While I am sure this has been hashed out many times, why not again?

Which is more inportant in penetration, velocity or bullet weight? If needed, break the question down into expanding versus non-expanding bullets.

I'm no physics expert, but my intuition tells me weight is more important (in the case of non expanding bullets) because it is a constant during terminal performance, whereas velocity erodes because of friction.

Anyway... your thoughts...

IMHO, both. The key is momentum, defined as the mass times the velocity. In other words, I feel that a non expanding .375 bullet of 200 grains and moving at 3000fps will penetrate the same as a .375 bullet of 400 grains moving at 1500 fps.

Obviously this assumes all other factors (diameter, expansion rate, etc.) are held constant, hardly an easy task in the real world!

In expanding bullets, bullet construction is more imporant then bullet weight. An example would be say a 165 gr barnes X bullet in a 300 win mag that will outpenetrate a typical 180 gr cup/core bullet. The reason for this is the barnes will keep nearly all of it's weight in tact, while the heavier cup/core bullet will loose upwards of 50% of it's weight, so hence be much lighter.

As far as velocity is concerned, bullet penetration will depend on how much the bullet upsets on impact. Increasing velocity will increase penetration to a point, and then penetration will start to decrease.

I'll go first w/ Paul on this one, bullet construction is #1, then weight then vel. My own tests in wetpack show this to be true:
A .45/300gr hard cast LFP @ 1000fps penetrates farther than any soft point I have tested, except the .423/400grWoodleigh, about 20" in wetpack. A 7mm/140grNBT @ 3000fps, less than 13". I'm sure penetration in flesh, while not the same, would be relevent.

Look up Norbert's posts on the Super Penetrator, and read his web page. Pretty much the definitive word on the subject of non-deforming penetration.

I agree with CDH on this one assuming all else is held constant. I'm not a physicist either but from what I recall from my classes in the subject, mass is required to maintain momentum. Weight and mass are NOT the same. That's why, all else being equal, the object with more mass will penetrate more. Take 2 bullets of the same caliber but with considerable difference in mass. Load them to the same velocity & do a penetration test and see which ones penetrate more. Bear in Fairbanks

It depends on what your trying to accomplish. For big tough hogs up close a granny speed puppy soft 250 gn speer from a 358 win is fine medicne.

But it certianly wouldnt be my first choice for Elk @ 250 yds or for deer @ 350.

Match your arms and loads to your quarry and hunting situation. The effectivness is as variable as the number of different approaches. I really dont think there is a single best way that covers all of the bases. That is why I reload.

With soft point or expanding bullets, expansion will cause less penetration. Bullet construction and sectional density will promote more penetration. Bullet weight helps momentum as well.

Neither is as important as bullet construction.

SD and bullet construction are pretty imortant IMHO

If I am in doubt, I would rather have lower velocity and high sectional density, than low sectional density and high velocity. The latter puts a lot more demand on the bullet.

It is amazing how much a bullet will penetrate at lower velocity, regardless of what the Gun Rags claim. A lot of "gospel" I learned reading gun rags was dispelled as I gained more real world experience.

In a 30/06 if I don't have to worry about range being over 250 yds, I have been amazed at what a 220 grain round nose will walk thru.

A 175 grain SP in 7mm leaving the muzzle at 2000 fps will penetrate like most people wouldn't believe unless they saw the end results.

Shot placement, reasonable ranges and lower velocity has a lot going for it, with a lot of different bullet weights. Of course one has to live in the real world before you realize that, instead of Gun Rag Land.

Cheers
seafire

quote:

---

Which is more inportant in penetration, velocity or bullet weight? If needed, break the question down into expanding versus non-expanding bullets.

---

It all depends on the game at hand. It doesn't take much of any bullet to succesfully take Whitetails although, there are those folks that think you need a bullet that will go in their nose and come out the rear end. If we are talking Moose or African game, that is when bullet weight, construction, and velocity are the most important.

In theory the "Perfect" bullet would be one that penetrated though the animal, used all energy to damage organs, exited, and fell to the ground immediately. We just can't have that can we.

Good Luck!

Reloader

Energy = 1/2 *mass * Velocity^2

So things being equal a little bit of velocity helps WAY more than a little bit of weight.

Then you get into the "bullet form factor" (round vs. flat vs. pointy) and the difference in hardness between the bullet and the target.

What was the question again???

Neither. The correct answer in comparing any two bullets with the same construction is Sectional Density times Velocity. Those of us who have designed inert projectiles to shoot THROUGH tanks call this SDV.

