Answers to Posimag
by Patrick Smith

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The following is in response to a pregnant paragraph from good pal and customer "Posimag", as posted on our message board 6-1-00. My response grew so large it warrants putting it here on the Forum instead of on the message board. Iíll break down the questions/points Posimag listed and try to give what insight I can, issue by issue:

  1. "In the 308 case which of the neck sizes are flatter shooting?"

OK, here are the drop specs from the latest Speer manual. All are based on a 300 yard zero ( see below for a discussion on why ) with the "all around" bullets for the given caliber. The velocities are about what you can expect from a carbine length barrel.

  1. 243-- 100gr. bullet with BC of 400 and muz. vel. of 2850: 100yds.= 4.4"; 200yds.=5.3"; 300yds.= 0; 400yds=--12.5".
  2. 260-- 140gr .bullet with BC of 490 and muz. vel. of 2700: 100yds.= 4.8"; 200yds.= 5.5"; 300yds.= 0; 400yds= --12.9".
  3. 7/08-- 140gr. bullet with BC of 434 and muz. vel. of 2700: 100 yds.= 5.0"; 200yds.= 5.8"; 300yds.= 0; 400yds.= --13.7".
  4. 308-- 165gr. bullet with BC of 410 and muz. vel. of 2700: 100 yds.= 5.0"; 200yds.= 5.9"; 300yds.= 0; 400yds.=--14".
  5. 358-- 225gr. bullet with BC of 430 and muz. vel. of 2500: 100yds.= 6.0"; 200yds.= 6.9"; 300yds.= 0; 400yds= --16.3".

Youíll notice that the drops arenít all that different! By using a 300yd. zero youíve created a pretty useful window of drops. Itís easy to judge distances when theyíre fairly close and you can hold UNDER out to around 250yds. more reliably than holding OVER way out there. These slightly higher than traditional hundred yard site-ins also allow my small game handloads to be right on at 25 yds. (see the Loading Big Game Rifles essay here on the Forum to read about this useful practice). Note too that these drops are from a manual thatís using sea level as the basis. My normal long range shooting spot is at 9500 feet and I get drops some inches less than whatís indicated here.

Letís talk about that. First, I urge readers to actually shoot their own guns at these yardages rather than rely on published drop tables, even if you know the velocity of your load, etc. And for you guys who are coming out west to hunt from lower elevations I suggest you shoot a round at a target at long range when you get to the elevation youíre going to hunt. If you think you might shoot long itíll be worth it to see where youíre actually hitting. Itíll be higher than it is at home.

Let me give you an example: I actually site my 308 in at 6 inches at 100yds. rather than the 5 inches given above. It only drops 7 inches at 400 yds! Take out 4 of those inches due to the 1 inch higher site-in at 100 and it still drops 3 inches less than the sea level figures indicate. The little 260 barrel on my Rambling Rifle, also sited in 6 inches high at 100 yds., only drops the 140 Partition 2 inches at 400 yds.!! Thatís because of the phenomenal BC of 490 on that javelin-like bullet. ( It was a 2" group too!) In any event itís a good idea to actually shoot at long range on location, if you can.

There are additional benefits to a high site-in (beyond the small game compatibility so dear to my personal year-round shooting style). One big one is you shouldnít have to hold over on long shots. Holding on "fur" is a lot better than holding on "air". The "brisket depth" (which you should know) is right there under your cross wires, making your reference point vivid. The "yardstick" is much easier to read accurately. Holding on fur instead of air will simply give you better results, especially if you havenít used a range finderóeither because you donít have time (rare at long range) or because you donít have one (yet).

