I'm not sure just what is and isn't true relating to killing power anymore. I think shot placement is the thing but when you get down to the bullet must penetrate to the vitals, well, suddenly it might be more about bullet build. In your deal from Chuck Hawks The 140gr 7mm bullet might penetrate deeper than the 150gr 30 cal bullet. But go to the 165 gr 30 cal and the story might change tdue to increased sectional density. You can juggle a lot of things around.

The thing to keep in mind is that a deer is not a thick skinned animal and a shot into the chest the kills quickly can be made with some rather small calibers. Many years ago P.O. Ackley made solid copper bullet's for 17 cal"s. I think they were 25gr. He reported they killed like lightning, all out of proportion to their size. How much killing power can a 25gr bullet have? I believe it did what it did because the bullet penetrated all out of proportion to it's size. We see now that the X type bullet's are found to be able to go down in size and still peretrate well. A 150gr x-type will out penetrate a 160 cup and core. No suprise there. The cup and core is going to shed more weight and weight penetrates. A 150gr X-type may retain 100% 0f it's weight, the cup and core may shed 30%. That means the X-type goes thru at 150gr, the cup and core at 105gr at some point. Take a 180gr cup and core and shed 30% and it falls to 126grs. Take a 126grr object and a 150gr object and drive them at the same velocity and the heavire object will penetrate deeper because of it's extra weight.

But just how much penetration is necessary on a deer size animal? I only recall recovering one bullet fron a deer in my life. There was a couple that blew up in the deer and I didn't get but mostly they shoot thru, that's all cup and core bullet's.Most people buy the premium bullet's because they believe they are getting some kind of edge. On deer size game it's very doubtful. On larger game I still doubt it but you have to re-think the bullet and the cartridge your using. If you use a cartridge with high velocity, excess of say 3100fps, and cup and core bullet, impact will play a big part it loss of bullet weight. Take the same cartridge and use a heavier bullet at say 2800fps and everything changes. Now the bullet is likely not to shed a lot of weight that will hamper it's penetration. Take a 300 mag shooting a 150gr copper bullet and let's say you retain 150gr. Now take the same 300 mag and use a 200gr bullet and you have a stouter built bullet that might retain 80% of it's weight. That will give the 200gr bullet 160gr retained weight, heavier than the 150gr copper bullet and weight equals penetration. Velocity does to but that's another story!

Now I'm sure someone else can figure something else out from this and that's because I don't think we really understand killing power. Death occur's when vital organs or the central nervious system are disrupted to some degree. simple as that. Now, just ask yourself what it takes to do that. I can drop an elk in it's tracks with a 22LR. Just depends on where you put the bullet you use. I can do the same thing a whole lot easier with a lot of cartridges from the 260 Rem and up and have a lot better choice of shots.

This was the long answer, now the shorter answer. How far removed is the 7-08 140gr from the 30-06 150gr, quite aways in my opinion. The 7-08 is fireing a heavy for calibre bullet with good sectional density. The 30-06 is fireing a more fragile bullet for caliber of lesser S.D. On a deer it won't make a lot of difference, on an elk shot thru the shoulder it just might!

Sectional density is something to consider, but it's not the whole picture.  As Don said you have to consider the bullet costruction too. 

As far as sectional density goes.  Take for example a .30-06 and a .270 Win.  Both can be loaded with 150 grain bullets.  Both weigh the same and are typically thrown at the same muzzle velocity, around 2800 ft/sec.  Let's say we use the same brand and construction of bullet for both calibers.  The .270 has a diameter of .277 inches, the .30-06 has a diameter of .308 inches.  They will both hit the same target at the same energy level delivering the same mass.  The slightly smaller diameter of the .277 bullet will allow it to penetrate better in theory, probably in actuallity too.

