Bullet rotation speed on hunting bullets???

[Rustystud]

missing something

If a bullet is traveling 3000 fps and for simplicity at 1:12 twist. That would put the bullet turning at 3600 rps X 60 = 216,000 RPMs.

A bullet traveling 3000 fps hitting a mass like a deer puts a tremendous amount of dragg on a bullet. But has a much less effect on the spin of the bullet.

I would not know the declining velocity formula without knowing the sectional density of the deer. But bullets that strike objects are decreasing velocity at an exponential ratio to the loss of spin.

Spinning bullets that deform like solf points act just like a drill bit in distruction of tissue.

Bullets cause hydrostatic shock and physiogentic shock. This is not taking into effect the shockwaves that follow a bullet into the wound channel for each time the bullet has exceed the speed of sound.

A high speed video of a bullet impacting and proceeding through living tissue is quite impressive. I can't recomend going to the Walter Reed Hospital Museum in Washington DC. There are great displays of bullet wound trauma.

Nat Lambeth

 

[AJ300MAG]

This is not taking into effect the shockwaves that follow a bullet into the wound channel for each time the bullet has exceed the speed of sound.

Had a "friend" tell me that you don't have to actually hit something with a 750gr .50 cal bullet, the shockwave off the bullet is enough to implode someone's head if it passes by close enough. Sad thing is this idiot also owns a Barrett...

Another friend who's a ballistic missile designer laid that little theory to rest.

 

[alinwa]

? 1

? 2

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?
[/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
???????????

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

Some of the opinions expressed here are frankly "strange" IMO.
Indeed.
Waterboy[/QUOTE]

Not sure why you're messing with my post lynn but prairie dogs aren't game animals.

al

 

[MilGunsmith]

In our testing at work in ballistic gelatin, we have found that twist makes a difference. We shoot identical loads thru different twist test barrels and watch it with three high speed cameras.

 

[Jim S]

I guess in varmit bullets I could see a difference in performance due to a faster twist if EVERYTHING else is equal, (velocity, land engraving deformation, ect) In most hunting bullets, bonded jackets, thicker jackets and solid copper. I can hardly fathom a noticable difference in internal body damage.

If my 160 grain AB in a 7mm needs a 9 twist, I guess an 8 twist would do what 11% more damage?

Or I could get a 4.5 twist and turn them deer inside out and never need to gut another one? Oh but my pressures would be so high I guess I would have to run it at 2200 fps muzzle velocity.

I just built a 308 specifically for 110 v-maxes with a 17 twist to explode varmits. Now I should have put it in a 8 twist because thats what explodes varmits??

I'm running 110V-max at 3450 fps in a 17 twist, Most guys on the net max out at 3100 with a 10 twist factory barrel. So which is more important the extra 350 fps or the faster twist?

Typical high velocity varmit bullets are fragged out within 2 inches of penetrating the target, so the bullet made what one quarter of a rotation in the animal? Or does the wound channel look like a debree swirl in a funnel cloud as the frags contine to rotate in an ever expanding funnel?

At 3400 fps how much more violent can bullet expansion get?

So go hunt with your 223 and 55 grain B-tips in an 8 twist, I'll hunt with the 22-6mm and 55 b-tips in a 14 twist. Your RPMs might be higher , but my P-dog pieces will fly higher.

 

[Lynn]

Alinwa
I wasn't messing with your post at all.You gave 3 answers to his 4 questions so I didn't know what you were agreeing with or disagreeing to.
He said hunting bullets for deer in his original post with the only variable being the twist rate.
The faster twist will cause more fragmentation but it will not be as big of a difference as upping the velocity several hundred feet per second would be.
Velocity gives you those spectacular flips/destruction on varmints not the barrels twist rate.Hits that come in low is what sends a squirrel/prairie dog flying.
Waterboy

 

[mturner]

I can tell you that from actual experience, that when you slow down the twist rate in a hunting rifle, the bullet becomes considerably less explosive. Here is an example: a 125 gr Balistic Tip at 3500 fps in a 10" twist is 252,000 RPM, and with a 16" twist it is spinning at only 157,500 RPM. I have used both on deer sized game and the results were very different. A body shot with the 16" twist, and the bullet goes all the way through the deer, while the 10" twist blew up causing considerable damage. A neck shot with the 16" twist resulted in about a 2" diameter exit wound, and with the 10" twist about a 5" exit wound.

