22-250 twist rate.....

Originally Posted By: Martyn4802Why? Because that is the twist that most 22-250 owners want, and have wanted for over 60 years that I'm aware of.
I've also been shooting 22-250's for 45 years, and all rifles have/had barrels with 1-14 twists. As mentioned, 55 grain bullets with that twist is a match made in Heaven.
Nothing stopping you from buying a 22-250 with a faster twist barrel if that's what YOU want. But, please don't condem those companies that build rifles with 1-14" twist 22-250's. I only want the 1-14 twist Varminters.

But why? Its not as though you can over stabilize a bullet.

I suppose you could argue that some of the lighter more fragile bullets may come apart when put through a fast twist barrel, but to be honest I don't think there are a whole lot of examples.

I still say a faster twist is better virtually every time. With a few exceptions the faster twist does everything the slower twist does, and more.

Why would someone want a slower twist, when the faster twist means a more versatile rifle? Unless they are addicted to shooting a specific light fragile bullet.
 
For 55gr bullets,
.223 is traveling at about 2900 fps in a 1:12 twist => 174,000RPM
22-250 is traveling at about 3400 fps in a 1:14 => 174,857 RPM at the muzzle.
The two rounds are traveling at different speeds and need different twists to reach the ideal RPM

The problem with to fast of a twist is that you can over stabilize a bullet. If you spin it to fast it will start to wobble just a little because of the tiniest imperfection in the bullet, like when you spin an egg on a counter top, and become a tiny bit less accurate. Not enough to matter on relatively large critters, at relatively close ranges, out of field positions, but for bench rest competitions and shooting prairie dogs at 500 yards, it could mean unacceptable results.
 
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dogmessiah you have it backwards, the faster you spin the bullet the more
stable it becomes. and to answer the previous post, yes it looses speed, but
not enough that any shooter can ever tell.
 
If you had a perfectly shaped bullet that would probably be true, but in reality no manufacturer can make a perfect bullet with the center of gravity being at the geometric center of the bullet. There is going to be some imperfection somewhere in the bullet on same small level. When the bullet is in the barrel it has some axis of rotation, which will be running lengthwise at the exact geometric center of the bullet. When the bullet leaves the barrel it will start to spin about its center of gravity, and if there is any imperfection in the bullet it will cause the bullet to wobble. When the bullet is run at a higher RPM, the wobble will be exaggerated. This will result in a decrease in accuracy. With how tight tolerances are for most bullet manufactures, over stabilization for your average guy won't be a problem.
Lets say you loose 1/16 of an MOA. On a coyote at 300 yards from a field position, none of us capable of making that shot will notice or care about 9/16 of an inch in impact. On a groundhog at 600 yards from a portable bench you might notice 1 1/8 of an inch for the impact. The reason manufacturers have a 1:14 twist is so that the guys shooting at groundhogs don't have accuracy problems because of overstabilization.
 
In reality, the fast twist barrels should stabalize the lighter bullets. The reality is, sometimes the fast twists don't shoot the light bullets accurately. I've noticed this more in the .22 calibers (.223, 22-250 etc.) than in the 30 calibers.
 
In my original post, I said it would be nice if I could shoot heavier bullets thru my Tika T3 22-250. The thought of launching a 69grSMK at ~3100FPS is tantaliZing, but unrealistic. I have shot high power service rifle matches, and seen how well a heavier .224cal bullet can perform at long ranges. I'm just a fan of shooting long range,and you can't do that with a 22 centerfire unless the bullet weights are higher. Right now I'm stuck in the middle of the Michigan depression, so I have no funds to work with.
 
dogmessiah, I understand what you are saying but in reality quality bullets
can be stabilized with S.G. values as high as 2 with no loss of accuracy.
 
Originally Posted By: dogmessiahIf you had a perfectly shaped bullet that would probably be true, but in reality no manufacturer can make a perfect bullet with the center of gravity being at the geometric center of the bullet. There is going to be some imperfection somewhere in the bullet on same small level. When the bullet is in the barrel it has some axis of rotation, which will be running lengthwise at the exact geometric center of the bullet. When the bullet leaves the barrel it will start to spin about its center of gravity, and if there is any imperfection in the bullet it will cause the bullet to wobble. When the bullet is run at a higher RPM, the wobble will be exaggerated. This will result in a decrease in accuracy. With how tight tolerances are for most bullet manufactures, over stabilization for your average guy won't be a problem.
Lets say you loose 1/16 of an MOA. On a coyote at 300 yards from a field position, none of us capable of making that shot will notice or care about 9/16 of an inch in impact. On a groundhog at 600 yards from a portable bench you might notice 1 1/8 of an inch for the impact. The reason manufacturers have a 1:14 twist is so that the guys shooting at groundhogs don't have accuracy problems because of overstabilization.

This question bothered me so much that I spend a large portion of my night looking for an answer. I even sat through a youtube physics lecture.

After still being unsure, I went through the physics department at the univeristy looking for a prof with an open door, and some time on his hands. I found one thankfully, and managed to get myself the answer.

