So far, a synopsis of INTERNAL BALLISTICS has been presented in P1. That has to do with what goes on inside our rifles when the trigger is squeezed.
P2 will give an overview of EXTERNAL BALLISTICS: The flight of the bullet from muzzle to impact. That is its muzzle velocity and impact velocity on target, or its trajectory and retained energy during its flight.
Multiple factors come into play in that sequence:
1> Muzzle velocity.
It is generally recognised that a “pointy” bullet will resist atmospheric drag better than a round-nose or flat-tip bullet. That is, they will retain their initial velocity (hence energy) better making the flight path “flatter” and impacting with greater velocity (energy and force) on target (game or other target such as animal silhouettes). As a concept, that’s not disputable. What does raise multiple questions, however, is what bullet in a particular caliber is best overall for the task at hand.
This part of our discussions on rifle ballistics will mostly focus on that dilemma. In the end, three considerations must be addressed: The cartridge, the bullet and muzzle velocity.
This designates rifle caliber. As one example, there are many .30-caliber cartridges — too many to name here, but we are all familiar with the ubiquitous .308 Winchester – that’s a popular .30-caliber cartridge that shoots bullets of .308″ diameter, same as the .30-06 Springfield and .30-30 Winchester. The rifles all have .308″ bores, but the size of the cases vary in capacity for gun powder. We already know that, but I’m making a simple point: We don’t expect a .30-30 burning upwards of 38 grains of medium-burn rate powder to be equal in ballistics to a .308 Winchester that may burn 52 grains of the same burn-rate powder behind the same weight bullet. And that despite the fact that the .308 Win can shoot more aerodynamic bullets than the .30-30 that shoots flat-nose or round-nose due to a tubular magazine. (Yeah, I know you can get a .30-30 in a single shot or you might still have one in a bolt-action hidden away in a closet that allows sharp-pointed bullets.)
But the premise being: there are .30-calibers and then there are other .30-calibers! So if our dream rifle is a .30-caliber there are multiple choices that WILL determine ultimate ballistics at the muzzle and on game.
While there may NOT be as many choices in some other cartridges as in .30-caliber, yet the same logic prevails: What do I want my rifle to be capable of doing for me? It could be as a general-purpose hunting rifle, or a very special heavy-barrel varmint-target rifle, or a test platform, or Big Bore for large and dangerous game, or just a big-game rifle suitable for any game in North America (and other places) under most conditions.
While I’ve owned three .30-06s, yet I’ve decided that for myself it’s something like driving a very reliable Toyota Corolla — reliable but boring!! There are more exciting cars that do the same things and more — better! That’s how I see the .30-06. The Corolla was great when economics and reliability was the favorite tune… but even the current CEO of Toyota, the grandson of the founder, Mr. Toyoda, said so recently! Changes are coming, no more boring Corollas — and it’s happening!
All that to state a fact: After we decide what rifle for the next big-game hunt, we are stuck with its ballistics. If I’m going to be “stuck” with the ballistic capabilities of my rifle for a particular hunt, I don’t want “just enough” to merely get me there (like a Corolla) but with a “driver” that generates some enthusiasm like a sport sedan. No, I can’t afford a sport sedan like Audi or Lexus, but I can manage a compact that acts like one! And most of us can afford at least one rifle with ballistics that can generate more than enough in accuracy and terminal effect, but also with passion!
(That’s who I am… but NOTHING is as important and ultimately fulfilling as knowing that my Father is THE ONE who made the universe and everything in it!)
I never had the means for a car that made 0 to 60 mph in 4 – 5 seconds, but I did in a motorcycle. Likewise, I want rifles that can “drive” like a sport sedan or a motorcycle –nothing “boring”. No, I agree, it isn’t wise or necessary to push a car or bike at over 100 mph to get “there” — wherever “there” might be, but it’s satisfying to know its available when a couple of middle-aged men pull up beside you at a stop light in a Corvette, and the driver speaks: “Want to give ‘er a try?”, making reference to my 750 Honda Custom. When it went green, I twisted the throttle and he pressed the gas to the next red light. We arrived together. His Corvette about 4.5 sec to 60 mph. My bike about the same. His Corvette? About $75,000. My 750 Honda? About $1600. (Yeah, I know, that was forty years ago!)
