is a factor but not bullet weight per given diameter.


That's akin to saying that an outbreak of food poisoning livens up the ER. :s11:

Didn't get it all, but thanks for that La$$y.


I won't tell anyone. Thanks again !

He's saying that it is far better to have more twist than you need than to have just enough. you can't have too much twist up unto the point that the bullet starts to come apart. It will allow you many more options in bullet weights, profiles, lengths, loading techniques and velocities when working up loads.

In 2 barrels of all things similar except say 4" of length, will the extra length enhance the stability as well? Or only increase velocity? Or make no difference? Or both?

Sharpening my pencil......

7mm-08, 160 Barnes TSX, 9.25

Funny....the guy is on here for 15 minutes, and people are posting as if there is no tomorrow to hear what he's got to say...

maybe someone should take notes.

No. A bullet only needs 1-2 inches of barrel length to stabilize. Anything after that is just velocity.

What extra barrel length does is lessen the rigidity of the barrel. All other things being equal (Ie: quality cut chambers, quality barrel, crown, stock, etc... etc...)the shorter barrel will be more rigid and should be the more accurate barrel.


It's pretty much automatic at this point.

whats up with manufactures not getting the correct twist rates on rifles
cz and rem and browning have a 1-16 twist rate for the hornet which we know is way to slow.
cz makes the 221 in a 1-12 = corect, the 222 in a 1-14 = ehh, and the hornet in 1-16= wrong all three of these need the 1-12 or faster even

No, A 22 hornet was designed for and is loaded with very light weight bullets with very short ogives which equates to very short bullets. A faster twist rate is not needed for these short bullets. A 1 in 16 twist is fast enough to stabilize up to 50-ish grain bullet at hornet velocities, which is heavier than it was ever designed to shoot.

As for the others. You have to keep in mind that you are talking about production guns made for Joe Average. The 221 and 222 are nothing but varmint rifles (despite their competition origins) from a production stand point. The twist rates that they use are plenty fast enough to stabilize and and all typical 22 caliber varmint weight bullets.



Obviously none of this would apply to reloading and custom barrels and chambers.

Bulls,

That's what I thought..................?!

I know there was more to learn in there, but that was the gist of it.


Thanks

many people will dissagree with you on this.
copied and past:


ed.



more copying and pasting

A more significant issue concerning the Hornet is the question of optimum rifling twist rate, which has definite impact on accuracy performance with different weight bullets and different barrel lengths. The SAAMI-spec standard twist rate for the .22 Hornet is 1:16 inches, which dates from Whelen?s original work. This works fine in rifle-length barrels with the Hornet?s standard 45-grain (or lighter) bullets but not so well with other popular .224-caliber bullets weighing 50 grains and up (especially the long-nosed ones).

It's too slow and doesn't stabilize the bullets. Accordingly, several modern .22 Hornet riflemakers adopted 1:14-inch twists (Kimber's Model 82 and Ruger?s current Model 77/22 are two examples). European rifles like the Sako Model 78 remain 1:16. (My somewhat idiosyncratic fellow ST staffer Layne Simpson has long threatened to have a custom .22 Hornet benchrest rifle built with a 1:10-inch twist just to prove that it?s really capable of superb accuracy with match-grade bullets.)

A faster twist is also preferred for hand-gun-length barrels, even with standard 45-grain and lighter bullets, due to the inherent velocity disadvantage and shorter engagement time. T/C Contender been bored at 10- and 14-inch pistol barrels have always been bored at 1:14 inches. The new MRI BFR single-action revolver is specced with a very fast 1:9-inch twist rate (the benefit shows in the shooting chart). By contrast, the Anschutz Exemplar remained with the European preference for the SAAMI-standard 1:16, which is also the twist rate or the German-made barrel on the new Taurus Model 22H.

That pretty much repeated what I stated in my post.

The 22 hornet was never designed to shoot heavy, long sleek bullets. People that are loading longer, heavier, and sleeker bullets are asking it to do something for which it was never designed. These people will obviously need to rebarrel with a faster twist barrel in order to shoot these bullets.

Bullet weight has absolutely nothing to do with determining the proper twist rate for a bullet. Bullet length is what matters. Look at a hornets bullet profile and look at the profile of a bullet designed for the .223 or 22-250.

Now, the hand gun dilemma I fully agree with due to the velocity loss in a 10" - 14" barrel vs. a rifle barrel.






You may be surprised to know that a .22 long rifle barrel twist rate is also 1 in 16".

I aint buying that, 222 push a 40 gr to 3500 fps with no problems in a 1-12
a hornet is only gonna get 3 k and 2900 out of a 40 and 45 gr.
My NEF hornet is a 1-9 twist and it shoots 50 gr 45 gr and 40 gr hanloads, and 45 gr factory loads with the same POI out of all of them. She'll put 50 rounds in a 2" circle at a 100 using any one of these ammo

thats why the hornet didnt do to well, the 1-16 was to slow for even 45 gr bullets
like the 6mm didnt do well with a 1-12
they do get it wrong sometimes you know.

Again, I am going to say this as plainly as I can. The 22 hornet was never designed to shoot long, sleek bullets. It was designed to shoot very light weight bullets with very short ogives which makes a very short bullet. The 1 in 16 twist is more than acceptable for the intended purpose of the cartridge when it was designed.


A short and fat 35 grain bullet designed for the hornet.



A long and sleek 40 grain bullet for the faster 22 centerfires but should still be plenty stable in the hornets 16 twist.


A long sleek 50 grain bullet that likely would not be stable in the hornet.

VERY well done !!!

Thank you Bulls !

big bulls the hornet was designed for 45 gr bullets and a 1-16 was not fast enough.

from wikipedia:


"Older guns generally have a slower twist rate of 1-16" (or one turn in every 16 inches (410 mm) of barrel length) for lighter bullets with a .223 caliber dimension. Newer guns feature a faster 1-14" twist for 40 to 45-grain (2.9 g) bullets in the more standard .224 caliber."

the hornet was never known for accuracy in the early days, the 1-16 was the problem
some guns shot the 45gr ok and some didnt

why do manufacturers still build this gun in a 1-16 ? its not 1930 anymore.


go to this link and punch in the numbers.
http://www.realguns.com/calculators/riflingtwist.html
40gr vmax is .676 long at 2980 = a 1-13.4 twist