24 January 2008

More Thoughts on Forsyth

A long, long time ago, at a backwoods rendezvous, I discovered the following truth printed on the back of a well-worn t-shirt being sported by a gal who looked equally well-worn. The message read:

“It takes balls of lead to be a muzzleloader.”

Sometimes the Universe provides enlightenment in the most peculiar ways!

In an earlier posting about Forsyth rifling I expounded on my reasons for using it for the hunting rifles that I build. I commented about the effectiveness of big round balls in decisively dispatching game and my preference for them over the “new” sub-caliber bullets cocooned in plastic sabots. I do understand all the hype that this new fad is all about achieving higher velocities (translate as killing energy) at greater distance than is generally believed feasible with old-fashioned round balls. In my opinion, the validity of those claims is open to debate.

After reading my comments on Forsyth’s rifling concepts, one of our readers replied that round balls just don’t perform as well as higher velocity pointed muzzleloader bullets at ranges beyond 60 or 70 yards. I’m willing to bet that like so many others, he derived that conclusion from reading ballistic data for round balls.

While I have to admit that downrange velocity and foot-pound numbers don’t seem very impressive when it comes to big round balls, there is an element of the power equation that is sorely lacking from simple ballistics charts – one that is consistently overlooked by the crowd. A concept that, once understood, will forever change the way you think about big round ball projectiles. That missing element is momentum.

If we are to consider and believe in paper ballistics alone and ignore actual performance in the field, we would be lead to believe that the .243 Winchester outperforms the old soldier, .45-70 Government, in its ability to put down big game.

However, the facts of the matter are quite the opposite as we all know. But we tend, nevertheless, to continue to use simple two-element paper ballistics equations as we seemingly lack for a basis of comparison of performance between various loads, be they cartridge or loose powder and ball. Regardless of which, the point is that we continue to draw the wrong conclusions about their effectiveness on game when comparing by mere velocity and energy numbers.

This puzzling situation is nothing unique to us moderns and has, in fact, been carefully contemplated many long decades ago by the famous African hunter, John Taylor. Taylor early realized that paper ballistics derived from simple Newtonian calculations did not account for the ability of big bullets lumbering along at moderate velocities to put down really tough game with a single shot when compared to smaller-bored higher-velocity bullets.

He postulated that the missing element of the power equation was bullet diameter. Including the bullet diameter in the equation provides a three dimensional view of the power dynamic while providing insight to the big round ball's seemingly magical ability to take down big game like it had been struck by the hammer of Thor.

In order to more fairly compare bullets and their effectiveness on game (disregarding other variables, such as bullet design i.e. jackets, ogive, metal temper, etc.), Taylor devised an equation that included the all-important bullet diameter which changes the performance values tremendously and provides a much more accurate basis of comparison by including the frontal area, that is, the striking area of the projectile. This is the actual surface area by which that all-important momentum is transferred into the target. Appropriately, it is termed the "Taylor Knock Out" formula.

When we apply the TKO to our humble, unsophisticated round ball traveling at higher (than average) velocity, we soon realize that we are not as handicapped as the purveyors and disciples of sabots and pointy bullets would have us believe! (By the way, the word, "sabot" is pronounced, sah-boe' - French for "shoe".)

The application of Taylor’s formula to ballistic data results in a simple numerical value that allows easy comparison that any non-rocket scientist can understand and appreciate. The formula is very simple to calculate where the muzzle Velocity (expressed in feet-per-second) is multiplied by the Diameter of the bullet (in thousandths of an inch) times the Weight of the bullet (in grains) and the product thereof is divided by 7000 (the number of grains in 1 pound). The resulting number expresses a Knock Out value which then becomes the new basis of comparison.The higher the Taylor value, the greater the knockdown power.