You need to shoot a 180 gr 300 Mag 3000 fps to match the penetration of a 6.5mm 160 grainer at 2500 fps. Its a bigger hole, that's all.

I was told one of the reasons the SDV is applied to metal penetration is damage to the projectile itslef as it penetrates, thus favouring a longer one that can keep going.

Harald, a weapon systems engineer who used to post here did a lot of tests of his own and got graphs from memory that showed peentration decreasing at certain velocities for solids and then increasing again.
Also in cases no difference from increasing the SD.

It was well over my head. I'm no engineer or designer of anything but he certainly turned things on their ear around here for a while.

Karl.

Some of the arguments about low velocity with high penetration make about as much sense as rolling a 45-70 bullet in oats and dropping it in front of a herd of cape buffalo. By the time a buff craps it out you will have had 100 percent head to tail penetration at LOW velocity so it will undoubtedly roll over dead.

86thecat,

That's a good one!

Reloader

quote:

---

Originally posted by 86thecat:
Some of the arguments about low velocity with high penetration make about as much sense as rolling a 45-70 bullet in oats and dropping it in front of a herd of cape buffalo. By the time a buff craps it out you will have had 100 percent head to tail penetration at LOW velocity so it will undoubtedly roll over dead.

---

The only part I understood about this analogy was the CRAP part.

seafire

The key to penetration in living animals is sectional density. A rapidly expanding bullet from a high velocity round lowers it's sectional density and therefore it's Penetration.
Since SD is a product of its weight/Diameter squared a heavier bullet for a given diameter will have greater sectional desity.
Penetration in other mediums can be the opposite. A 545gr 45cal bullet with high sectional density and low velocity will knock over a 1/4 hardened steel silhouette target but will barely dent the steel. A 40gr 22 cal bullet at high velocity but low SD will poke a hole clean through the hardened steel plate, this is why 22 centerfires are banned on our Silhouette range. On live game the heavy 45 cal bullet will vastly outpenetrate the 40gr 22..............DJ

Seafire, My comment was meant in good humor just forgot to attach a smiley face to it. My point was even though penetration is important the bullet needs to do damage as it passes through the animal and a reasonably high velocity along with bullet shape, construction etc. contributes to a larger area of tissue damage. Here is an interesting link that was posted on AR previously. wounding ballistics
86thecat

86,

First: I thought the "45-70 rolled in oats...." line was hilarious. Well, maybe not to the "45-70 is the penetration king" folks. But I liked it.... if slow is so darned good, then may as well take it to the extreme! Do you think that bullet "tumbled" any during the pass thru?


Second:

quote:

---

While I am sure this has been hashed out many times, why not again?

---

Well for one thing there are enough components to killing power to put even the informed folks to the test, then you throw in the others, and then top it off with,
"The only thing hunters agree on 100%, is to disagree" and it becomes an exercise in futility.

Upside is it did bring in some good humor. Nice one '86!

EKM

quote:

---

Originally posted by 86thecat:
Seafire, My comment was meant in good humor just forgot to attach a smiley face to it. My point was even though penetration is important the bullet needs to do damage as it passes through the animal and a reasonably high velocity along with bullet shape, construction etc. contributes to a larger area of tissue damage. Here is an interesting link that was posted on AR previously. http://www.rathcoombe.net/sci-tech/ballistics/wounding.html
86thecat

---

86: It is I who didn't get my point across with a smile on my face. I was just adding a little humor there also.

Personally, I believe terminal performance begins with shot placement, gettting the bullet where it needs to be. I have my preferences of what I use in the field, because it works for me.

I have also come to believe in performance of certain bullets, that I use to not believe in, because that is what I was told by "experts".

A lot more miles under the front bumper have taught me, that 'experts' are not so expert, and to believe what I see for myself, not what some "expert" tells me I see.

Thanks for the apology or the clearing up what you thought I was thinking. NO problems here at all.

Cheers and good shooting
seafire

Bullet weight is important so long as the bullet keeps it after striking the medium. Velocity is important so long as it doesn't cause the bullet to lose too much weight or expand to too large a diameter. Weight retention & expansion characteristics are determined by bullet construction. Slow heavy bullets of standard construction often pentrate deeply because they don't shed as much weight or expand to as large a diameter as if launched at a higher velocity. The tradeoff for low velociy is typically a narrower, longer wound channel vs a shallower wider wound channel at higher velocity. You can play with bullet construction to always get penetration (i.e. bullet expands to a certain point and stops no matter what the velocity) in order to acheive desired results, but you will almost always be trading off width of the wound channel to get penetration unless you move up in caliber.

-Lou