The point? You or I don’t need a custom rifle with all the bells and whistles to have “exciting” ballistics. A plain Jane Ruger No.1 comes in a variety of cartridge sizes with holes in the barrel to match. When I look down the shinny .458″ bore of mine it awakens passion, desire and motivation to go hunt something big and mean! Same for a .300 magnum. Today, at our local gun “emporium” there sits (along with some more costly “toys”) in a locked glass cabinet a rather inexpensive bolt-action repeater with a synthetic camo stalk chambered in .300 Weatherby Magnum. I’ve considered it a few times as I’ve previously owned one by the same maker. It bears the Weatherby Vanguard name and a sticker with $675 printed on it. Twenty years ago mine had a beautiful Claro walnut stock just like Weatherby’s most expensive, and it was a great rifle but more costly than this one with the synthetic stock. A .300 Weatherby, in my view, is anything but a boring rifle. For the handloader, it’s capable of firing a 180gr at 3200 fps from a 24″ barrel! Mine had a 24″. What do I think of the .300 RUM? Too much of a good thing, in my view. Especially if one wants to shoot more than 600 rounds through it without the barrel being fried!
What do I think of today’s cars? Better than ever! The best selling car in Canada is the Honda Civic — it looks fast sitting still! And it comes with a 4 banger that makes over 300 horses if you want that. Of course, it has a twin turbo. And the Corolla is looking much better, and you can even get that with more than a hundred horses. My four-banger drives like a sport CUV. It makes the same horsepower as the inline Buick 8 cylinder did “back in the day”.
As to rifles. they too are better than ever in my view and experience. And cheaper! An accurate .30-06 can be had for under $400, and it can be “cranked up” in horsepower to about 3300 ft-lbs at the muzzle by knowing “how to”. With today’s powders and bullets it comes very close to original ballistics of the hoary .300 H&H — the beloved of the nostalgic bunch. Hey, my rifles are for “ancient” cartridges — but they can hold their own if a younger man is seated at a bench beside me shooting a Ruger No.1 in .416 Rigby, loaded with 400gr Hornady SP bullets loaded for bear! Mind you, these were not max loads but were leaving his barrel at around 2230 fps. He didn’t seem to even like that much recoil! His had a 24″ and weighed in with scope at around 10 and 1/4 lbs.
When I arrived on the scene, he had just about finished his practice and testing session using a Chrony. Rather proudly, he invited me to view the results on the chronograph. Frankly, I don’t recall the exact number, but it was somewhere north of 2200.
He then enquired about my rifle. I had already placed mine in a setup for shooting 500gr Hornady SP Interlocs. The rifle was also a Ruger No.1, but in .45-70 with a long throat, which I called a “.45-70 LT”. I didn’t have my Chrony set up but offered my Ruger #1 to him to check MV over his Chrony. Yup, he did fire it and 2187 fps was recorded over his chronograph! He flinched and exclaimed ” WOW!! Corrected to MV I already knew what the results would be: 2200 fps/5373 ft-lbs! Recoil = 73 ft-lbs of KE! No extra weight added, just rifle and scope at 8.4 lbs. His by comparison: 400gr at 2230 fps/4416 ft-lbs (plenty for bear) from a 10.25 lb rifle = 46.7 ft-lbs recoil. Both had ancient ancestry (mine the most “ancient”) but easily matched more contemporary big-bore ballistics.
Many years ago, I was at the range doing some Chrony work for my .338 Win Mag in the Sako FS. A fellow shooter asked if I’d check some loads over the Chrony for his .300 Weatherby. I forget the exact barrel length, but likely 26″. Weatherby advertises their factory product of a 180gr at 3250 fps from a 26″. His loads recorded 3200 fps instrumental at the Chrony without correction. I think at the muzzle they would have been close enough to Weatherby’s claims. That’s 4221 ft-lbs at the muzzle and 2148 ft-lbs at 500 yards if it’s a Partition. The 200gr AccuBond, with a BC of .588, is only -3″ at 300 and 2470 ft-lbs at 500! THAT stirs my adrenaline! Comparing a .30-06 to that is like comparing an ’80’s Corolla to my ’56 Ford Fairlaine with a V8! Or… my close friend’s BIG ’59 Chevy with its in-line 6 to the V8 Ford of ’56. His was new and mine had a few years plus too many miles, but I left him in the dust on a twisty New Brunswick road back in 1959.
The cartridge determines ultimate ballistic capabilities.
Therefore it determines MUZZLE VELOCITY. And MV is in charge of downrange ballistics.
But some other factors are part of the act as well:
BULLETS > their weight and shape
Bullet weight in grains for a certain caliber determines its sectional density (SD) and has an important bearing on its ballistic coefficient (BC). SD also plays an important role in penetration at impact. BC is nose profile of the bullet and determines in large part how efficient the bullet is in maintaining its velocity to impact.
Bullet manufacturers give ratings in their manuals for both SD and BC. When we know MV and BC we can plug those into a ballistic software program (Hornady has one on the Internet — and there are others) for final velocity and kinetic energy at impact.
