Bullet rotation speed on hunting bullets???

G

gt40

Guest
I was told that the faster a hunting bullet spins the more damage it creates when hitting game. Does this seem logical and do you think it is true? Since a 1 in 8" twist spins a bullet faster than a 1 in12" twist at the same velocity would the 1 in 8" do more damage?. Does the spin slow down with the same rate as the velocity? :confused:

gt40
 
Yes...it is a basic trueism...depends on bullet shape and jacket thickness...using twist to spin a bullet for more "frangibility" will work, but may come at a cost to accuracy and possible bullet failure (blow-up) when you go to far ...I remember shooting Sierra .224 60 grain hollow points out of my 22-250 (14 twist) and had clean pass-thruoughs on prarie dogs about 20% of my hits...but I put the same bullet in my .223 (12 twist) and it would blow them up on impact...and a a slightly lower velocity...
 
No hiding place from new U.S. Army rifles that use radio-controlled smart bullets

This is the new Guided Bullet the Army is using. Timed to blow up at a given distance.
No hiding from this baby.
NewGuidedBullet.jpg

NewRifle2.jpg
 
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A bullet loses velocity much faster than it loses rotational speed.

Say that an average deer is 12" from side to side. A 10 twist barrel means that your hunting bullet will make one to two revolutions if it goes completely through. Hardly the buzz-saw effect you might imagine. It would seem to me that bullet expansion, transferring it's energy to the deer, would be much more effective.

Am I missing something?:confused:

Ray
 
Cheechako said:
A bullet loses velocity much faster than it loses rotational speed.

Say that an average deer is 12" from side to side. A 10 twist barrel means that your hunting bullet will make one to two revolutions if it goes completely through. Hardly the buzz-saw effect you might imagine. It would seem to me that bullet expansion, transferring it's energy to the deer, would be much more effective.

Am I missing something?:confused:


Ray
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As it was explained to me is that because of the spinning when the bullet comes in contact with a "deer" it would disrupt the bullet more violently than if it was spinning slower. It "kind" of seems possible to be true.

gt40
 
"I was told . . ."

Some guy said . . ."

Whenever you see (hear) this, turn on your cynic switch. What follows may be true, but as a generality, you could get rich betting the other way.
 
I seem to recall that the buggers went down about the same when I hit them with a .45 calibre ball from a 60 twist barrel.

I was told that where you put it is most important. :cool:
 
gt40 said:
I was told that the faster a hunting bullet spins the more damage it creates when hitting game. Does this seem logical and do you think it is true?


Replacing the word "bullet" with "broadhead" will make the above statement true. I believe someone has their sport disciplines mixed up.
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As it was explained to me is that because of the spinning when the bullet comes in contact with a "deer" it would disrupt the bullet more violently than if it was spinning slower. It "kind" of seems possible to be true.

gt40
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The fast for bullet weight 1:10 twist of the Springfield and M1917 barrels was believed to be why the WW1 era .30-06 and the M2 Ball were so lethal.
The 1:10 twist was adopted when the .30 of 1903 used a 220 gr bullet, They kept the fast twist since it didn't seem to adversely affect accuracy of the 150 gr bullets and allowed use of heavier bullets should they adopt a heavier bullet later on, as they did for a short while with the 175 gr M1 Ball.
The M14 was given a slower twist better suited to the 144-150 gr bullets of 7.62 M80 Ball.

The German Gew 98 also had a fast twist coupled with a lightweight bullet of around 150 gr. These were also considered to be very lethal, with some dramatic wounding effect.

Some hunters prefered to use .30 150 gr FMJ Ball over heavier soft nose bullets, the lighter bullet expending more of its energy in the wound with less wasted by a through and through wound.

The velocity of a bullet in air doesn't govern how many times a bullet can rotate or tumble in flesh. The bullet striking flesh is being decelerated very rapidly and 5.56 bullets can tumble six or more times in the human torso, usually breaking into small fragments.
Depending on bullet construction and range a .30 or 7.62 150 gr FMJ can also fragment in the torso with devastating effect.
Jacket heating by gas blowby can increase fragmentation. A heated jacket combined with a quick twist lets centrifical force aid in separating core from jacket.

PS
Excessive rotational speed would likely increase duration of jaw at close ranges. The more jaw the more tumbling effect in the wound.
 
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As this thread illustrates very clearly, if you want clear answers then you must read a book or two. Some of the opinions expressed here are frankly "strange" IMO.

To address the original post with my opinions;

#1, sometimes
#2, sometimes
#3, no

beyond these three generalities lie a gamut of specifics.

Refine your questions and you might get more specific answers.

al
 
I know when I changed..........................

from a 14" to a 12" twist in my .22-250 the results with the Sierra 52BTHP favored the 12" twist. But, the 52gr was never supposed to be a hunting bullet, according to Sierra.
When I compared the difference (in a 12" twist) in lethality between the 52 Sierra and the 53 HornadyFBHP the difference was dramatic, and left no doubt as to which twist AND bullet was superior in execution. :eek: The Hornady 53 in the 12" twist had it ALL over the Sierra.
 
Am I missing something?
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Yes.......The bullet does not pass through the deer at anything near muzzle velocity, therefore........... it spends much more time IN the deer, but it doesn't stop rotating..........therefore it releases it's rotational energy within the deer. But this energy is very small and a bullet spinning at 250,000rpm have very little improved performance from on spinning at 175,000rpm...on a deer sized animal.......