I have used this for some time to do two things, improve the accuracy of a hunting rifle, and to get far better penetration with what is considered to be cheap bullets, or bullets that were not intended for anything more than varmints. This just shows how modern improvements in BR technology can be applied to the hunting world. My 30-338 Win Mag Elk rifle has a 16" twist, so I don't have to shoot the high end bullets, but still am pleased with the performance.

Michael

 

[wyrhare]

257 condor

I guess in varmit bullets I could see a difference in performance due to a faster twist if EVERYTHING else is equal, (velocity, land engraving deformation, ect) In most hunting bullets, bonded jackets, thicker jackets and solid copper. I can hardly fathom a noticable difference in internal body damage.

If my 160 grain AB in a 7mm needs a 9 twist, I guess an 8 twist would do what 11% more damage?

Or I could get a 4.5 twist and turn them deer inside out and never need to gut another one? Oh but my pressures would be so high I guess I would have to run it at 2200 fps muzzle velocity.

I just built a 308 specifically for 110 v-maxes with a 17 twist to explode varmits. Now I should have put it in a 8 twist because thats what explodes varmits??

I'm running 110V-max at 3450 fps in a 17 twist, Most guys on the net max out at 3100 with a 10 twist factory barrel. So which is more important the extra 350 fps or the faster twist?

Typical high velocity varmit bullets are fragged out within 2 inches of penetrating the target, so the bullet made what one quarter of a rotation in the animal? Or does the wound channel look like a debree swirl in a funnel cloud as the frags contine to rotate in an ever expanding funnel?

At 3400 fps how much more violent can bullet expansion get?

So go hunt with your 223 and 55 grain B-tips in an 8 twist, I'll hunt with the 22-6mm and 55 b-tips in a 14 twist. Your RPMs might be higher , but my P-dog pieces will fly higher.

Interesting topic

Years ago I purchased a .257 condor with 9 boxes of Norma factory brass and 600 Norma 160 grain bullets

I rechambered it to .257 Weatherby mag to avoid the cost of custom reloading dies. The last load used was 66 grains of Imr 7828 which averaged close to 3100 fps. Norma made the 160 grain hollow point with a copper plated steel jacket (Yes it is magnetic)

Measurements of the barrel indicate a 1 in 6.5 inch twist, .250 by .2565 bore.

Having hunted for 50 years using many different calibers on varmints and large game animals I have never witnessed such violent wounds to animal tissue . Entry and exit wounds are massive and other than fragments I have yet to recover a spent bullet.

Bullet construction might be questioned but understand that it shoots through both shoulders of a moose or black bear.

The .257 is a wall queen now because I feel it is over kill and a meat waster. I can only conclude that the length and the high rotation of the bullet are the reason for its excessive terminal ballistics

Rick

 

[Joe S]

Just for fun....a bullet with no velocity still spinning
http://www.youtube.com/watch?v=foZlciP6gUQ

 

[Lynn]

MTurner
I've shot 55 legal bucks not a single doe,spike or fawn and no night hunting with a spotlight or shooting them in the headlights.The 6X6 elk hanging on my wall was shot with a 243 only because it was at the right place at the right time.
If your after huge amounts of bloodshot meat and big holes 3500 fps with a lightweight bullet will get you there.
When the 220 Swift came out they were getting amazing kills on grizzly bears with it and even took the time to write articles about it for the whole world to read about.
On deer type game with actual deer hunting size bullets you won't be able to skin the animal out and say what twist rate killed it.
If your hunting deer with a 3500 fps or faster load and lightweight bullets an experienced hunter will be able to tell you so.
Shoot a deer or two with a 300 Whisper in a 7 twist barrel and note what the entrance and exit wounds look like.Calculate those 2 bullets rpm rate then using a 14 twist barrel at the same rpm rate but with a higher velocity shoot 2 more deer.When you compare the wounds both at the same rpm you'll better understand what I am saying.
Waterboy

 

[John Kielly]

Just for fun....a bullet with no velocity still spinning

Cute. Lousy gun handling, but cute.