As an example, let’s take our old standby, the .30-06, launching a 180-grain bullet at 2700 feet-per-second. By multiplying the Velocity, 2700 fps, by Diameter, .308, we get 831.6 which is multiplied by the Weight in grains, that being 180. The product of 149,688 is then divided by 7000 which provides a Taylor Knock Out value of 21.384 or simply 21.4. Using this formula, the .300 Winchester with the same 180-grain bullet churns up a Taylor value of 24.3. The .45-70 plodding along with its factory-loaded 405-grain bullet renders a Taylor value of 34.4. Not what you had expected, Ill bet.

Yes, but you argue, those values are based on muzzle velocity and the downrange numbers will be much lower as that 405-grain flat-nosed slug runs out of steam - and even more so for a big round ball - right? While true to an extent, the loss is not as bad as you might think. One can easily calculate the downrange Taylor value of any projectile simply by running the equation and plugging in the velocity at a specific distance from the muzzle.

In this example, the limitation on the .45-70 or, in our case, big round ball projectiles, is not lack of knockdown power, it’s the low velocity and the resulting rainbow trajectory of the bullet which is so bowed that accurate placement within the vital zone on game becomes rather iffy beyond 80 yards that is the limiting factor. Unless, of course, you have years of field experience in accurate range estimation - or a range finder. (As stated in the earlier post, we achieve flat trajectories with higher velocity than usual - which can safely be achieved with Forsyth rifling in a good solid rifle.)

Now spurred by our reader’s comment, I had reason to conduct the research and have the following table of data that will provide some interesting numbers on my .62 caliber Faeton’s 320-grain round ball departing the muzzle at 1700 feet-per-second and it’s downrange values as well.

WARNING: Kids, do not try this at home. Do not attempt to load any other .62 caliber muzzleloader to achieve this velocity unless it is deemed to be safe by its manufacturer. I know it to be safe in Faeton rifles that I build utilizing Forsyth rifling. I refuse all liability for the experiments and misdeeds of others. If in doubt, buy a Faeton. (I know that’s a pretty blatant plug, but it is my blog, after all…)

It was that conformant wisdom (translate as "time-honored erroneous assumption") that the muzzle-loaded round ball runs out of poop after 60 yards that really irritated me and became the challenge to drive a stake into the heart of this myth and settle the issue once and for all. I proceeded to calculate the Taylor values for renowned center-fire rifle loads and compared them to the downrange Taylor value of the .62 Faeton. That’s when things really got interesting, as the chart reveals.

Clicking on the chart will enlarge it for easier viewing. Then click the "back" arrow at the top left of your screen to return to the text.

Before making comparisons, however, it must be understood that the Taylor value for the cartridges listed is their knockdown power AT THE MUZZLE. In other words, the Faeton’s knockdown power at 150 yards is about equal to the knockdown power generated by the .340 Weatherby at the muzzle.

Another advantage of the higher velocity obtainable with the Forsyth system is a very flat trajectory. Looking closer at the chart indicates the ball actually rises above the line of sight very little on its trip to the 100 yard mark and then dips a mere 2.7 inches at 120 yards providing virtually a point blank range of 125 yards. No range estimation or hold-over needed - just aim and shoot.

To my way of thinking that’s pretty amazing for a big-bore round ball rifle!

“Yes, but what about accuracy beyond 60 or 70 yards?” he asks. The Faetons that I craft will usually shoot into 3 inches at a hundred yards without much fuss. However, if you get seriously anal they can be made to shoot much tighter. But I question whether super-tight groups are really all that important in putting meat in the freezer.

When I was a much younger man I knew an “old” guy (he was all of 50!) that went deer hunting every year. He wasn’t a gun enthusiast, but he was a hunter. When first introduced to this man, and learning that he enjoyed hunting, I asked what kind of rifle he used. He said it was an “old 30-30 rifle” that was his dad’s and knowing that I was interested in firearms, he asked if I wished to see it. Of course, I wanted to see it! It’s a gun, right?

As it turned out, his “old 30-30 rifle” was actually a .38-55 Winchester Model 1894 with a full octagon barrel and crescent butt plate. I explained that it wasn’t actually a .30-30, but rather a .38-55. He seemed disinterested in the technicalities, but went on to say that the shells were specially ordered for him by the guy down at the hardware store.