Now on Prairie Dogs its a bit of a different story......I've shot PDs with a 6mm Ackley and 55 grain bullets in a 1-7.5 twist rifle. Absolutely amazing what happens. Do the math.....4000fps at 7.5 twist......only the best bullets would even stay together under these conditions.......
 
RoyB said:
Yes.......The bullet does not pass through the deer at anything near muzzle velocity, therefore........... it spends much more time IN the deer, but it doesn't stop rotating..........therefore it releases it's rotational energy within the deer. But this energy is very small and a bullet spinning at 250,000rpm have very little improved performance from on spinning at 175,000rpm...on a deer sized animal.......

Now on Prairie Dogs its a bit of a different story......I've shot PDs with a 6mm Ackley and 55 grain bullets in a 1-7.5 twist rifle. Absolutely amazing what happens. Do the math.....4000fps at 7.5 twist......only the best bullets would even stay together under these conditions.......
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I've seen high speed photos of a .220 Swift bullet disintegrating in mid air a foot or two beyond the muzzle at 4,000 FPS. Bullet construction just wasn't up to those speeds.

Construction is a deciding factor. Some bullets fragment on impact and others don't. A German 7.62 NATO bullet was pulled from production after a few high profile police marksman shootings. Those bullets, due to an error in jacket manufacture, exploded in the body producing horrendous wounds that shocked the public. Velocity and twist were within normal specifications.
 
Anybody remember the 358 Win. ? If I recall, it had a 12 twist, ( something that has always impressed me, when considering it) when most other barrels for the .358 caliber were a 16. Obermeyer rebarreled my .760 Rem. slide to a 35 whelen with a 14 twist.
More pressure ? More velosity ? It would seem so...
 
Early experiments on barrel heating were done using bullets driven down the bore by a hydraulic ram, to eliminate the effects of propellent heat transfer.
I'll have to look up the results to be sure but IIRC they found that bullet friction did more to heat bore and bullet than any normal transfer of heat from the propellents.
Blowby on the otherhand could heat a jacket to the failure point, but required a very high flame temperature and excessive throat erosion such as was common with early double base powders with high nitro percentage and no effective thermal moderators.

When the SMLE rifle was first designed they found that the MkVI ammunition in the shorter barrel lost velocity compared to the longer LE barrel. They tried a very unusual fix.
The last 14 inches of the bore was lapped over sized by a few thousandths. The sudden relief of bullet to bore friction allowed the bullet to develop the same velocity in the shorter barrel as it had in the longer barrel. Accuracy was adversely affected, especially after a period of normal wear.

It would seem to me that a tighter quick twist would heat the bullet jacket more by friction, and put more stress on the jacket during engraving.
The Carcano used a progressive twist, starting out slow then becoming tighter towards the muzzle. This put less stress on the bullet during initial ebgraving when pressure was near peak.

The US 1903 .30 Government was noted for highly erosive propellents and excessive blowby after a few thousand rounds. Jacket separations were common until improved bullet manufacturing techniques were instituted. That was with the 220 gr bullet and 1:10 twist. Reduction in velocity was tried, and it reduced the incidence of separations.
The 1906 .30 with lighter bullet used a much lower temperature single base powder, which reduced erosion. Less bearing surface may have also been a factor.
 
RoyB said:
..........Now on Prairie Dogs its a bit of a different story......I've shot PDs with a 6mm Ackley and 55 grain bullets in a 1-7.5 twist rifle. Absolutely amazing what happens. Do the math.....4000fps at 7.5 twist......only the best bullets would even stay together under these conditions.......
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I can get behind this.....

My experience has been similar. Once you're blowing bullets apart (and the animal along with it) higher rotation adds a remarkable explosive component.

al
 
Fred J said:
No hiding place from new U.S. Army rifles that use radio-controlled smart bullets

This is the new Guided Bullet the Army is using. Timed to blow up at a given distance.
No hiding from this baby.
NewGuidedBullet.jpg

NewRifle2.jpg
Click to expand...

yo Fred..... I dunno as I'd call that a "guided bullet" as a simple waste of taxpayer dollars :)

All's this silly thing can do is airburst at a measured (lasered) distance. It really ain't too tricky at all and certainly doesn't turn or "follow" a target.

al
 
? 1
gt40 said:
I was told that the faster a hunting bullet spins the more damage it creates when hitting game.
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? 2 [/QUOTE]Does this seem logical and do you think it is true?[/QUOTE]


? 3 [/QUOTE]Since a 1 in 8" twist spins a bullet faster than a 1 in12" twist at the same velocity would the 1 in 8" do more damage?. [/QUOTE]

? 4[/QUOTE]Does the spin slow down with the same rate as the velocity? :confused:
[/QUOTE]

As this thread illustrates very clearly, if you want clear answers then you must read a book or two. Some of the opinions expressed here are frankly "strange" IMO.

To address the original post with my opinions;

#1, sometimes
#2, sometimes
#3, no
???????????
:confused::confused:
My experience has been similar. Once you're blowing bullets apart (and the animal along with it) higher rotation adds a remarkable explosive component:confused:

Some of the opinions expressed here are frankly "strange" IMO.
Indeed.
Waterboy
 
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