 

[mturner]

Lynn,
All I'm saying is that the slower twist rate DOES cause the bullet to penetrate better and do less damage. I have shot enough deer to witness first hand what happens. Not trying to brag or anything, but after hunting for 40 years, the number of deer I've taken has been in the hundreds. I have lived most of my life in a five deer per year county, and tagged out every year. The thing is I have also been on a lot of hunts where deer needed to be thinned out. We would be told things like "we need to take somewhere around 200 dear this week. Now when I mention these results, I'm only telling people that there is a way to get better performance with slower twist. I have wasted very little meat when hunting with high velocity rounds. Nine out of ten deer I have taken since the day I started hunting were neck shots. I have never had a deer mounted, so a head or a neck shot has never been a problem. Now the way I see it, a 300 Whisper doesn't make enough velocity to really cause a bullet to expand at near the rate that I'm used to seeing, but I can say that I have even tested 125 gr bullets at 3100 fps out of a 30-30 Winchester, and when I slowed the twist down on that rifle from a 10" twist to a 14" twist, I was almost disappointed with the lack of expansion, especially when the bullet didn't strike any bone. At the same time I have also witnessed times when hunters that were not very good at placing their shots, did a tremendous amount of devastation to the animal, and wasted a whole lot of meat, using light bullets at high velocities and fast twist rates. So to agree with what you said, cartridges like the 220 Swift aren't the best choice for everyone.

Michael

 

[Lynn]

MTurner
If you shoot a 180 grain Sierra out of a 7 twist 300 whisper at 1500 fps it will be spinning at 154,285 rpm.If you shoot the same bullet out of a 300 winchester magnum at 3000 fps using a 14 twist barrel it will once again be traveling at 154,285 rpm.
In my experience the faster bullet will always do much more visible damage.If you now switch to a 10 twist barrel on your 300 winchester magnum and keep the bullet at the same 3000 fps I've never been able to see the extra 61,000 rpm variance on the animal.

I hunt blacktails and mule deer and the only head or neck shots I've ever made were missed placed shots.I generaly only shoot for the front shoulder.

If you've actually shot 200 legal bucks I tip my hat to you.
I've hunted on some of the best ranches on the westcoast since my 12th birthday and nobody out here has ever legaly killed 100 bucks that I know of.If you remember the TV show Bonanza with Hoss,Ben,Adam and Little Joe set on the Ponderosa Ranch? I actually hunted the ranch they owned and it was called the RockPile Ranch.We averaged 63 legal bucks a year on that ranch and in 3 years time shot over 1500 pigs for the 20 full time members and there guests.We lost our lease after the third year because we weren't shooting enough pigs.
Waterboy

 

[Swamp Fox]

Consider for a moment. If a bullet is shot at 3000fps and 4000fps out of a 1 in 12 twist barrel it will still spin once in 12 inches.
If the same bullet is shot from two different barrels, one a 1 in 12 and the other a 1 in 9, will the difference between 1 rotation as it passes through a deer vs 1.3 rotations as it passes through make one a stastically better killer than the other?
A bullet isn't "buzz sawing" through an animal unless you think 1 to 1 1/2 rotations is a buzz saw.

 

[mturner]

Lynn,
There are a lot of assumptions made here. You use the word "legal". What is your definition of a "legal buck"? In Texas where I hunted, there was little definition there. I said I lived in a 5 deer county. I could take "any buck" or "any doe". There weren't a lot of rules. Just no spotlight, and something like the hunt was over 30 minutes after sunset. There was even extended seasons for extra doe and spikes. I haven't even come close to taking 200 legal bucks, if it means something like 3 points on each side. What I've learned about bullet expansion was not limited to only one sex. I've only hunted pigs for about 30 minutes of my life. I still have about six of the eight pigs I killed in the freezer. Now I live in New Mexico where you can do a lot more game watching and very little hunting. Oh, I guess if I was very rich or very wasteful, I could go for the Elk-Buck combo offered by the Indians on the reservations. It cost around $11,000. I have only spent about $800 in hunting license for my whole lifetime. Just seems hard to justify. I'm quite certain Lynn, that your hunting experiances have far exceeded mine. I don't think I've ever come close to any trophies. I've just filled freezer after freezer with meduim size bucks and doe. Living in New Mexico can be depressing after hunting in Texas. There seems to be a much better hunting selection here, if you are ever lucky enough to get drawn. I've never been drawn to hunt this state yet.

Michael

 

[Joe Maisto]

Gentlemen;

I have read the above with great interest. I do not intend to argue who is right or wrong on any of it, interesting as it is.
What I do know from my own taking of white tail deer in Wisconsin is this.
The only shot that will kill a dear "in it's tracks" is a head shot. Furthermore, If the opportunity presents it self, I will always place my shot in the rib cage towards the front, thereby taking out the lungs. Trust me...with a .270 and a 130 gr. speer or equivilent in a factory barrel, you will waste no meat, break two ribs, and you will find the animal laying dead within 50 yds.
This rule also applies to most calibbers within a given distance. That means...not shooting across a bean field.