Something you have to get out of your head are terms like killing power, stopping power, knock down power, etc.  These terms are largely myths made up for marketing reasons meant to appeal to peoples preconceptions about bullets.  We all read about his stuff in magazines and articles, etc.  In all my years of watching lead and copper collide with flesh on biggame I've never witnessed anything that would define these terms.  Animals die when shot by bleeding out, or by destruction to the centeral nervous system.  Larger animals will have more blood in them so you need to create a hole that will create more and faster blood loss.  The larger and heavier the animal the more power you need to penetrate and reach these vital organs to kill them.  That's the reason you chose larger bullets with more velocity behind them for larger heavier animals.  The denser the target the more mass and kinetic energy you need to penetrate it.  Most people never realize that this is the real reason behind it caliber selection.  Hope this helps.

A little further on what Don said in a truer comparison you need to compare each caliber with the bullet weight best suited to it.  I personaly wouldn't use the 150 gr bullet in my -06 for big game hunting. While it will certainly work to squeeze out the best in terms of energy, trajectory, and ballistic co-efficient, I would choose the 165 or in  my case currently the 168 gr bullet for antelope and deer. A heavier bullet due to the higher BC will retain more of it's energy way a ways out there which does make a difference when shooting at game at extreme ranges. A lighter bullet will always starting shedding velocity faster and shed velocity can make a difference in 'killing power' especially at long distances.

For elk hunting most -06 users use the heavier 180 gr bullet or the 165 but you don't see many toting the light 150 gr bullet.

The 140 gr bullet is the optimum for the 7mm 08 which is a fine cartridge, but I'd argue that the 165 or 180 would be considered ideal for the -06 and you can move up to as heavy as 220 if needed in the -06.

In reaching the heaviest bullet weight for the 7mm I like the 175 gr weight but pushed by a 7mm Mag at almost 3000 fps which has a very flat trajectory and carries a lot of energy downrange. The 7mm -08 is only going to be traveling around 2600/2700 fps with this weight. The -08 is great due to it being a short action cartridge meaning a lighter rifle to tote and it's light recoil.

As has been said many different variables when it comes to the most efficient caliber for ones intended hunting and many like these three and many in between  will do just fine if you sink a bullet into the boiler room.

I know a lot of people have very strong opinions on guns, cartridges and killing power they provide. I am not a lot of people, I'm just me. I do happen to be something of a gun nut, however and own a pretty large collection of firearms. Just to set a base line here, I own at least 30 different chamberings in center-fire rifles. I have also, at this point in time, taken deer with at least 20 different chamberings if you include a muzzleloader and shotgun, no less than 18 if you feel otherwise. Simply the facts.

It's my very strong feeling that a bigger caliber bullet will always kill more efficiently than a lessor one, if correct bullets are used. Use a 30/06 with a 180gr bullet designed for use on elk of game larger than deer and perhaps, you'll encounter a problem if no resistance is encountered by the bullet as it strikes the animal.

I have killed deer with rifles in chamberings ranging from .257 Roberts to .44 mag. There is zero doubt in my mind that a .30 cal wound channel trumps a 7mm one. I did NOT say it will always kill more decisively. I am saying that with proper bullets it will do a better job on deer in like circumstances. (I am a strong believer that a deer's disposition at the time of the shot holds a great deal to do with the outcome, period). If a deer is feeding serenely and shot in the boiler room, it may well drop at the shot, whether a .243 or a 45-70.

If, however, that deer is spooked, chasing a doe high on testosterone or something similar, the same shot may well yield way different results. My experience shows me that a bigger bullet is always better (again if also a properly constructed one) and I will take 10 times out of 10 times a bigger bullet and caliber, every single time.

The caliber that strikes the biggest blow to any deer sizd animal, bar none I've used is the very fine .35 Whelen. It's a chambering that's not needed for deer, but if you want a DIT with any and every shot, the .35 is most likely to do that in my experience.

A 30/06 does not have offensive recoil to my shoulder. I know already that in my experience it kills better. It is my choice, hands down, every day of any hunting season. 

Hi Jim,

I think that you are not alone in your appreciation of the 7mm-08 cartridge.  While I don't own one, I do own three 6.5x55s which are very similar.  The difference between them in terms of therotical killing power is that the 7mm bullet has a slightly larger frontal area while the 6.5mm bullet has a slight advantage in terms of sectional density (SD).  At the end of the day, they are essentially the same.