So I hold low from about 85 yards out to about 250. That covers anything in between, of course, and since this encompasses the vast majority of shots at game it is second nature to me. For longer shots, the little warning goes off in my head and I start to raise the crosswires accordingly. Yeah, itís a heretical way to shoot, I know. I remember hunting wild boar out in California with Craig Boddington and Kyler Haman. They had already heard of my weird site-in methods. When we checked our zeros at Kylerís site-in range we had a choiceópie plate or little 2 inch square metal gong-like thing. Both Craig and I chose the little metal gong of course and both of us dinged it soundly. Kyler asked me how I held to hit it. "Six inches below its middle", I replied. I remember Kyler and Craig seemed to exchange that certain kind of glance. Next day, as we moseyed out to where we thought the pigs might be, I asked both fellows about the brisket depth of the representable boars in the area. They agreed on 15 inches. Eventually we managed to roust a good size Russian-looking beauty and he trotted across the flank of the hill across from us at about 225 yards. I happened to be in the best shooting position and so sat down, swung the crosshairs of my old 350 Remington Magnum with the bottom of his chest and let fly a 180gr. Barnes. Drilled him dead center right behind the shoulder and we had us a fine black specimen. It all happened as fast as I can tell it. My companions donít hold any more reservations about the high site-in technique. It works close, it works medium and it especially works out far.

OK, Posimag, above are as good as any (better than most) "drops" for the 308 based cartridges you asked about. Pick your poison. For elk, though, I suggest you start with the 260 or larger and leave the 243 for the deer fields.

  1. "Is the 308 bore the best for the case or can it do just as good a job in a 284 (7mm) bore but without as much foot pounds of energy?" (I did a little paraphrasing there for clarity, sorry.)
  2. Well, I think that for non-dangerous game the fact that you lose some "foot pounds of energy" by dropping to 7/08 or any other 284 bore caliber as compared to 30 caliber doesnít mean a whole lot. I refer you to the essay on "Cartridge Power" here on the Forum for a pretty thorough take on the whole topic. As I concluded there, shot placement is far more important than this foot-pounds or pounds-foot or TKO kind of stuff, even though we love to theorize about it. Nevertheless, I like 30 caliber better than 7mm myself ( I donít blame your friend for abandoning his 7 Mag. in favor of his Ď06óI chose my 308 over the Sevens too). But its not because of foot-pounds. I like the 30 better because the typical bullets are simply biggeróweightier AND bigger in diameter across the front. They make a bigger hole. I also love the 6.5ís. ( and especially the new 260 Rem. with its very low recoil). They stand out not because of diameter but because of outstanding sectional density. They penetrate like crazy! So I sort of "bracket" the sevens and choose 264 cal. and 308 cal. for different but superior virtues. To me, they both outshine the sevens. Give me a 260 Rem., a 308 Win. and a 358 Win. and Iíll hunt happy the rest of my days. I know full well that many, many men are completely happy with 284 bore rifles and get fine results but, hey, we all have preferences and thereís my defense of mine.

    I canít resist a few more words on the foot pounds thing. I thought Iíd exhausted myself on the subject when I wrote the Cartridge Power piece but noooooo, I find thereís always room for more within me when it comes to this one. No real evidence exists that foot pounds (or any of the other sorts of formulas) as a reliable scale of killing power is worth more than campfire entertainment. Jack used skinny bullets, Elmer used fat ones, and they both knocked down a whole bunch of game. They could shoot straight is all we need to know. Some say speed matters but equal numbers take big game with slow calibersóand without bloodshot meat! Everybody DOES agree that penetration is important. A bullet with a sectional density of about 250 or above will do it. You can even go below that with a premium bullet; they are all designed for great penetration. I believe the big calibersó338 and up are for dangerous game and far too many hunters who havenít learned to master their recoil are missing standard game, or wounding it. John Barsness has an excellent article in this monthís issue of Rifle Magazine on this subject entitled Kick and Killing Power. Now, John is a genuine Hunter, not just a spinner of gun mag. articles, so listen up. Here are a few quotes: "A .300 Winchester Magnum kicks twice as hard as the little .308 WCF but only adds 10 percent more velocity, and a .308 loaded with the right 165-grain bullet will take any nondangerous game in the world, even moose and elandÖ. So as Iíve grown older and bullets grown better, efficient little cartridges seem more attractive. The best are the those with the smallest powder capacity when compared to their boreÖ. In some circles it isnít fashionable to shoot such mild cartridges, but anybody who tells you they donít work has been reading too many comic books, or possibly another magazine." Talking about modern premium bullets, John also says, "What this means is that we now have such fine bullets, both in handloads and factory loads, that light-kicking calibers will provide all-around big game performance"

