Effect of bullet diameter (caliber) on terminal performance.

[grit]

Often, while reading about somebodies new big bore, I find myself thinking, "I could do the same thing with my... much smaller whatever".

It is very possible to shoot the same weight and type bullet across several calibers, even from the same case, same velocity. For example a 180 in a 7, 30, and 325 WSM. I'm well aware of the BC differences, this isn't my question.

Assuming same bullet weight, construction, and impact velocity, what effect does the larger diameter have on terminal performance? Presumably the smaller diameter has greater penetration, while the larger diameter creates a wider wound channel....mabey. I realize there are no degrees of dead, and the discussion is purely academic. Still, I'm interested.

Many of the big bore calibers seem to operate precisely this way. Shooting the same weight bullets as smaller diameter counterparts. The fans of these cartridges all claim impressive terminal performance.

I regularly shoot small calibers for the application, as well as arrows and handguns with large diameters and low velocity / energy levels. My only negative experiences have been due to my shooting, as far as I can tell.

 

[Long Time Long Ranger]

They have caliber minimums in Africa for a reason on dangerous game. Larger calibers kill exponentially better on large and tough big game. A small caliber can kill stuff but a large caliber can do it better. I see numerous elk lost each year to 7mm's that would have been found if hit with a 338. Greenhorns have a problem with that. They know joe blow who has killed twenty elk in thirty years with his 7mm and is a top elk hunter. Many of us here see that many per year with groups of cow tags etc.

I can relay numerous stories but a good one two years ago was a guy shot a nice B&C bull with his 7mm remington three times and knew he wouldn't go far. As he followed up the ridge where the elk went for about a half mile he heard a loud shot above him. He walked up to the B&C bull and got mad because another hunter with a 338 had put his elk down and claimed it. The 338 guy said he didn't look hurt to me and rightfully claimed the bull. If the 7mm guy had a 338 he would have a B&C bull but he didn't so he was mad the other guy did. Not saying a small caliber will not kill stuff but a large caliber will do it much better on large big game like elk.

 

[Outlaw6.0]

My (limited) understanding of caliber size & it's effect on terminal performance is this: The larger the diameter of the bullet, the larger the cross sectional area of the projectile (obviously). The larger the cross sectional area the more shock/trauma exerted upon impact, at least in theory.
It reminds me of the old buffalo hunters & their rifles... Them ol' boolets didn't go very fast, but they sure could lay the smack down...

 

[Browninglover1]

I've often wondered the same thing, and would love to have the money and time to test out the theory shooting cow elk with 180 grain bullets from a 7 wsm, 300 wsm, and a 325 wsm. I would expect you'd have to shoot upwards of 10 animals with each caliber from similar distances and angles before you could even start to form any conclusions. If anyone has the money, I'd be more than happy to do the testing

 

[Broz]

Myself like several others on this forum see a dozen or more Elk taken each year. I am of the belief that the bigger the bullet the better, no matter which way you measure it.

Jeff

 

[grit]

Sure, bigger is more effective when comparing a 180 out of a 7mm vs a 300 out of a 338.

My question is more specific. Given the same bullet weight, construction, and impact velocity. Is there any real difference in terminal performance between calibers?

 

[Broz]

Sure, bigger is more effective when comparing a 180 out of a 7mm vs a 300 out of a 338.

My question is more specific. Given the same bullet weight, construction, and impact velocity. Is there any real difference in terminal performance between calibers?

I see what you are saying here. Like a 230 gr from a 300 rum compared to a 230 gr from a 340 Wby? Both at 2900 fps and of the same bullet construction? Then I would have to say it will at this time depend on shot distance. Out to 6 or 700 probably not alot of difference. But as you get farther then you have to enter BC and retained velocity into the equation.

Jeff

 

[Long Time Long Ranger]

I see what you mean now also. This may add some to that. Many bullet manufactures use a thinner jacket and softer lead in light for caliber bullets and tougher with the heavies. So that would make a difference. So many factors. I can use my 22's through 257's and drop deer like lightning with lung shots and explosive bullets at 3600-4200 fps. Where my 338-378 wby with a 225 CE would send that deer into high gear for a hundred yards before it went down. So it depends on the animal, bullet construction and velocity. But once you get into the large big game animals like large bull elk and not cows the parameters change and large calibers have more effect on game to carry you to longer distances.

