Question regarding Bullet speed vs twist rate stability

[voldoc02]

I have a 14 twist 22 BR Barrel and shooting 52 grainers at about 3750 fps.
I'm thinking of having this Barrel rechambered to 22 Dasher, which should
be pushing 4,000 fps. Question is , will this added speed make the 14 twist
less likely to stabilize the same 52 gr Bullets.
thanks in advance
Doc Stone

 

[chop house]

no

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

 

[watercam]

Go to the Berger Bullets web site and find their Barrel Twist Calculator. Fill in the info asked for and it will tell you if the bullet/barrel twist combo is stabilized or not. Pay attention to the elevation portion as your bullets will be flying faster with more elevation.

 

[Tokay444]

Go to the Berger Bullets web site and find their Barrel Twist Calculator. Fill in the info asked for and it will tell you if the bullet/barrel twist combo is stabilized or not. Pay attention to the elevation portion as your bullets will be flying faster with more elevation.

4000fps is 4000fps is 4000fps, regardless of elevation.

 

[FeMan]

Check the calculators as mentioned. They are will tell you what you need to know.

FWIW, increasing speed helps stability only slightly in a given twist, but not as much as you would think. Faster velocities certainly get the rpm up and increase the gyroscopic effect, but the forces acting to destabilize the bullet also increase with velocity in almost the same proportion. To get significant increases in bullet stability, you need to spin it faster without increasing velocity; i.e. go to a faster twist rate.

Altitude actually does matter in stability. The destabilizing affect is related to air density and decreases the higher you go, while the bullet rpm remains constant.

 

[timeout]

I have a 14 twist 22 BR Barrel and shooting 52 grainers at about 3750 fps.
I'm thinking of having this Barrel rechambered to 22 Dasher, which should
be pushing 4,000 fps. Question is , will this added speed make the 14 twist
less likely to stabilize the same 52 gr Bullets.
thanks in advance
Doc Stone

No. The additional fps makes it more likely to stabilize.

 

[Webster]

4000fps is 4000fps is 4000fps, regardless of elevation.

Correct: Elevation should be related to trajectory, not stability.

 

[RegionRat]

@voldoc02 Good question. I generally burn up things like Hornady 40 VMax in a 12 twist. The heavier (longer) I go, the worse my stability margin gets. I can fudge where I hunt due to the altitude since shooting at higher altitude adds stability margin compared to sea level. I haven’t added anything to the discussion yet, but I am wondering two things.

At a 14 twist, if you are stable at 3750 with a 52 grain, I will assume you will also be better at 4000. However, in a 0.224 dia with a length of about 0.717” and a BC of G1 0.717 using the Berger 52 gr flat base... the numbers are not looking good by their calculator. So that is why I will ask what bullet you shoot and are you stable now?

The Berger web site says this bullet requires a minimum of a 14 twist? I find this both good for you, but confusing for me? I’ve been marginal with heavier bullets using a 12 twist and I am confused by their recommendation being different between their calculator and their written description.

I think... if you are stable now, speeding up or shooting at higher altitude will be better, not worse. I just don’t understand the difference between their written recommendation, their calculator predicting poor values, and my own experience saying you should already be looking for a 12 twist or faster. I think a ring to the Berger techs would be a good idea to see why their calculator and their verbal are so vastly different?

 

[voldoc02]

"Just Ask=
It will be Given"
So much Great Info here
thanks so very much
Doc

 

[4xforfun]

Just remember.....this calculator is not GOD. If I was BUILDING a rifle I would consult the calculator to help pick the hardware. If I already OWNED a gun I would test.

Tod

 

[gunsandgunsmithing]

Doc, just the opposite. As has been mentioned already, speed helps stability with a given twist. Think in terms of RPM's and a fast spiral or a duck football pass. You know...a UT quarterback pass.

 

[K22]

Doc, just the opposite. As has been mentioned already, speed helps stability with a given twist. Think in terms of RPM's and a fast spiral or a duck football pass. You know...a UT quarterback pass.

Not saying this is incorrect, but with my 8" twist 223 Rem rifles, they shoot tighter at a lower velocity (about 2,900 f/s) with 55 grain bullets vs. my 12" twist 223's at about 3,100 to 3,200 f/s.

Not sure why this is - maybe it just a strange nuisance with my specific two Tikka 8" twist rifles but that what was revealed when I began load development with the Tikka's.

 

[dellet]

Not saying this is incorrect, but with my 8" twist 223 Rem rifles, they shoot tighter at a lower velocity (about 2,900 f/s) with 55 grain bullets vs. my 12" twist 223's at about 3,100 to 3,200 f/s.

Not sure why this is - maybe it just a strange nuisance with my specific two Tikka 8" twist rifles but that what was revealed when I began load development with the Tikka's.

Maybe because 3200 fps in a 12 twist is 192,000 rpm and in 8 twist is 288,000 rpm. That can be tough on plenty of bullets, more so in a hot barrel.

Back off to 2900 fps and it's only 261,000 rpm in an 8 twist. Not as likely to start coming apart.

 

[gunsandgunsmithing]

Not saying this is incorrect, but with my 8" twist 223 Rem rifles, they shoot tighter at a lower velocity (about 2,900 f/s) with 55 grain bullets vs. my 12" twist 223's at about 3,100 to 3,200 f/s.

Not sure why this is - maybe it just a strange nuisance with my specific two Tikka 8" twist rifles but that what was revealed when I began load development with the Tikka's.

All I will say is that my response was directly relative to bullet stability and nothing else. There are lots of variables to why two barrels dont shoot the same.

 

[jelenko]

Correct: Elevation should be related to trajectory, not stability.

Actually, it does affect stability. I think as someone else already mentioned, the density of the air has a significant impact on stability.
My B80.5's in an 8 twist are marginally stable at sea level but are fully stable at 1000 ft [which is where the match is held]