Home Forums Hunting & Shooting Ask The Gunwriters ST and JB, is there a formula for calculating optimum bullet weight?

260Rem--

Geez, this is getting pretty interesting. Before I start, let me say that I used to buy one magazine purely because Steve DZ was their star staff writer and I wanted to read everything he wrote. It appears he won't be anymore, and the rest of the magazine isn't worth buying for fire-starter. Well, maybe not that bad, but Steve was MY only reason to buy the darn thing.

Steve and I have talked about ballistics and killing power many times and are pretty much in agreement. I fully agree with him about .210 being an adequate sectional density for deer, given other parameters. I shot my last deer last fall with the .250 Savage and a 100-grain Speer Hot-Cor (SD .216). This was big mule deer doe, facing me at about 150 yards, the rifle a Winchester Model 70 Carbine from the 1980's with a far older Lyman All-American 2.5x with post reticle. Obviously not the scope for shooting prairie dogs at 300 yards, but it proved totally adequate for shooting a deer in the dimple at the base of the neck at 150. This is a deadly shot too, on anything, but must be hit precisely. The doe went down and never moved; the little bullet cut the windpipe and carotid, and broke the spine at the bottom of its curve into the body, scattering bone throughout the chest.

But I am not wedded to one bullet type. Since I write more generally about rifles than Steve, I try to give everything out there a fair shake, from the cheapest and most traditional (Speer Hot-Cor a good example) to the most expensive and cutting edge (Swift Scirocco, Barnes X, etc.)

This brings us back to our original question: the ideal bullet weight for a given cartridge. I don't think there is one, simply because there are so many different bullets on the market today. A Barnes X or Winchester Fail Safe or Trophy Bonded Bear Claw makes a cartridge act bigger than it would with something else, even a Nosler Partition. Many of the simpler bullets also have an ideal muzzle velocity range; push them much faster or slower and they don't behave so well.

Because I use so many different bullets I also don't believe in magic bullets. If we put any bullet of reasonable weight and design in the right place, it will kill well. I long ago lost any desire to see how small a cartridge could be used to kill deer, or anything else, mostly because there is no real bottom. Put a .22 Long Rifle in the correct spot and they're dead. I have even heard of one documented account of a woman accidentally killing a bull elephant with one .22 bullet in the chest! She was just trying to scare the darn thing out of her garden, and half an hour later heard a crash. Tembo had tipped over!

I am not so enamored of Ballistic Tips as Steve, mostly because I've had a couple of bad experiences with them. These were relatively early on in my experience, so I've been leery of them. I know Layne Simpson pretty well, and he's been a big believer in BT's for a long time (he estimates about 60 animals), but recently had his faith shaken by a 140 from a plain vanilla .280 Remington that only penetrated a couple inches into the shoulder of a Dall sheep at about 200 yards. This sort of thing can happen with Ballistic Tips, or at least most models of Ballistic Tip. Some are made with heavier jackets, such as the 120 7mm and everything above .30. These work much more reliably, at least in my experience.

I far prefer Speer Hot-Cors or Hornady Interlocks to deer-weight Ballistic Tips for the same general purposes. I did have a 105 6mm Hot-Cor come apart on the skin of a whitetail once, leaving the jacket in the entrance hole, but in larger calibers they have worked like a charm as long as I didn't push them to more than 2800 fps at the muzzle. Interlocks work fine at even higher velocities, up to 3100 fps in my experience, and are one of my favorite bullets, especially for pronghorn/deer/caribou sized game.

But a lot of the expensive spreads are very versatile. I have more experience with the Barnes X, Fail Safe and Nosler Partition than the others, but have tried just about all. In particular, the Barnes X and Partition will expand on the slightest excuse and still drive at least to the far side of the animal. Both will also do this even if heavier bones accidentally get in the way. This fall I watched the 140 Triple Shock X-Bullet in action on both a coyote and an elk, driven from a .270 Winchester (Ultra Light Arms) at 3000 fps. The darn bullet blew an ENTRANCE hole the size of my fist on the coyote--yet also broke both shoulders of a medium sized bull elk. Range in each case was about 200 yards. Now that's versatility!

What I'm getting at here is that there are many ways to accomplish the same thing. I do require a bullet to penetrate far enough to do its job, and don't mind if it goes on out the other side. But as noted before, I don't believe in magic bullets. I've seen pronghorns and small deer with their heart and lungs shredded by quick-expanders started at 3300+ fps walk off as if unhurt, falling after 50 yards or more. I have seen supposedly super-hard bullets drop them in their tracks with rib shots. I've also seen the opposite effect from both types of bullets, and everything in between.

I've also seen bullets fail to break the neck-bone of two big deer and one elk, despite very precise shooting. The animals fell, but two required a second shot when they started to get up, and the third (a 6-point elk) luckily also suffered a slightly nicked jugular, and died a half-mile later. All three bullets were found, widely expanded, lying against the vertebrae. Incidents like these have made me lean a little more toward the tougher bullets.