As it has been stated for years, phot placement is the key to success and that is the only factor that in not contained in ballistic calculations and this is what makes the real difference in the field.    So, if we believe that this is true, then we must give it more value than bullet velocity, diamater or sectional density.  Maybe!

For the purpose of this post I will use the virtues of the 6.5 because I know them better than the 7mm-08 for comparison.

There are tables on websites like Chuck Hawks that list the SD of bulets and SD figures are also listed on bullet manufacturers sites as well.  But having a SD number alone means nothing unless you know what it means in the real hunting world  Beyond its construction, SD has everything to do with regards to terminal performance and that is what we are looking for...successful end game.

What these tables can do is give you an approximation of the SD that is necessary to humanely harvest any game because they corresponding directly to the game weight.  I hope that this makes sense.

So, if you think of SD as the bullets ability to penetrate, then the long slim 6.5mm bullet has an advantage over a short fat one.  That said, the 140 grain 6.5mm bullet most likely will penetrate as deeply as a 190 grain .30 caliber bullet.  This is why lighter bullets chambered in the 6.5x55 Swedish Mauser, the .260, the 7X57, and the 7mm-08 perform better than most would expect. They penetrate through and through.   

To continue, and to answer your question (kinda sorta) the 7mm-08 should at least equal or out-perform the  30-06 using the 150 grain bullet because they have an inferior SD.  The 30-06 advantage comes into place when heaver (read longer) higher SD bullets are used and these normally start in the 180 grain weigh ranges.  Heavy bullets for the caliber is where you will find those with a superior SD and this is what you need to hunt larger than deer sized animals at longer ranges like elk, moose and brown bears.

Using the SD of a bullet you can then match the the caliber to the game.  There are reports that the 6.5x55 has killed many moose in Scandinavia which are the equal to our Elk and I have seen the results of a moose that was harvested by a 7mm-08.  Personally I don't think that it is so much the caliber than the distance shot.  Most large game, as you already know, are taken within 100-150 yards and your 7mm-08 should do just fine most of the time as long as premium bullets are used.    

So, why do you like your 7mm-08?  I don't know exactly but I suppose that it has a lot to do with the game that you are hunting.  The 7mm-08 is a fine and versitle short action action that is just a fine brother in the '08 family.  There are few who can honestly say anything bad about it if used at proper game and at proper distances.  No it is not a brown bear cartridge; that is why we have 30 and much larger and more powerful cartridges for.

In closing, I must stress that one of attributes that the similar calibers that I compared to the 7mm-08 and their collective success is based on their low recoil which directly attributes to superior shot placement.  But again, you already know this.

Also, since I am addressing this subject, it just really bothers me when calibers like the 7mm-08 are referred to as entry level calibers; I don't quite get it.  What could be better than your choice of a soft recoiling and extremely effective caliber that facilitates good shot placement.

Does a bigger bullet making a bigger hole mean it's the better bullet, or more efficient killer?  I say no personally.  Efficiency is being able to do more with less!  Being able to take an elk equaly humanely with a 7mm bullet as you can with a .35 caliber bullet means that (in the definition of efficiency) the smaller 7mm is more efficient all things considered.  Consider that archery hunters take elk every year with arrows that don't leave a hole as large as a shot from a .30+ caliber bullet.  Mass will get you into the vitals, that's all you need is to be able to destroy the vitals.  A bullet with more velocity and mass will punch through tougher objects better than will a lighter bullet of the same velocity.  True that a bullet should be constructed tough enought to hold together long enough to reach the vitals.  However I don't consider a bullet that breaks apart inside an elk to always be bullet failure if the result is a dead elk that didn't go very far, and yes I've had that happen once where the bullet broke into two parts on it's way out the other side, but stopped before exiting the bull. 

Jim your 7mm-08 will work just fine as long as you do your part.  I've seen plenty of elk that have been taken with a few various cartridges from .243 Win all the way upto 300 Win Mag.  I can say that my .270 Win has never failed to reach an elks vitals with the 130 grain Grand Slams I've used.  I've been equally impressed watching bulls go down from 150 grain bullets from a .30-06.  Afterall efficiency is doing more with less right?