 

[angus-5024]

If you had a very dense medium that would stop both bullets, I would say that it would be pretty equall. But if the medium wasnt so dense (ie. deer) and there was complete pass through on both bullets, I would think that the larger diameter bullet would have more suface area to dump that energy/momentum. But thats speaking purely energy/momentum, if you were to talk penetration (ie. elephant staight on heart shot) the smaller bullet would probably penetrate deeper, more likely reaching vitals. That being said I would never shoot an elephant in the heart... or use a little gun.

Im completey talking out of concept and the only physics knowledge I have comes from high school. Just the way i think of it I guess.

 

[grit]

If you had a very dense medium that would stop both bullets, I would say that it would be pretty equall. But if the medium wasnt so dense (ie. deer) and there was complete pass through on both bullets, I would think that the larger diameter bullet would have more suface area to dump that energy/momentum. But thats speaking purely energy/momentum, if you were to talk penetration (ie. elephant staight on heart shot) the smaller bullet would probably penetrate deeper, more likely reaching vitals. That being said I would never shoot an elephant in the heart... or use a little gun.

Im completey talking out of concept and the only physics knowledge I have comes from high school. Just the way i think of it I guess.

Speaking of elepahants and small bullet penetration, "Karamojo Bell", a famous elephant hunter reportedly killed some 1000+ elephants. He killed 80% or so with the 275 Rigby (7x57 mauser), and the balance with a mix of the .256, 303, and 318. He preferred the brain shot, but took heart shots when required. Critical factors were solid bullets and precise shot placement.

 

[dig]

Elephants can be different story, and the reason Bell used a small caliber is because of his violent experience with large bores (8 bore black powder) and cost factors as was a market Hunter (hunted for profit).

While I am no expert but have killed and seen Elephant killed penetration for a brain shot can work and calibers like the .375 H&H with solids tend to penetrate as well or better than the large doubles say 470 NE. However, the big bores are much better for heart shots and/or shoulders to break them down and of course charges with more margin for error.

As LTLR stated there are minimum caliber and/or enery requirements in most African countries for "dangerous game" for a reason. Today we are sport hunting and not market hunting. I am sure you could kill lion with a 22 mag with proper shot placement but NO I would not try it.

On smaller game I totally agree that the "energy dump" with thin jacketed, small, fast moving bullets tends to take deer sized animals much better. Thousands of antelope are cropped on South African game ranches every year with efficient cartridges like the .243 Win. Personal experience shows that my 25 caliber works much better on small course deer than my fast 30 cals. The 30's tend to pass through, they do the job but 25's dump the animal with proper placement. Again, distance is an issue with the 25 vs the 30.

Bigger game absolutely diameter matters and leave a much better margin for error.

Bottom line its all a trade off and as stated it depends on the distance you intend to shoot and of course size of animal.

 

[royinidaho]

Interesting discussion.

What if a 130 grain bullet of similar construction were fired at similar velocities from 25/6mm/7mm/30/8mm cartridges into gel or other terminal performance material? It would seem to me that the larger the caliber the more violent the results and possibly less penetration due to larger frontal expansion. Dunno though.....

 

[grit]

Interesting discussion.

What if a 130 grain bullet of similar construction were fired at similar velocities from 25/6mm/7mm/30/8mm cartridges into gel or other terminal performance material? It would seem to me that the larger the caliber the more violent the results and possibly less penetration due to larger frontal expansion. Dunno though.....

No doubt ballistic gellatin would clearly illustrate the differences. It'd be fun to obtain some and do all kinds of testing. I'd like to test several bullets at extreme ends of the velocity spectrum. Too bad pigs aren't transparent.

 

[Nomad]

One man with one gun say an 06 will do a great job shooting a 30 cal bullet at proper
distance.
Shot placement is the major factor there is no perfect bullet out there the Accubond and PT
are two very good bullets and the PT has killed thousands of elk and deer with the 06.