In short, what actually occurs is the the opposite of what you wrote. While its true the bullet begins to spin around its center of gravity, the effect of increased rotation serves to keep the bullet from veering off course. While its a difficult subject, and as I found out counter intuitive at times, the short answer is, the faster somthing spins the more stable it is.

There are a number of links I can post, and perhaps a better explaination, I try to will do so when I'm at home.
 
Craig,
What you said is correct, but for a single bullet. That is where engineers, chemists, and biologists have problems with physics profs, they like to look at single things; single molecules, single atoms, single sub atomic particles, single moments in time, single events, they rarely like to consider things in the bulk. In this case he is looking at a single bullet and a single flight path. The shooter on the other hand desires repetition of that flight path.
That bullet will be less affected by turbulence in the air (more stable) the faster it is spinning regardless of how its center of gravity relates to its geometric center, so in that sense you are correct. However if the center of gravity and geometric center are not the same, the bullet will experience something the long range shooters call spin drift, where the bullet drifts in the direction of the bullets rotation. If the lot of bullets you are shooting all have the exact same relationship between the center of gravity and the geometric center, then there is no problem. If they don't have that same relationship between the two they will have different amounts of spin drift. However in the real world there are going to be slight differences in how far the center of gravity is offset from the geometric center in a lot of bullets, this means the bullet your gun is sighted in at will experience a different amount of spin drift then the bullet you are firing at a prairie dog. This spin drift is more exaggerated at higher RPM and that is where you run into the problem of to fast of a twist, the differences in spin drift are also more exaggerated. The bullet isn't "overstabilized" as we say, it is actually less affected by outside forces; it is just that the slight differences between bullets is more apparent.
 
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I watched a sniper show on the history channel the other day and they were talking about spin drift. It actually causes the bullets to rise and go to the right (in typical twist rifles)of the original path of the bullet. The spin drift was constant for a specific bullet and could be calculated...

Now for what i think dogmessiah is trying to say...He's speaking about bullets that may have slight irregularities. Its like a tire on your vehicle that is out of balance. If you drive 15 mph (slow spin rate) it will not be noticable but if you drive 60 mph (high spin rate) the balance is very noticable becuase of the wobble of the tire.
 
That is a good summery of what I meant. I never have been elegant with words. The other thing is what do you mean by slight irregularities, for 99% of shooters hornady bulk 55gr SP's don't have enough irregularities to affect the performance of us or our guns. For a benchrest guy on the other hand the irregularity would be huge for the bulk soft points, and is still noticeable with match grade bullets; that is why they go with the slowest twist that they can get by with on their guns
 
Originally Posted By: dogmessiahCraig,
What you said is correct, but for a single bullet. That is where engineers, chemists, and biologists have problems with physics profs, they like to look at single things; single molecules, single atoms, single sub atomic particles, single moments in time, single events, they rarely like to consider things in the bulk.
That bullet will be less affected by turbulence in the air (more stable) the faster it is spinning regardless of how its center of gravity relates to its geometric center, so in that sense you are correct. However if the center of gravity and geometric center are not the same, the bullet will experience something the long range shooters call spin drift, where the bullet drifts in the direction of the bullets rotation. If the lot of bullets you are shooting all have the exact same relationship between the center of gravity and the geometric center, then there is no problem. If they don't have that same relationship between the two they will have different amounts of spin drift. However in the real world there are going to be slight differences in how far the center of gravity is offset from the geometric center in a lot of bullets, this means the bullet your gun is sighted in at will experience a different amount of spin drift then the bullet you are firing at a prairie dog. This spin drift is more exaggerated at higher RPM and that is where you run into the problem of to fast of a twist, the differences in spin drift are also more exaggerated. The bullet isn't "overstabilized" as we say, it is actually less affected by outside forces; it is just that the slight differences between bullets is more apparent.

I understand where you are coming from and I believe that you are correct.

However, I would argue, that spin drift by its self is a very small correction, and that any errors would be even smaller.
Not only that, but I would say that since spin drift is correctable, or a constant change in the point of impact, that the actual error induced would be very small indeed.

Now is the error induced from spin drift, more then the error overcome from the increased stability of the faster spinning bullet? Frankly I don't know.

Though I strongly suggest that when we are talking about things like this, we are talking about errors that are much less then even the slightest breeze.
 
I agree with that. They were correcting for spin drift when shooting at 1000+ yds. I cant imagine that it would make a substantial difference in POI for a typical shot. Many factors can make a small differnce at long ranges.(wind, altitude, temp, etc.) I also wouldnt think that the flaws in individual bullets would be enough to cause a major problem for a hunting rifle.(i have been wrong before) Personally i have never really considered irregularities in bullets when looking at rifle groups but i do understand what he is saying. I guess it could come into play in select situations. Put a crooked arrow in a bow and see how it works out.


I'm not smart enough to be able to calculate where the happy medium between faster and slower twist rates would be but i know there is one. Too far in either direction would decrease performance. Sounds like to me maybe someone should make a 1/13 and get the best of both worlds
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