 

[pbike]

In It's tracks!

What I do know from my own taking of white tail deer in Wisconsin is this.
The only shot that will kill a dear "in it's tracks" is a head shot. Furthermore, If the opportunity presents it self, I will always place my shot in the rib cage towards the front, thereby taking out the lungs. Trust me...with a .270 and a 130 gr. speer or equivilent in a factory barrel, you will waste no meat, break two ribs, and you will find the animal laying dead within 50 yds.

I have been reading this thread for quite a while and I knew I would see the "In It's Tracks" phrase come up. Don't all Deer, Antilope, Moose, Elk, Bears, etc. all ground dwelling footed animals die "In their tracks"? I mean where else would they die no matter how well or how poorly they are hit, when they die, they are usually pretty damn close to the tracks they just made. Aren't they?

 

[alinwa]

Alinwa
I wasn't messing with your post at all.You gave 3 answers to his 4 questions so I didn't know what you were agreeing with or disagreeing to.
He said hunting bullets for deer in his original post with the only variable being the twist rate.
The faster twist will cause more fragmentation but it will not be as big of a difference as upping the velocity several hundred feet per second would be.
Velocity gives you those spectacular flips/destruction on varmints not the barrels twist rate.Hits that come in low is what sends a squirrel/prairie dog flying.
Waterboy

Thanks for the clarification but it looks like we'll definitely disagree on this one!

I've hunted varmints with the .243AI, 22-250, 22BR and 6BR in all the twist rates from 14 to 7.5 and across the boards the tighter twists produce more mist when fired at the same velocity.

Some points gained from this exercise;

#1, tighter twist produces bigger pop all else being equal.

#2, tighter5 twist does NOTHING to pressure/velocity that can't be explained by other differences. For instance I had a Shilen 8" that was "slower" for a given powder charge than the Krieger 14twist...... and then I chambered up a loose twist Shilen and it was also slow. And later I've had many "fast" tight twist barrels. In short it is currently my belief that any twist can reach the velocity of any other.

#3, tight twist barrels can be hideously accurate with certain light Match bullets.

#4, lastly and most importantly HIT 'EM HIGH!!!! You gotta' SUCK 'em outta' their holes!!! It is my strong opinion that you need a chest/neck shot on a posting dog/squirrel for best effect with a head shot still being SAFE in that the li'l bugger doesn't crawl off into his hole but a solid center chest produces the most fireworks and highest count.

Ohh, and for big stuff like rockchucks/badgers/coyotes/marmots/groundhogs step up to a 300WSM with 100/125's at near-on 4000fps...... holey COW!!! Like throwing melons into a rotor blade....

al

 

[Joe Maisto]

Paul;

I had assumed most would know that..."in it's tracks" means without running off . As in...an instant kill . Perhaps the word "collapsing" might have been more appropriate ?

 

[alinwa]

What I do know from my own taking of white tail deer in Wisconsin is this.
The only shot that will kill a dear "in it's tracks" is a head shot. Furthermore, If the opportunity presents it self, I will always place my shot in the rib cage towards the front, thereby taking out the lungs. Trust me...with a .270 and a 130 gr. speer or equivilent in a factory barrel, you will waste no meat, break two ribs, and you will find the animal laying dead within 50 yds.

I have been reading this thread for quite a while and I knew I would see the "In It's Tracks" phrase come up. Don't all Deer, Antilope, Moose, Elk, Bears, etc. all ground dwelling footed animals die "In their tracks"? I mean where else would they die no matter how well or how poorly they are hit, when they die, they are usually pretty damn close to the tracks they just made. Aren't they?

Hey don't be knockin' on Sacred Redneck Hyperbole! Just last week I lost me wallet and looked for days..... finally found it, IN THE LAST PLACE LOOKED!!!

That said, I knew a guy in Minn'desoda who brought pictures of him gutting a deer standing up. Vertical shot from a tree-stand, muddy ground and a monstrous 45-70 handload allowed him to slap a little doe so deep in the mud that it didn't fall over..... I guess that deer "died in it's tracks."

al

Speaking of redneck verbiage...... I gener'ly hear about three kinds of deer; #1 is the "big doe." Number two is the "meat hunting" deer and then we come to number three, the "biggest tracks I ever saw!"