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Im really lost right now.

So i wanted to try out some 50 gr sierra blitz kings in my 22-250rem 1-14 twist, a buddy gave me some to try. my best group was .2" of 4 shots and my worst was .5" 4 shots out of 7 diffrent charges. Loaded with H380 and CCI BR2 and lapua brass. The .2" group was with 38.5grs and a average velocity of 3580 fps out of a 20 inch barrel. The other node was at 40-40.5 bit is to hot for my liking. Not to shabby. Heres where i am confused, this is a polyomer tipped boat tail BC of .248 and length of .77" and every stability calculator i used said it had a stability of .92 and expect keyholes and terrible groups, optimal twist of 1-11". These are by far the most acvurate bullet this gun has ever shot. Did i miss something?
 

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Nothing is written in stone. Sometimes you have to really play with the loads to get a really good one for your gun. And sometimes, what really works well for you, won't do so for anyone else. ALlloading data is an average of things and sometimes you just don't fit into the average.
 
Stability calculators are basically a reasonable guess, unless they have tested the actual bullet. Shape matters as much as size.

Stability will change down range, this shows up easier with sub sonic shooting, when you check for stability first at short range to keep from having a baffle strike they can print fine. As you lengthen the distance things change.

I have had perfect holes at 50 and 100 yards only to have something better described as a knife cut than bullet hole at 200.

Check accuracy and stability on different spots on the target, at greater distance. If you pile ten shots on top of each other it's impossible to see a keyhole.

You may not start to see an issue until out a few hundred yards in a keyhole, but chances are your group will start opening up exponentially if the bullets are unstable.
 
There is no reason they won't shoot out of a 14 twist barrel. When the 22-250 came out the bulk of them were 14 twist designed to shoot lighter bullets. It wasn't until guys wanted to shoot heavy for caliber bullets that the twist rate came down.
 
The tip is ~subtracted from bullet oal with the Courtney adjustment to the Miller formula. What's your altitude & shooting temp?

I had developed for this bullet in 14tw & 223rem, but I'm at sea level and stability was too marginal to shoot well. I went to a flat based 50gr bullet and groups tightened right up. The purpose of 14tw it seems is for tighter than normal grouping results, like a trick, but at the expense of bullet availability/practicality for it.
That's ok, but my next barrel will be 12tw anyway (as should be standard).
 
As others have said, theory is one thing, reality in your particular rifle is another. For a 22-250, that great! The caliber itself is NOT one that is used in competition or serious target shooting, but rather a good caliber for hunting. Be happy and go with what you have.

Alex
 
A 1:14 will shoot 50 grain bullets all day long , I have never seen one that didn't. I have a .220 Swift AI , 1:14 twist , it will shoot 40 grain Noslers, 50 grain Blitzkings, 55 grain Blitzkings, 52 grain Bergers, 55 grain Vmax's , 60 grain Hornady SP'S , 60 grain Nosler Partitions , all with RL17 powder, IT WON'T SHOOT 53 grain Vmax's and I know why. Buy a bunch of various 22 cal projectiles and prove to yourself what your barrel likes, its more fun than staring at computer calculators.
And in conclusion , standard factory twist rate for 22/250 is 1:14 :)

regards
Mike
 
It is indeed a 1-14" i checked 4 times. Im plum tickled just confused about the stability calculator. Temp was 60 degrees and elevation is 3200 feet.
 
It is indeed a 1-14" i checked 4 times. Im plum tickled just confused about the stability calculator. Temp was 60 degrees and elevation is 3200 feet.

What might really confuse you then, is if you change powders and you lose stability:oops::(.

Don't know if this will help or hurt, again subsonic because it shows up easier.

All three bullets shot in a 1/10 twist at 950 fps MV, all three nice and round at 50 yards.

Stability factor from JBM, listed best to worst at 200 yards.

Berger 230 hybrid 1.640" S/F 1.056
Berger 230 OTM 1.600" S/F 1.131
Sierra 240 SMK 1.590" S/F 1.206

By calculator the SMK should be the best. Holes on paper show it to be the worst.
The two Berger bullets will change places if I change powders.

It's always worth a try, but the real story probably won't show up until few hundred yards down range. Be sure to use a nice stiff target for best testing.
 
It is indeed a 1-14" i checked 4 times. Im plum tickled just confused about the stability calculator. Temp was 60 degrees and elevation is 3200 feet.
Stopp429-
I measured some .224 Sierra BlitzKing bullets I have on my shelf, Sierra #1450, of recent manufacture. Length was about 0.787 inches. Length of the plastic tip was 0.145 inches.