Once we know MV and downrange impact, we may use any number of guides to inform us of presumed results — whether just KE or KO (Taylor).
Mine will follow in P3.
is determined by the rate-of-twist of the rifling vs bullet weight and length. Its stability affects BC and how it performs at impact. An unstable bullet is usually caused by a too slow rate of twist or a worn barrel or a bullet that’s too long for the twist-rate.
If we see an oblong or eccentric shape bullet hole in the target we will need to check out the reason. A bullet that “keyholes” is one that hits the target sideways — that’s bad, very bad! The barrel’s rifling may be worn out or the bullet itself may be undersize.
Its caliber and weight determines its SD, which along with its MV, shape and construction will determine effect at target impact.
Let’s have a closer look at those in turn — Caliber now, and construction and shape in P3.
Caliber: that’s bullet diameter. How important is that? Well, for one thing it will play a major role on bullet weight which together determine SD that has a major role in terminal results — so, very important!
To illustrate by way of comparison, let’s think of two distinct and perhaps equally popular rifle cartridges based on the .30-06: The.25-06 Remington and the .35 Whelen. The .25-06 has bullet diameters of .257″ while the .35 Whelen has bullet diameters of .358″ — a sub-medium vs a medium bore.
Nosler’s component bullets for the .25-06 go from 85gr to 120gr, making it a somewhat versatile rifle for varmints, small predators and deer (whitetails, mule deer, etc.). Some call it a duel-purpose rifle.
Nosler’s manual #6 presents three projectiles in .358″ — a 180, 225 and a 250. Hornady markets five: a 180 SP, a 200 in RN and SP, as well as a RN and SP in 250gr. Woodleigh offers a 310gr. And there are other companies that make .358″ bullets as well. We could even make our own by casting them.
Common sense should tell anyone with a smidgen of ballistic knowledge that the two cartridges are intended for different species of game — the .25-caliber for small and medium game while the .35-caliber was mainly created for big game like elk, moose and bears, both blacks and brown.
But aside from the history involved in their creation, let’s have a closer look at their ballistics by choosing the best Nosler Partition for each. That would be a 120gr in .25-cal and a 250gr in .35-cal. Have we noticed that the main bullet for larger than varmints in .25-cal is less than 1/2 the weight of the common large game bullet for the .35? But, more than that, there’s a significant distinction in SD, BC and cross-section area! Yeah, the 250 is slower but will always carry much more energy and momentum to target!
The point of that paragraph is to demonstrate, once again, that the larger caliber based on the same cartridge will ALWAYS be superior than the smaller one in the taking of larger game, assuming bullets have the same structure and shape.
Here are the numbers for the two cartridges in our example:
Cartridge: .25-06 (based on the .30-06)
Barrel length = 24″
Bullet make and weight: 120gr Nosler Partition
SD = .260
BC = .391
MV = 3175 fps/2685 ft-lbs/36 TE/ -1.60″
100= 2934 fps/2293 ft-lbs/31 TE/ +2.17″
200= 2706 fps/1951 ft-lbs/26 TE/ +1.89″
300= 2489 fps/1651 ft-lbs/22 TE/ -3.15″
400= 2283 fps/1388 ft-lbs/19 TE/ -13.8″
Cartridge: .35 Whelen (based on the .30-06)
Barrel length = 22″
Bullet make and weight: 250gr Nosler Partition
SD = .279
BC = .446
MV = 2600 fps/3752 ft-lbs/106 TE/ -1.60″
100= 2414 fps/3233 ft-lbs/ 91 TE/ +3.67″
200= 2235 fps/2772 ft-lbs/ 78 TE/ +2.94″
300= 2064 fps/2364 ft-lbs/ 67 TE/ -4.77″
400= 1901 fps/2005 ft-lbs/ 56 TE/ -20.7″
Obviously, by simply making the .30-06 cartridge/case to have a larger caliber, ballistic results are INCREASED both at the muzzle and on target downrange, all else being equal.
On the other hand, by necking the .30-06 case to a smaller caliber (including the .270 Win) ballistic results are DECREASED at the muzzle and on target downrange, all else being equal including PSI.
So larger calibers have greater ballistic potential than smaller calibers, all else equal, including equal PSI, barrel length, case capacity and OPTIMUM bullet weights (shape and construction) for the cartridge. That’s why a .338 Winchester Magnum can NEVER equal it’s parent case, the .458 Winchester Magnum under the same qualifiers mentioned above.
That’s not seriously debatable. Yeah, some will argue based on a “better” bullet selection for their “lesser” caliber at higher pressure… but you already know what I think of that kind of obfuscation (smoke screen)!
Til the next on P3