The original question, of course, was more specific, about my use of 115-grain Nosler Partitions in the .250 Savage, and if some other bullet weight might be more ideal--and if there were formula to arrive there. Obviously, I have used other bullets in the .250, but the 115 Partition, despite its muzzle velocity of "only" 2700-2800 fps, very quickly dropped everything shot with it, and not with head or neck shots, but chest hits. The game ranged from coyotes to elk. Because of the longer bullet, in practical terms it shoots just about as flat as 100-grain bullets, at least as far as most of use can precisely hit with a .250 Savage.

Is it ideal? As noted above, there are a great many ways to get from here to there. They all start with learning to shoot, and learning to hunt well enough so that the shot is certain. Once we get there the bullet doesn't make nearly as much difference--but trying to make up for lack of shooting skill or hunting with a bigger rifle and heavier bullets is a losing cause. This is a universal pet peeve among big game guides the world over.

As with Steve's, my experience is that anybody who can shoot a .270/7x57/.280/.308/.30-06 or anything in that general range has plenty of gun for any non-dangerous game on earth, and anybody who can shoot one of the smaller .25's has plenty for deer-sized game. The bullet only matters if it doesn't get inside. My own formula is: 2 lungs=dead+.

JB

Jeff,

To answer your original question about formulas for optimization of bullet weight: there isn't one.

And for rules of thumb, there are lots of them, but you have to understand the "zone of convergence" -- if you will permit me -- in which the rule describes reality more or less accurately. For most of my shooting, the SD rule of thumb is .300, and the application is dangerous game in Africa with rifles of .375" caliber and up.

By the way even the Greenhill formula needs fixing in the 21st Century; it works with old style jacketed lead bullets, but you need to adjust the constant in the numerator upward with modern bulleys.

Back about (mumble) years when I was a recent graduate in physics and in my velocity stage, I used to think that i could derive things such as measures of effectiveness for cartridges. I did a lot of computing, graphing and figuring. It did keep me off the streets and out of the bars, but it was going hunting and shooting animals that did the actual optimization work.

By the way we are dealing with a collection of parameters that generally are monotonic: there don't happen to be any local maxima or minima where a wild optimum might lurk awaiting capture. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Mostly today I just take a .308 Win or a .375" with whatever bullets I am interested in writing about and get amongst 'em.

I definitely enjoy reading what DZ and JB have to say about their field results. The results in this thread in particular are very useful.

jim dodd

Excellent reply. I hope everyone appreciates that Mule Deer just gave us a FREE ARTICLE! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Point of curiousity for MD and DZ -- I may have missed this in a previous discussion but why'd Nosler go with the thicker-than-usual jacket on the 7mm/120 BT? Is it thicker than the jackets on their heavier 7mms?

For my own totally unscientific theory, I look at tables and look first at the heaviest bullet weight that doesn't fall off a lot from 200 to 300 yds. with a 200-yd. zero and/or is especially "velocity-friendly." For the cartridges I load this is generally the 2nd or 3rd heaviest weight. E.g. the .30-06/180 doesn't drop much more than the 165 and a lot less than the 220, the .300 Savage/165 can start almost as fast as the 150 and a lot faster than a 180.

Of course appropriate construction is important and I'll readily shift up or down a notch if a person with some experience recommends a particular bullet for my purposes, or if it shoots better. E.g. the 200 Partition that shoots best in one of my .30-06s or the 139 Hornady in my .280.

John

I think that this is a good subject. Imagine the delimma of bullet makers have, to build a bullet that will expand every time, never blow up on impac, and do these things over such a wide fps range. From my own personal hunting experience, which an't as much as a lot of you, I have found exactly what one other guy said about a .240 s/d working so well. I have used a 257R for years, and killed the first few deer with 100 gr bullets. I did not like the appearance of the boiler room when hit there with them. When I started using the 117's, the same shots looked almost like what I was used to seeing from my 270. I think that the higher s/d will give good performance in a wider range of vel's. Being there is plenty of material to keep it from comming apart at close range/high vel, yet still can be made soft enough to be dependable at the long range/low vel's. When I think of bullets with known sucesses in the hunting field, I find that they all share that .240+ s/d. I also think that we are leaning more toward being game assassins, rather than hunters. Makes me wonder if we would use "smart bullets", should they come available. dingus

Mule Deer,
Thank you for taking the time to write such a well thought out post. I always enjoy your writing, and most every piece I read reinforces my belief that you're a man who knows his stuff.

Mule Deer Writes:

"trying to make up for lack of shooting skill or hunting with a bigger rifle and heavier bullets is a losing cause."

Truer words have never been spoken.

BMT