The point of all this is that this technically unsophisticated man put meat in the freezer every fall with that rifle – without fail. In further conversation I learned that he did not go to the range and burn up a box of shells sighting in before the season. In fact, he had the same box of shells that he had ordered 6 years earlier!
He said that before he went out for the season he would take a shot at a coffee can that he placed about 50 yards away to make sure the rifle could still “hit,” as he put it. Then he would go do the deed. This man was not a particularly good shot, either. But he was a good hunter.

The moral of the story? Yes, there was a point to that trip down memory lane… I believe we are getting sidetracked by all the hype about the "advantages" of shooting plastic-wrapped pointy bullets and this holy grail quest for muzzleloading rifles that will shoot sub-minute of angle groups. Personally, I don’t see any advantages to plastic-wrapped bullets, but instead, a lot more fuss to load and shoot accurately in the field.

If we are good hunters, a rifle capable of shooting sub-minute of angle groups isn’t going to put meat in the freezer any easier or with more efficiency than a rifle that shoots less than sub-minute of angle. Nor will that tack driver rifle make a good hunter out of an inexperienced hunter. As one old friend once told me in regard to all aspects of shooting, and certainly about putting meat in the freezer, “It’s the loose nut behind the trigger that makes the most difference.”

And just for the record, contrary to nasty and vicious rumors, I hold no disdain for new-fangled, non "traditional" muzzleloading guns. In fact, I have a few designs for such of my own and they look great wearing a scope and can burn synthetic powder and shoot pointy bullets into tight little groups, too. In my opinion, they do have their place - right along side cartridge guns with scopes to be used in center-fire hunting seasons - not in a primitive firearm season.

I don't wish to deprive anyone the joy of our sport. I just don’t want to see our newer muzzleloading brethren being duped into thinking that the old tried and true, easily loaded, sufficiently accurate, (big) round ball can't bring home the bacon in our marvelously modern world. And, that it doesn’t take surgically-accurate rifles to put meat in the freezer – just better hunters.

So, what does all this have to do with Forsyth rifling? It is Forsyth rifling which allows us to safely achieve those high velocities that elevate the lowly, unsophisticated round ball into the realm of performance of some of the most successful cartridges of all time.

One just cannot imagine how effective a big round ball, traveling at high velocity, is at anchoring game on the spot with a single well-placed shot. You have to experience it to believe it. Once you do, you'll be hooked. I have over ten years of feedback from Zephyr and Faeton owners who wholeheartedly agree.

For those open-minded folks who would like to read James Forsyth's wonderful book, The Sporting Rifle and Its Projectiles, the second edition is now in the public domain. If you're not able to locate it, feel free to e-mail me and I'll be happy to send it to you in e-book form.

As I said before, Forsyth had it all figured out 150 years ago!


buffler said...

Actually, some thought has been put into this in the past. The TKO expresses well the idea that the momentum, rather than the energy, of the projectile is important re killing power. Momentum is of course mass X velocity. The frontal area probably has to do with the efficiency of momentum transfer.

Lee said...

Thanks for doing this blog. I greatly enjoy it and agree with you completely. I have two pacific underhammers, a 62 and a 72. This past fall I dropped a Montana mule deer buck with the 72. The .700 round ball smashed both front legs the top of the heart and continued on it's way through the woods. Yes, probably over kill for a deer but I was elk hunting too. So I really believe in big round balls.

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About Me

Roger Renner

Hi. I've been a student, admirer, and designer/builder of underhammer guns for over 30 years. In that span I've built over 200 semi-custom underhammers exploring the possibilities from the ordinary to the exotic. In 1996 I founded Pacific Rifle Company to explore the market's interest in a high-quality underhammer rifle. Thankfully, that interest was, and still is, there. I sold PRC in 2006 but continue to craft high-end underhammers as I am truly afflicted with underhammeritis - which can be contagious!