proper speed to stabilize pistol bullets

[oremike]

I was just wondering if there is a certain speed(fps) that certain bullets stabilize? I'm wanting to shoot hardcast 148gr DEWC's out of a 6" security six and use .357 brass. I'm hoping to shoot about 1000fps but am concerned the bullets might not group well if I push them too hard.

Read More

 

[Stomper]

If your shooting .357, 1000fps seems a little slow from what them puppies can zip along at...

 

[oremike]

I know I can pound them out there at yea haw velocities, but I was reading about rifle bullets going too fast, causing the tip to rise making them unstable and I was wondering if the same was true for beer can looking pistol bullets and at what speed that happens.

 

[BillM]

Most DEWC or HBWC's are fairly soft. They are made for low recoil, low velocity paper
punching. 1000 fps is pushing it a bit---you may get leading. Try backing off to
800 or so and work up.
If you want to push them faster without going to the expense of plated or jacketed,
try some of the current crop of poly coated bullets. Almost all of them are using the
HI-TEK Supercoat coatings from Australia, and you can push a soft lead bullet out to
darned near magnum velocities without issues.

 

[Member 5605]

If your shooting .357, 1000fps seems a little slow from what them puppies can zip along at...

Hard cast though..... Can't push them too fast.

Now jacketed...... 1900fps

 

[Jamie6.5]

Pistol bullets are rarely hard to stabilize because they're so short. Don't worry about it. Load 'em up and shoot 'em.

 

[oremike]

Near as I can tell these soup can shaped projectiles should be kept below the speed of sound so I should be just fine around 1000 fps.

 

[noylj]

Consider a jet designed to break the sound barrier. Now, consider a wadcutter.
Please note: DON'T ever take ANY L-HBWC over 800 fps. Never, ever.

 

[Certaindeaf]

1000 should make for a good field/plinking load with that weight/bullet. WC's, while often being unbelievably accurate out to 50-75 yards, count yourself lucky if they don't go all to pot out at 100 or so.

to some posters..
And lots of handgun bullets can and do tumble like crazy in flight.. it all depends on the rifling rate, length of bullet and speed.
And further, SWC's are pretty blunty (not like a jet.. lol) and they've been driven into game and targets for considerable time now.. at well beyond Mach1 using simple slightly alloyed lead. And they're good/accurate out at pretty darn long range.

 

[ditchtiger]

Speed does not stabilize bullets, it is the rate of twist.

 

[Certaindeaf]

Speed does not stabilize bullets, it is the rate of twist.

Standard .22lr twist rate is about 1:16, .223 is about 1:9.. the main difference between the two is the speed of the bullet. Speed is a factor to consider regarding twist rate/stabilization of a bullet.

 

[noylj]

>Standard .22lr twist rate is about 1:16, .223 is about 1:9.. the main difference between the two is the speed of the bullet. Speed is a factor to consider regarding twist rate/stabilization of a bullet.

The main difference between .223 and .22LR is the weight of bullet being stabilized and the length the bullet and the construction of the bullet and the bearing length of the bullet. Gee, maybe there really isn't that much similarity between them.
Precision Pistol centerfire shooting is usually done at 650-750 fps for 25-50 yards.
9mm pistol have a twist rate of 1:16 to 1:10, yet, for accuracy, they need to be about 1:25 to 1:35--talk to the folks in NRA Precision Pistol trying to get 9x19 to shoot accurately for competition against real guns like .45 Autos.
Most pistols could probably use a slower rate of twist, but they are almost all somewhere between 1:16 and 1:10, no matter what. Most pistol bullets have more in common with round ball and minnie ball than rifle bullets.

 

[Certaindeaf]

>Standard .22lr twist rate is about 1:16, .223 is about 1:9.. the main difference between the two is the speed of the bullet. Speed is a factor to consider regarding twist rate/stabilization of a bullet.

The main difference between .223 and .22LR is the weight of bullet being stabilized and the length the bullet and the construction of the bullet and the bearing length of the bullet. Gee, maybe there really isn't that much similarity between them.
Precision Pistol centerfire shooting is usually done at 650-750 fps for 25-50 yards.
9mm pistol have a twist rate of 1:16 to 1:10, yet, for accuracy, they need to be about 1:25 to 1:35--talk to the folks in NRA Precision Pistol trying to get 9x19 to shoot accurately for competition against real guns like .45 Autos.
Most pistols could probably use a slower rate of twist, but they are almost all somewhere between 1:16 and 1:10, no matter what. Most pistol bullets have more in common with round ball and minnie ball than rifle bullets.

Whatever you are trying to say, velocity is a factor to consider regarding optimum twist rate/stability.. otherwise, velocity would be a constant in any twist rate calculator.. and it is not.

http://www.bergerbullets.com/twist-rate-calculator/

 

[ditchtiger]

Standard .22lr twist rate is about 1:16, .223 is about 1:9.. the main difference between the two is the speed of the bullet. Speed is a factor to consider regarding twist rate/stabilization of a bullet.

Weight is the determining factor for twist needed. The heavier the is in relation to its diameter the faster spin it needs to stabilize. 22lr's are 30-40 grains, .223 go from 50 to 80 grains with twists as fast as 1:7.