    Bless his heart, John Barsness tells it like it really is! Let me use my 260 Rem. to illustrate a truism. By the way, I read about this truth in another mag. recently. (Maybe all this verification of my views in the last few days is whatís got me on a roll again.) I canít find the magazine but will proceed anyway; maybe somebody will email with the details. The article was a review of the new Marlin 450 caliber. The reviewer shot for penetration at various velocitiesó1700fps, 1925fps and 2300fps. Guess which speed penetrated the LEAST. You got itó2300fps. The MOST? 1925fps. So, to bring my little 260 into the picture, 1925fps is the speed a 140gr. bullet launched from its muzzle at 2700fps. is traveling at 500yds. So letís examine the truth about killing power by taking up the results of that bullet connecting with the shoulder of an elk right there at 500 big ones. First off, the bullet will NOT open instantlyóthere wonít be an entry wound the size of the exit wound. Instead, the bullet will enter and then open up. And it will proceed to plow a very, very long swath of destruction through the interior of that unfortunate elkís clockwork. Most likely the bullet will completely exit. And the elk will go down! No elk/sheep/moose/deer on earth can withstand the lethality of this kind of PENETRATION. There will be no bloodshot meat. The fact that the foot-pounds of "energy" was just a bit over 1000 instead of the 2000 we lately think is the "minimum" for elk will make no difference. It will make no difference that I carried a 41/2 lb. rifle up to this rendezvous. That I didnít need, or use, a muzzle brake. That I didnít launch the bullet at 3500fps. (point is; itís better that I didnít). That "hydrostatic shock" played no part in this drama. The results are still thereóa clean kill.

    Iíll try to put what appears to our statistics-soaked imaginations regarding the "power", or apparent lack of it, of this shot into perspective by inviting you to visualize walking up to that elk and poking him in the shoulder with a 44 Magnum handgun and pulling the trigger. Think heíll go down? The little 260 has even more of it, theoretical "power" that is, at 500 yards than the 44 Mag. at point blank range. We riflemen ought to think about this when we think about the reality of killing power. Virtually ALL big game rifle calibers have more than enough power for any of the non-dangerous game we hunt. Period. I still wouldnít choose, Posimag, a 243 for elk and mooseónot enough bullet. Gotta draw the line somewhere. For absolute sure, though, all the rest of the 308 based cartridges will do a great job! And youíll shoot straighter.

    How about we look at this "power" thing in this light: if you can fire it from your shoulder how "smashing" can a given cartridgesí "power" really be? Weíre launching a projectile that weighs less than an ounce at a critter than weighs hundreds of pounds! Big game isnít "knocked off its feet", ever. Instead, its internal nerves, blood pressure and/or air supply is disrupted to the extent that the animal canít stay on its feet. This can happen very quickly, especially if nerve damage is massiveósuch as with a hit to the spine. The more penetration you have, which is enhanced by modest velocity, the more disruption you cause. I would be much more secure in launching a slower bullet with high sectional density into the chest of a charging bear than in launching a high velocity number, even with the same sectional density, into him. I want the bullet to penetrate clear back thru the liver, which is a blood-rich organ that, when it has a nice hole in it, brings down the animal just about as fast as a heart shot, in case I miss the heart with the shot. ( In fact, when it comes to bears, I want that blessed bullet to keep on plowing till it exits his rear end, causing as much "owie" as possible all the way!!! But thatís another story.)

    OK, one more soap box stand and weíll move on. This, too, comes from the reading Iíve done in the last few days. Good old Wayne Van Zwollóanother real hunter. In this issue of Bugle he takes on the giant scope craze. It seems Wayne and I agree that a 2x7 compact is the premier scope for any real hunter!! The rest of the monsters are hopeless dross, dragging a walking man down and contributing nothing of real worth in return. Maybe all those guys sporting these behemoths are riding around on putt-putts. I hope so. No! I really would like to see them with an appropriately svelte real hunting set-up. No again! I think Iím happier that they are down there putzing around on their wheeled steeds and leaving the backcountry to me. I can deal with it just fine by myself. Besides, they drive the game my way.

