Ok in the following scenario the game is grizzly bear and the rifle is a .338 Winny. If you take two bullets of different weights loaded to the same velocity, say a 250 grainer and a 175 at 2600 fps. And the 250 will have retained say 70% of its original mass, putting it at 175 grains, when the bear is shot and the bullet finished penetrating. Does that make a 175 gr. bullet that retains 100% of its weight ok to use one griz? I used this combo because normally a 250 is considered about right and a 175 to light for bear. However, the frontal impact area is the same as is the velocity and it ends up the same anyway. Also the shots are identical. What do you think?

Assuming proper construction, the 250gr. bullet would have penetrated more deeply, causing more damage.

George

Bullet construction is far more important than bullet weight where penetration is concerned.A 180gr failsafe or barnes-x could easily out penetrate a conventional 250 gr bullet and would be a better choice where penetration is desired.

The sectional density of the 250 grainer is around .313, much higher than the 175 grainer. If the two bullets are similarly constructed, the one with the greater SD will outpenetrate the other.

The lighter one will travel faster, but it will expand at a faster rate than the slower and heavier one. There too, the 250 grainer will outpenetrate the 175 grainer.

Talking about bears: Have you ever used .338 275-grain Swift A-Frame bullets?

Also, the larger bullet will have more energy than the lighter bullet when pushed at the same velocity. As it sheds some of its mass and expands, it will deposit more of this energy into the animal, causing more damage.

Well, you have been givin a number of answers.

Some of them more correct than others.

First: heavier bullets have more energy? No. For example, the 175 gr. bullet from the 338Win has only 26 foot/lbs of energy less than the 250 gr. bullet (Barnes #2). So much for that argument.

Second, the heavier projectile will penetrate deeper. Maybe. Chances are, the petals will shear from the 175 X, which will reduce the frontal area, and allow the lighter bullet to penetrate deeper than it otherwise would have.

Three, the bullet with the heavier SD will out-penetrate the other. That's applying cup-bullet wisdom to copper bullets. This conventional wisdom is only true if velocities are the same, or if bullets are of light construction.

If we go by the Gary Sciuzietti Study in Handloader of June '98, we see that an X bullet essentially has the same depth of penetration throughout it's range of designed impact velocities. That is, it will penetrate "X" inches, no matter if it impacts at 2000 fps or 3000 fps.

The primary characteristic of the light bullet is that it would have a larger cavitation effect directy after impact (due to increased velocity creating a higher pressure in the tissue) than the slower, heavier bullet. Of course, the lighter bullet would slow down faster than the heavy bullet. To put it another way, the wound channel of the light bullet would be more "pear shaped" than the heavier bullet, which would be more "cylinder shaped".

I would expect the penetration to be similar. Unfortunately, my personal experience with the X-bullets of different weight is limited to 4 animals, so I must plead "insufficient data" on that. JMO, Dutch.

Ray,
No I never have used the 275 Swift A-Frame in a .338 or any rifle for that matter but would like to in the future.

Wound channel! Thats the difference. An X will make a narrower wound channel than a heavier more conventional type bullet so the actual tissue damage even if it penetrates more, could be LESS.

Also the 250 grainer may TERMINATE at 70% of its weight but isnt it the trip it takes while it is leaving some of those pieces in the bear that counts? In other words the 250 will have a better initial "punch" through the tough hide and then should do at least as much damage to boot.

o.k. my 2 cents worth,what bullet weight can YOU shoot the best,if the heavies cause you to flinch,I`d go with the lighter one(but only a super premium)shoot them with what you can shoot best and knock em dead.j.m.h.o.