^^^^^^
Yes another point to think about. If we look at any bullet I know of that doesn't shed it's jacket, the best I have seen in expansion compared to original diameter is about 2X. In other words the very best 25s will be about 50 cal when they stop, the very best 30 cals will be about 60 cal ----- and so on.
If we look at 60% retention of a 30 cal 150 grain we see a retained weight of 75 grains and at best a diameter of about 60 cal. Such performance will be deadly in the right place, but seldom will exit game. that's why I like heavier bullets then 150 grain for elk. It's also why I was so surprised and pleased with the number of exits I got a few years ago from the Winchester 150 grain power Points on elk. I recovered 2, and those weighed 129 and131 grains. It would have been "better" if I had recovered none, but I also would not have learned how well those bullets worked. I am betting that if I'd been using 180 grain power Points I would not have recovered any.
now the idea that some bullets will open up to a larger diameter than others is absolutely true, but I know of none that average more then 2X original diameter and don't loose more then 40% weight. So the theory you examine is valid and worth study, but I don't see any real-world application of it with frontal resistance being over 2X original diameter. I would not be dogmatic and say that are none, but so far in about 50 years of doing this, I have not personally seen one yet.
bullet that opens up to about 30% over original diameter and still holds together is a very good bullet for elk in most cases. To illustrate, I look at the Swift A-frame 180 grain shot from a 30-06. The nose will mushroom out to about 45 cal and you don't recover many from game. Shot into out test trough we see excellent penetration and bone breaking ability, but a narrower wound channel they you might get with a "softer" bullet. But the wound channel is larger enough in diameter to kill quickly and the fact that penetration is 100% means that you actually get more blood loss then you would from a large but shallow wound as you may see with a Sierra Game King. So matching the bullet to that size of the game is important in marge animals but less so in small er animals. A 3/4" diameter wound clear through a whitetail will kill it fine, but the deer often will run a short distance farther than if you had a 2" wound 75% of the way through that same whitetail. BUT the large diameter wound from a bullet that comes apart is sometimes a wound that veers off and can be gory but not hit the organs you want it to hit. Not often, but it does happen.
My outlook on these thing is pretty simple. Unless I am wanting to test a bullet (like I did 2 seasons ago with the 8mm 170 gr SSTs) I fall back on what I know. That is simply that a 100% penetration with 30% expansion is always good. A 50% penetration with explosive expansion can fail, sometimes dramatically. So if I am in a place to choose, I take narrower wounds that got through in a fairly straight line over the possibility of bullet failure.
In Africa the largest of game is often shot with non-expanding bullets. Why? Because for many years many if not most expanding bullets would break up on Buffalo, Hippos Elephant Rinos and sometimes even loins. Solids didn't. Now days I recommend expanding bullets even for the largest game in Africa, but that's because the bullets we have today beat the pants off what we had only 40 years ago. The idea that a bullet that will kill a hippo is not good enough to kill a deer seems a bit simple minded to me. There are better deer bullets. I don't deny that! But the solids would kill deer just fine too. A bullet that goes from say a 264" to a 35 cal on a deer and hold 60% or more of it's weight is going to kill any deer you shoot with it and do it well. (Baring the times you gut shoot them. A gut shot deer hit with a 12 gauge slug can run a long ways, as many here will attest)
My Garndsons and my Daughter have all killed elk with a 257 Roberts using Nosler and Barnes bullets and all have been good kills with exits. Those kills were not as dramatic as some I have made with larger rifles, but none of their bulls or cows ran more than about 30 yards after the hits.
I have many bad memories of tracking down bulls hit with 300 mags and 7Mm mags that were shot poorly, and also about 15 that were shot in the right place, but with bullets that failed. The 300s and the 7 Mags are GREAT elk guns, but no gun or cartridge is as good as it could be if the bullet you shoot breaks up. I hear that "bullet ___" did fine for me" all the time. I believe them too. But those that tell me that often have not hjunted elk for 50 years and seen more then they can count killed. I have. I see a pattern and I am relating what I have learned to all who want to learn from my experience. "my ___ bullet was fine" is true many times, but I can say that the best bullets for the job are fine too, and I have not seen a pattern of failure with them. So if you have a 90% chance of satisfaction with bullet X and a 99.99% chance of satisfaction with bullet Y, it just makes sense to choose bullet Y. Until you have killed many dozens of elk the statistical eventuality of what works and doesn't work is not learned --------------------------------- unless you learn from the mistakes of others.
I offer my experience to all who want to know. Free of charge too. (I already paid for the knowledge) Those that want to learn from their own experience are well within their right to do so. But I have seen mistakes made and made more then my share too, so I can tell you that I think "bullets Y" are Nosler Partitions, Barnes X, Swift A Frames, About anything bonded, from any maker, and in cup and core bullets the ones I have seen that work very well have been 120 grain Remington 257 cal power points, 150 grain 270 cal Remington Power Points, Hornady 160 grain 6.5MM round noses, 175 grain Hornady 7MM Spire points, 220 grain round nose 30 cals from both Hornady and Sierra, 30 caliber Winchester Power Points in 150 and 180 both, and the Remington 180 grain Core-Lokts made in the 70s (newer ones seem to be made with lighter jackets) and 375" 270 grain Winchester Power Points are some of the best performing bullet I ever used in my 375H&H. Now my recommendation here are shallow because of the exact detail Starman brings up. What was working so well for me may not be the best for you if you shoot a faster cartridge than I did. What works to perfection at 2500 FPS may be a total failure at 3200 FPS.
So I almost always come back to the foundations. Nosler partitions Barnes X, Swift A-Frame and if you don't use these test to see if your bullet will hold 60% of it's weight. If it does you are likely to be fine