Assuming standard pressure at sea level of 29.92 mm Hg, your elevation should have about 89% of this value, or about 26.62 mm Hg.

Using the jbm ballistics calculator, with these values for inputs and a velocity of 3580 fps, the stability factor is 1.290, with 1.300 considered "stable".

It doesn't take much variation in any of the inputs to produce a stability factor of 1.300. For example, if twist is altered to 1:13.9 inches, that stability factor becomes 1.303 = stable. If atmospheric pressure is reduced to 26.40, stability is 1.301=stable.

So, with just a little on the favorable side of the usual variation that occurs in velocity, barrel manufacture, weather, etc., you could be getting bullet stability. Too, it is often the case that calculation showing "marginal" stability in fact produce fine field results.

However, you may find that taking your rifle and loads to sea level or shooting in colder temperatures might produce larger groups showing evidence of instabliity. There's a good article on twist rates and factors in stability in the April 2017 issue of Rifle Magazine. The article is available online in pdf format.

--Bob
 
Stabilization, Gyroscopic Stability, has to do with bullet rpm which is calculated by velocity and twist rate.

A bullet requires a certain rpm to achieve it's highest BC potential. That is not the same as the minimum needed for stabilization. Most bullets are advertised with a twist to achieve the highest BC.

In your 1/14 at 3580 fps the bullet is spinning about 184,000 rpm.
In a 1/11 about 234,000.

A 100 fps increase in velocity will add 5,000 rpm to 189,000.
A 1/13 twist will add 14,000 rpm. to 198,000

So if you wanted to hit the same RPM as the 1/11 twist barrel you, would need about 4550 fps.

A good read:
http://bulletin.accurateshooter.com...fficent-varies-with-twist-rate-stabilization/
 
Thank you. Now how much does velocity play into stability. Will say 100fps make a big difference?
Very little to none.
People assign too much credit to velocity and notions of 'RPMs'..

Declared stability requirements come down -not to turns per time(RPM), but displacement per turn (with that displacement being at a standard air density). A bullet maker for example may say you need no more than 12" of displacement per turn (12:1) under StdMetro conditions. This passes tests. Where your air density is not at a 'standard' then both BC and Sg are affected by that different relative displacement(regardless of RPM's).
I calculate your Sg at 1.290(marginal) for that altitude & temp. At ICAO seal level standard, I calculate Sg at 1.145, and at your altitude but 90deg I get 1.364.

That's at 3200'/60deg/3580fps, so lets look at just what velocity does(at the muzzle);
1.117 at 2500
1.290 at 3580
1.302 at 3680
1.359 at 4500
1.440 at 5000
Notice that even while RPMs are twice as high at 5000fps compared to 2500fps, Sg barely crept up, and the bullet never reaches fully stable at the muzzle. The only reason stability rose at all with velocity amounts to the same reason BC went up,, the drag curve.
But, stability & BC are not tied either.
The bullet being marginally stable as it is for you, would seemingly tumble before transonic velocities, again because of it's drag curve, but it won't in reality. This, because by the time it slows to this velocity, turns have not slowed nearly so much. So you end up with way less displacement per turns down at that range. In fact by 200yds, your velocity will have dropped from 3580fps to 2954fps, and your relative displacement has dropped to 12.3:1, and by then your 200yd Sg is up to 1.567 (fully stable), while G1BC dropped from .321 to .293.
See, stability at muzzle release is way different than down range. It's going up down range, even while RPMs are dropping.

Hope this helps with understandings.
 
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Melted the plastic tip off a bullet and it measures .630" without tip and .780" with tip. If i punch in the .630" into bergers calculator it shows im good to 0 degrees. That should be fine but somedays in the feild it gets -20. I will try to get out and shoit a group at 300 and see how it looks.
 
Speed can help you out, and a 22-250 can make speed.
He could reach ~3800fps with 6" more barrel,, and it would only raise his Sg to 1.316
Wouldn't shoot so well over here on the coastline, where his stability would drop way more, and so would his BC (due to low stability + higher air density).

I don't know why gun makers choose wrong twists.
But 12tw vastly broadens 22cal bullet potentials over 14tw, and with no downside to it.
 
I average with 40.5grs of h380 a whopping 3730 via magnetospeed but its to hot of a load to sit and shoot in the heat. So i aettled for the lower node. Its hard to tell with this rifle even just neck sizing gives slightly flattened primers with starting loads but when i reach max there really flat and sticky bolt. So i like to keep them mid range. And the 20" bbl doesnt help at all.
 

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