Probably on that ragged edge. Both guns might have problems if you didn't live up high. That's why I run the calculator set at sea level. I live at 4900 feet.
Twist Rate and Bullet Stabilization Problems
- Thread starter HowieG
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Probably on that ragged edge. Both guns might have problems if you didn't live up high. That's why I run the calculator set at sea level. I live at 4900 feet.
Speed helps some.
My 14/Swift sure doesn't like M855 62gr bullets.
No, No...Not no way. Sideways at 25 yards.
BZZZzzzzzzzzzzz.....
(52gr HPBT MatchKing is 3/8" at 100 yards though)
Y'all might what to take advantage of https://bergerbullets.com/twist-rate-calculator/
No, No...Not no way. Sideways at 25 yards.
BZZZzzzzzzzzzzz.....
(52gr HPBT MatchKing is 3/8" at 100 yards though)
Y'all might what to take advantage of https://bergerbullets.com/twist-rate-calculator/
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The military had to go to 1:10 for those 62 gr bullets. Now they are at 1:7 from what I understand. Some of their match loads are the 77 MatchKing.
I LOVE that 52 MatchKing! Always have some around. Very explosive at 22-250 velocities though. Got to watch what you shoot with them.
I wouldn't be surprised if the 223 is cut slower than the book says.
Oh, had to go back and read your earlier post. You mean your 223. Have you measured it?
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Oh, disregard. I had to go back and read your previous about your 223. Have you measured it??
No. I sold it. I now have a Mossberg MVP in 1-9 twist. It's more to my liking.
.308 Norma
Member
We're right at a mile high around here, and both my wife's and my 22-250s do real well with the good ol' Hodgdon load of 38.0grs of H380 behind Hdy 52gr SPBTs. My wife's 22-250 is a Winchester 70, and I don't know the twist. My 22-250 is a Kimber with a 1 in 12 twist.
Did I ever find that out a few years ago! Thinking they would work for pests (ground squirrels, rabbits and starlings) in the garden, I bought a box of those Aguila SSS (SniperSubSonic) 22LRs for my Kimber bolt 22LR rifle. Normally, I can keep 6 or 7 Winchester "Super Speed" 40gr bullets in about an inch at 25 yards with that rifle, but those darned l-o-n-g, Aguila 60gr "subsonic" wouldn't even stay on a paper plate at 25 yards. And when they did hit it, they often went through it sideways.
I don't have any idea what the twist rate of my Kimber 22LR rifle is, but it's obviously too slow to stabilize long, Aguila 60gr bullets.
Ever wonder what stabilizes bullets out of the ultimate varmint rifle? The 16 inch Mark 7 rifles on the Iowa class battleships are rifled with a right hand twist of 1 in 25 inches. There are 96 grooves that are 0.150 inches deep. This stabilized shells weighing from 1900 lbs to 2700 lbs that are 64 inches long. Each shell spins a little over 27 turns before exiting the barrel. The armor piercing shells are 72 inches long and the HC/HE shells are 64 inches long.
What diameter are the shells? The larger the diameter, the slower the twist to stabilize.
16 inches.
A word of CAUTION about the Berger Stability calculator. It is NOT set up to take account of plastic tips ala Nosler BT or Hornady VMAX. Berger doesn't make tipped bullets so it is not something they care about. If you put in a bullet length including the plastic tip, be prepared for it to tell you that your bullet is UNSTABLE. Either subtract your tip length, or use the JBM calculator below, which has a place to insert the tip length.
JBM - Calculations - Stability (jbmballistics.com)
JBM - Calculations - Stability (jbmballistics.com)
JFrank
Member
I don't put a lot of stock in those calculators rather stay towards what I actually see on paper.
Demi-human
maybe likes firearms a little bit…
Not quite along the same lines, but when I bought a Radical Arms 450 Bushmaster upper, and used my marked carbon rod to primary clean it, I counted a faster 1 in 14 twist.
Usually a .452 barrel is one in sixteen, or slower as you get into faster than pistol cartridges or older rifles and types.
I wonder where Radical got the rifling button?
Not to any detriment though, as it makes an impressive varmint rifle. Spinning a 300 grain bullet slightly faster makes for a little bit better result, I think.
Some humans say a fourty five or fifty caliber hole all the way through is already big enough.
If I can make a seventy caliber hole without shooting a one ounce slug(oww.), then why not do it?
I wasn’t going to eat that chipmunk anyway...
Blue68f100
Member
If you find your not getting the stability you may need to push it faster if you can. Sierra told me a couple of years ago when I question whether the heavy (SGK) bullet would stabilize in my 260 Rem. They told me it would due to shape, designed for slow twist. As i was testing it got more accuracy as I went up in velocity. I ended up at max load, no pressure signs and slightly under spec velocity.
JFrank
Member
A full profile on paper would definitely be an indication of a problem.
J
Speed does help some. If you run a calculator and experiment with inputting different speeds, you find out right away that you need a big increase to change stability very much.
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The JBM calculator uses absolute barometric pressure instead of altitude in feet. A standard sea level day is 59 degrees F at 29.92 in/HG. If you are higher than that, subtract 1.006 in/HG PER 1000 feet of altitude higher up to 5000 feet. So, 5000 feet would be 24.89 in/HG.
Also, the JBM calculator uses some kind of math on the plastic tips. It doesn't just subtract them from the overall bullet length.
Also, the JBM calculator uses some kind of math on the plastic tips. It doesn't just subtract them from the overall bullet length.
Yep, they seem to be approximate. I do use the JBM calculator BEFORE I buy a new box of expensive bullets to experiment with though. I don't want to waste my money on a bullet that, most likely, won't work.
Berger states that they use the military standard for stability which is fully stable at an SG of 1.5 and over.
The JBM calculator uses a civilian standard for full stability at an SG of 1.3 and over.
So, the color codes you get when running these calculators may differ from each other on the same bullet.
The JBM calculator uses a civilian standard for full stability at an SG of 1.3 and over.
So, the color codes you get when running these calculators may differ from each other on the same bullet.
Here is a chart I made up comparing the Berger and JBM calculators using bullets that I would typically be shooting. <EDIT> I didn't note on this chart that the TWIST I inputted was 1 in 14. Sorry about that. Also, SMK = Sierra Match King, SBK = Sierra Blitz King, NBT = Nosler Ballistic Tip. We all know what VMAX means.
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