  3. "Whatís the deal on case size/shape relative to bore diameter?" ( Posimag-- I did a lot of editing here to get to the heart of your question quickly, sorry again.)

Speaking to your hunch as to why the 7 Mags. you guys were shooting were getting slower-than-published velocities, yes, the 7 mag. could be considered "over bore capacity". Overbore means the amount of powder the case will hold, relative to the diameter of the bullet itís designed to launch, is on the high side. The 308 is reputed to be sort of the ideal caseóit produces very good velocity with very little powder. It does this in all its various neck sizes too. The 30-06 is not nearly as efficient but is still not thought to be overbore. The seven mag. was originally thought to be overbore, but I gotta tell you that itís so far down the line now, when you consider the coke-bottle size 30-378, that itís not even a talked- about issue on the poor old seven anymore. My hunch is your friends just have "slow" sevens. But, Iíve read plainly in the Speer manual that they often donít get the speeds in their testing facilities that others claim for the round. Iíve never heard anybody claim that the SHAPE of the seven mm case might be the reason for some of them being "slow". At least not that I can remember. A LOT of talk goes around on case shape, though, and has for a long time. Thereís the "sharp shoulder" school, popularized by P.O.Ackley back in the fifties, that claimed that a 40 degree shoulder on a case enhanced its combustion. Iím not sure about that, but itís certain Ackley had a big impact on wildcat cartridgesóthey WILL hold more powder, thus higher velocities are achieved; so- and -so "Ackley" wildcat cartridges are common to this day.

Another school says that short fat cases give better combustion, and especially better accuracy. These folks are probably right. All of the Bench Rest cartridges are indeed short, and these cats wouldnít be shooting these cases if they didnít work.

All of this is a bit academic for hunting needs. I have a long, skinny cased 375 that shoots up a storm, as far as hunting accuracy is concerned. And I have a short, fat cased 350 Rem. Mag. that also shoots up a storm.

"Overbore" cartridges are all over the shooting scene nowadays. Some shoot very well and very fastówhich is why I canít say your 7 mags are faulty from the design standpoint. Some BARRELS are "slow", for example, and that may be whatís going on here.

I ought to cover Expansion Ratio in this context. Itís the thing that makes a case Overbore or Just Right. The 338 case, with its 338 diameter bullet installed is NOT overbore; neck that case down and stick a 284 diameter bullet in it and it IS overbore. The gases from all that powder canít get out of the 284 hole down the barrel, when the round is fired, as well as they can if they had a 338 hole to race down. Things get a bit constricted. And hotóoverbore cartridges burn out rifling faster than non-overbore ones. Still, some folks will burn a hatful of extra powder to get a few feet per second more velocity out of a given round and so bigger and bigger cases are being stuck behind bullets. Itís by no means a new thing, itís just really getting crazy, and frankly almost mainstream at this point. Same thing with ever-bigger scopes. Same with yearly "advances" in camouflage patterns (if you donít have the competing companiesí latest development every critter in the woods will immediately spot you and sound the alarm!) All this hype is eaten up by the novices, and they buy a lot of the equipment thatís sold. Bigger and faster= better. And so on.

The last thing I can say about expansion ratio is that, given bullets of the same weight, the bigger bore will allow its bullet to be launched at more velocity. Thus I can shoot a 180 grain 358 bullet faster than I can shoot even a 165 in 308 (2850fps vs 2700fps). It doesnít stay faster, of course, as the 358 round has a lower BC and slows down faster than the 308 slug.

Well, Posimag, we may be done. I think Iíve given my responses to all your queries. Must admit Iíve also enjoyed itó during part of these responses I got to poke my lance at the fallacies we hunters love so much. So thanks for the opportunity to join the frayóagain.

Patrick

6/10/00

From home (really!)