Mometum???...Energy???

[Eaglet]

From ballistic explorer I got this information:

[ QUOTE ]
Momentum
An indication of a bullet's knockdown power is momentum. Doubling either the weight (mass) or velocity of a bullet doubles its momentum. Clearly it's energy that makes bullets deadly to game, yet it's momentum that knocks game off its feet or knocks metal targets over.

[/ QUOTE ]

If that is true, then a 308 Winch. with 175 gr. bullet will produce about 2000 f/lb at 180 yards, most of us will agree that's good medicine for elk, the momentum would be about 57 lb-f/s which the 375 H&H with 260 gr. bullet and MV=2800 f/s accubond will produce the same momentum at around 760 yards even though the tables tells us it would only be 1365 f/lb. of energy. What are your views on this matter? Would the 308 Winch. kill it faster at 180 yards than the 375 H&H at 760 yards? Would you trust better the 308 Winch. at 180 yards or the 375 at 760?
Thanks in Advanced.

Javier O Moncada.

 

[wapiti13]

Eaglet, First off nothing short of a cannon ball will "knock game off its feet". This is a widely held misconception. If an animal is struck in the right nerve center (such as the spine), it will appear to be knocked over. Bullets kill bt disrupting normal body functions by cutting a path through the animal. Lung shots deprive the animal of air and breathing capacity, heart shots deprive the animal of blood flow, etc. That is why with the smaller calibers, expansion and penetration is so important. A light bullet going too fast will "explode" upon impact causing only surface damage with no penetration to vital organs, etc. The old "big bore" bullets made a large hole and they penetrated very well. They did not have hydrostatic shock like smaller high velocity rounds, but animals died. A very large argument over which type of bullet causes a better terminal result. One thing is pretty much universally agreed upon is that you must have a certain amount of penetration to be effective. A long standing argument is which is better: to exit or stop just under the hide? Energy does not kill animals per se, but rather the bullet causing a disruption of the body functions of the animal. Only a hit in the nervous system can cause a true muscle reaction that appears as "knockdown". Momentum does play a larger part on a steel target since the bullet must stay together and "push" against the target to knock it over. There are no body funtions to disrupt, so slightly different theory applies to steel vs. animals. Hope that this isn't too confusing. We primarily are concerned with live animals on this site and performance of bullets in bone, live tissue, etc. This is why the "bonded bullet" is causing such a stir. Better expansion, but also better penetration since the bullet stays together rather than breaks up and causes a better wound channel. Good luck. /ubbthreads/images/graemlins/smile.gif

 

[davewilson]

E,
give me the 308 at 180.i'll take momentum every time.

 

[ricka0]

[ QUOTE ]
<font color="purple">
Eaglet, First off nothing short of a cannon ball will "knock game off its feet". This is a widely held misconception. </font>

[/ QUOTE ] Thanks to the movie industry. The shooter gets more momentum applied to her shoulder than the target gets (because the bullet is transferring(loosing) momentum to the air molecules it plows thru.

I did regularly knock gophers off their feet with my '06 however /ubbthreads/images/graemlins/smile.gif

 

[Charles A]

[ QUOTE ]
Eaglet, First off nothing short of a cannon ball will "knock game off its feet". This is a widely held misconception. If an animal is struck in the right nerve center (such as the spine), it will appear to be knocked over. Bullets kill bt disrupting normal body functions by cutting a path through the animal. Lung shots deprive the animal of air and breathing capacity, heart shots deprive the animal of blood flow, etc. That is why with the smaller calibers, expansion and penetration is so important. A light bullet going too fast will "explode" upon impact causing only surface damage with no penetration to vital organs, etc. The old "big bore" bullets made a large hole and they penetrated very well. They did not have hydrostatic shock like smaller high velocity rounds, but animals died. A very large argument over which type of bullet causes a better terminal result. One thing is pretty much universally agreed upon is that you must have a certain amount of penetration to be effective. A long standing argument is which is better: to exit or stop just under the hide? Energy does not kill animals per se, but rather the bullet causing a disruption of the body functions of the animal. Only a hit in the nervous system can cause a true muscle reaction that appears as "knockdown". Momentum does play a larger part on a steel target since the bullet must stay together and "push" against the target to knock it over. There are no body funtions to disrupt, so slightly different theory applies to steel vs. animals. Hope that this isn't too confusing. We primarily are concerned with live animals on this site and performance of bullets in bone, live tissue, etc. This is why the "bonded bullet" is causing such a stir. Better expansion, but also better penetration since the bullet stays together rather than breaks up and causes a better wound channel. Good luck. /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

Very good post!

 

[Eaglet]

wapiti13,

[ QUOTE ]
Momentum does play a larger part on a steel target since the bullet must stay together and "push" against the target to knock it over. There are no body funtions to disrupt, so slightly different theory applies to steel vs. animals.

[/ QUOTE ]

I never did look at it that way, but it simply makes a lot of sence. I would still like to see what would be your choice in the example given.
Thanks.

 

[wapiti13]

Eaglet, Having shot IHMSA for over 20 years, I have shot so many bullets on steel that I lost count. Handgun bullets vs rifle bullets have similar problems. Long, heavy, slow bullets knock down steel better than light, fast bullets. "Dwell time" which could be defined as the actual time that a bullet has physical contact on the steel is very important. A light, fast bullet might have great energy on steel, but if it just blows up, it will not dependably knock over steel everytime. A heavier, slower, longer bullet maintains contact on the target for a longer time as it expands and pushes. Even full metal jacketed bullets "expand" on steel since they compress and squash down as they push on the target. This dwell time on the target lends itself to more dependable knock down. This is why many silhouette shooters used tough match grade bullets like the old Hornady match bullets. The forerunner to the A Max was a TOUGH bullet that expanded upon contact because of the hollow point, but mushroomed out very slowly and stayed on the target for a long period pushing all of the paper energy onto the steel. Using 162 7mm match bullets, I've peeled paint on targets that looked like I shot the target with a small softball (paint peeled down to the bare steel). This type of contact is not critical on animals because of penetration, but very important on a steel target that must be pushed over off its stand. Hopes this helps clarify steel vs flesh.

 

[Eaglet]

wapiti13, surely gives a person a lot to think about. Very interesting subject. Would you agree that If we have two heavy slow moving bullets, same weight, same speed, but one full metal jacket and the other one exposed lead in the nose, same distance,the lead exposed bullet would produce more momentum due to a possibly longer "dwelling time"?

 

[wapiti13]

Eaglet, Maybe. If the soft jacketed bullet was "tough", then it might stick longer on the target vs a true FMJ. Many of the hunting bullets in jackets aren't made to stick together on steel. Hitting a steel target is like driving your car head on into a wall. Something has to give. If the target starts to fall upon impact, your bullet has a better chance. But if wind if blowing from the back or the target is set wrong and leaning forward, it hesitates and doesn't move immediately. This is the test of your bullet. Sierra's early FMJs were really a jacketed bullet with the lead exposed on the rear and jacket rolled over. Upon impact, the lead would squirt out the back. That is why a "silhouette" FMJ was developed by Sierra where the jacket is more conventional with the cup covering the rear and folded over the nose with just a small spot of lead exposed on the nose area. Much tougher and harder to blow the bullet apart. As you can see, hitting steel is a totally different concept than animals, unless the target is the skull of a grizzly bear and you are trying to penetrate that thick bone. Then your problem besides penetration is using a bullet that does not have the tendency to skid along the bone and not bore through! Here point type,limited expansion, etc. all come into play. Oh well, what fun,experimentation, and research.

 

[Eaglet]

wapiti13, thank you! it's all very interesting. I appreciate your input.