I ordered some Hornady 22 caliber 75 grain A-Max bullets from a small local shop. They came in and the fellow asked me what twist. I told him my barrel was 1in8. He told me he had the right one's for me. I went in to pick them up, and right on the box it say's "Twist Rate 1-8". Right next to the boxes I bought he had additional boxes that said "Twist Rate 1in9". Both boxes were Hornady 22 caliber 75 grain BT A-Max. Has anyone ever heard of this?? Do they make the same bullet differently for different twist rates?? I have never heard of this. I did not check the model # for the 1in9's, but the number for the 1in8's is #22792. Is this something new?? Tom.
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There are formulas for selecting the best bullet length for different rates of twist based on caliber. I suspect in this case there is a difference in the ogive between the two bullets changing the surface area that contacts the rifling. I looked on Hornady's site and I couldn't find nothing about it. They do make 4 different stock numbers in the 75 gr. It will be interesting to see what the other posts are on this.
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Did he just order the 1 in 8 bullets and the 1 in 9 bullets at the same time? If so, then maybe they are different. See if they have a different profile. I'm sure he'd open the other box to take a look. Maybe the 1 in 8 bullets are boat tails??
I ordered some Hornady 22 caliber 75 grain A-Max bullets from a small local shop. They came in and the fellow asked me what twist. I told him my barrel was 1in8. He told me he had the right one's for me. I went in to pick them up, and right on the box it say's "Twist Rate 1-8". Right next to the boxes I bought he had additional boxes that said "Twist Rate 1in9". Both boxes were Hornady 22 caliber 75 grain BT A-Max. Has anyone ever heard of this?? Do they make the same bullet differently for different twist rates?? I have never heard of this. I did not check the model # for the 1in9's, but the number for the 1in8's is #22792. Is this something new?? Tom.
I have never heard of this. However, the length of the bullet definitely determines the twist rate required to keep them flying pont-forward! For example, a bullet with a boat-tail must spin faster than a flatbase one of otherwise identical shape & size-the boattail making the one longer than the other. I had a .222 Remington with a 1/14 twist that shot 55-grain flatbase bullets into 0.5 MOA, and 55-grain boatails into about 4"!
Comparethe lengths of the two different bullets. If they are exactly the same length, both will work well in whatever twist is needed for that length of bullet.
Use the Greenhill formula to calculate the needed twist:
150 divided by thebullet length IN CALIBERS equals the required twistrate IN CALIBERS.
Let's sayyour 75-grain bullets turn out to be are 4.5 calibers long (1.008"). 150/4.5= 33.33 So, you rate of twist needs to beone turn in 33.33 calibers. Your caliber is .224", so 33.33 X.224 = 1 turn in 7.46". In this example, the bullet MIGHT be stabilized by a 1/8" twist. but will definitely work OK in a 1/7" twist. It would be on the very ragged edge of instability in a 1/9" twist. MV does help somewhat in stabilizing bullets fired in too-slow a twist, but not very much! I'd rather have a bullet spinning too fast ("overstabilized") than too slow. Usually. a bullet that keyholes when it strikes the target is spinning too slowly.
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I checked the bullets, and the boxes. Everything is exactly the same except the twist recommendation. It has been my experience in the past that Hornady is more consistent with their base to ogive measurement, and Sierra is more consistent with their weight. The ogive measurements on these bullets are the same. I guess Hornady just changed their mind?? Tom.
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West by God Virginia.
We need to stop using these terms today, "Sniper Rifle", "Tactical", "Assault Weapon".
I checked the bullets, and the boxes. Everything is exactly the same except the twist recommendation. It has been my experience in the past that Hornady is more consistent with their base to ogive measurement, and Sierra is more consistent with their weight. The ogive measurements on these bullets are the same. I guess Hornady just changed their mind?? Tom.
OK, Tom. Now measure the length of your bullet, convert the inch measurement to calibers, then use the Greenhill formula to see what the required twist is for that length of bullet. Let us know what it turns out to be.
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I will do that when I can. I called Krieger when I ordered my new barrel. I told the fellow at Krieger what bullet I wanted to shoot. He said go with the 1in8. That was the main reason why I went with the 1in8, I just figured he wasan expert. I will try what you say and see how it comes out.
I tried to order a box of 600 of the Hornady 75 grain A-Max's, but it was $16 cheaper to order 6 boxes of 100. I had a hard time believeing that!! When the bullets came in the 100 box-that is when the dealer noticed the difference, and pointed it out to me. I just assumed that Hornady changed their mind?? Tom.
__________________
West by God Virginia.
We need to stop using these terms today, "Sniper Rifle", "Tactical", "Assault Weapon".
Hornady Bullets?? Never Seen This Before