 

[Certaindeaf]

Weight is the determining factor for twist needed. The heavier the is in relation to its diameter the faster spin it needs to stabilize. 22lr's are 30-40 grains, .223 go from 50 to 80 grains with twists as fast as 1:7.

The determining factor? Then hold everything constant save the velocity in any twist calculator. Change it from 1000 to 3000fps. badabingo.
http://www.bergerbullets.com/twist-rate-calculator/

 

[ditchtiger]

Change it from 1000 to 3000fps. badabingo.
http://www.bergerbullets.com/twist-rate-calculator/

It does not work that way. Its distance and RPM, not speed+RPM. A rifle that likes a lite bullet, 1:12, at 1000 FPS. The bullet will have rotated 1000 times at 1000 foot mark. Next, a heavier bullet that needs 1:6 to stabilize shot out of the same gun but at 2000 FPS. At the 1000 foot mark it will only have rotated 1000 times. No matter how fast it's shot RPM's at distance will not change.

 

[Certaindeaf]

It does not work that way. Its distance and RPM, not speed+RPM. A rifle that likes a lite bullet, 1:12, at 1000 FPS. The bullet will have rotated 1000 times at 1000 foot mark. Next, a heavier bullet that needs 1:6 to stabilize shot out of the same gun but at 2000 FPS. At the 1000 foot mark it will only have rotated 1000 times. No matter how fast it's shot RPM's at distance will not change.

We're talking about stability of a particular projectile here and then changing its velocity/speed only. Notice what happens.

 

[oremike]

Here's a follow up, shot 2 loads back to back alternating back and forth at 2 targets side by side. shot 4 cylinders of each load, left target was the lighter load right target was the heavier. I then shot 12 rounds of each over the chronograph keeping the strings separate. All shots fired from the same 6" Security Six. The first load was aprox 900 fps and shot aprox a 2" group, it's been my go to load. Second load was 1/2gr more powder so was going aprox 950 fps and shot a group half the size of the first. Looking at the chronograph data the extreme spread dropped from 103 to 54 and the standard deviation dropped from 26 to 18. I think I'm on to something here and will shoot this in my other .357 to see if it likes this load as well. If I get similar results with the GP-100 I might bump the load one more 1/2 gr. and see what happens there.

 

[OutlawHoss]

It does not work that way. Its distance and RPM, not speed+RPM. A rifle that likes a lite bullet, 1:12, at 1000 FPS. The bullet will have rotated 1000 times at 1000 foot mark. Next, a heavier bullet that needs 1:6 to stabilize shot out of the same gun but at 2000 FPS. At the 1000 foot mark it will only have rotated 1000 times. No matter how fast it's shot RPM's at distance will not change.

The 1:6 at 2000 fps actually will have rotated 4000 times at 1000 feet (it's spinning twice as fast, at twice the speed) and will likely be more stable, longer. And just to nit pick a bit more, if we're talking r(evolutions) p(er) m(inute) (which is the unit used in bullet stability formulae, the formula being: MV(12/rate of twist)60) than the 1:12 1000fps bullet is doing 60,000 rpm, and the 1:6 2000fps is doing 240,000 rpm. Of course that's notwithstanding drag, gravity, and loss of speed (inertia!) etc., which increases exponentially with time and distance, which is unique to the size, length, profile, and weight of the bullet; and thus all the ensuing fun with ballistics!

Bullet stability is a product of all of the above factors, i.e., rate of twist, speed, length of bullet, weight of bullet, design and quality of bullet. Those factors depend on other antecedent factors, like powder burn rate, length of barrel, bullet depth, and on and on.
http://www.accurateshooter.com/technical-articles/calculating-
bullet-rpm-spin-rates-stability/

If one uses JBM's website and select the spin drift version of their ballistic calculator, you can get a spin stability product in the results. Spin stability of 2 or greater is considered good. As any reloader will tell you, every gun is different; so with all the internal ballistic factors, there are a lot of variables to work with and no simple go to answer as to what factor is singularly responsible for stability.

(For the O.P.) So unless you're reloading rifle competition rounds, or doing serious pistol competition, the popular loads in any reputable reloading manual are going to work as most have been around a long time and are pretty well vetted.

If you really want more accuracy than that out of a pistol, I'd think about getting a rifle instead!

 

[AMProducts]

Here's a follow up, shot 2 loads back to back alternating back and forth at 2 targets side by side. shot 4 cylinders of each load, left target was the lighter load right target was the heavier. I then shot 12 rounds of each over the chronograph keeping the strings separate. All shots fired from the same 6" Security Six. The first load was aprox 900 fps and shot aprox a 2" group, it's been my go to load. Second load was 1/2gr more powder so was going aprox 950 fps and shot a group half the size of the first. Looking at the chronograph data the extreme spread dropped from 103 to 54 and the standard deviation dropped from 26 to 18. I think I'm on to something here and will shoot this in my other .357 to see if it likes this load as well. If I get similar results with the GP-100 I might bump the load one more 1/2 gr. and see what happens there.

Keep at it, maybe go +/- another .2gr and this load may tighten up a bit more. I tend to notice there's a sweet spot with most bullet/powder combos that will allow you to drop the SD down to single digits. my .45ACP load has an SD of 4, it's stupid accurate.