Sunday, December 23, 2012

Revolvers are shockingly inefficient

I was over at Ballistics By The Inch, checking out barrel length data on the .357 Magnum, when I noticed that revolvers lose quite a lot of energy versus non-revolver designs. Remembering that revolver barrels are measured differently than those of fixed-chamber designs (for a .357 Magnum gun, add about 1.65" to the nominal length to compensate for the cylinder), we see a dramatic difference in energy produced between the T/C Encore and the Colt Python:

(Given that the barrel-plus-chamber length of the Python is approximately 7.65", I am estimating a 7.5" barrel for the Encore by averaging the performance from 8" and 7" barrels.)

7.5" T/C Encore

Cor-Bon 110 gr. JHP: 484 m/s, 837 J

Cor-Bon 125 gr. JHP: 554 m/s, 1,244 J

Cor-Bon 140 gr. JHP: 516 m/s, 1,210 J

Cor-Bon 125 gr. DPX: 520 m/s, 1,094 J

Federal 125 gr. JHP: 549 m/s, 1,221 J

Federal 158 gr. JHP: 470 m/s, 1,133 J

6" (actually ~7.65") Colt Python

Cor-Bon 110 gr. JHP: 390 m/s, 541 J (35% lost)

Cor-Bon 125 gr. JHP: 419 m/s, 710 J (43% lost)

Cor-Bon 140 gr. JHP: 362 m/s, 593 J (51% lost)

Cor-Bon 125 gr. DPX: 401 m/s, 650 J (41% lost)

Federal 125 gr. JHP: 420 m/s, 713 J (41% lost)

Federal 158 gr. JHP: 358 m/s, 657 J (42% lost)

Oddly, the 4" S&W loses less energy than the Colt. There are a number of factors that could account for this  (smaller gap, tighter rifling, tighter forcing cone, etc):

5.5" T/C Encore

Cor-Bon 110 gr. JHP: 433 m/s, 667 J

Cor-Bon 125 gr. JHP: 507 m/s, 1043 J

Cor-Bon 140 gr. JHP: 468 m/s, 996 J

Cor-Bon 125 gr. DPX: 488 m/s, 964 J

Federal 125 gr. JHP: 499 m/s, 1008 J

Federal 158 gr. JHP: 433 m/s, 958 J

4" (actually 5.67") S&W 686

Cor-Bon 110 gr. JHP: 409 m/s, 595 J (11% lost)

Cor-Bon 125 gr. JHP: 450 m/s, 821 J (21% lost)

Cor-Bon 140 gr. JHP: 391 m/s, 695 J (30% lost)

Cor-Bon 125 gr. DPX: 438 m/s, 779 J (19% lost)

Federal 125 gr. JHP: 438 m/s, 776 J (23% lost)

Federal 158 gr. JHP: 380 m/s, 739 J (23% lost)

So, in general, you're probably losing somewhere between 20-40% of your energy because of the cylinder gap.

For comparison, here's 9mm Luger from both a 7.5" and 5.5" Encore and a 4.875" barreled Beretta 92FS:

7.5" T/C Encore

Cor-Bon 90 gr. JHP +P: 495 m/s, 717 J

Cor-Bon 115 gr. JHP +P: 443 m/s, 730 J

Cor-Bon 125 gr. JHP +P: 411 m/s, 694 J

Cor-Bon 115 gr. DPX: 414 m/s, 639 J

Federal 115 gr. JHP: 375 m/s, 523 J

Federal 124 gr. Hydra-Shok JHP: 357 m/s, 512 J

Federal 147 gr. Hydra-Shok JHP: 318 m/s, 482 J

5.5" T/C Encore

Cor-Bon 90 gr. JHP +P: 473 m/s, 653 J

Cor-Bon 115 gr. JHP +P: 423 m/s, 666 J

Cor-Bon 125 gr. JHP +P: 395 m/s, 633 J

Cor-Bon 115 gr. DPX: 404 m/s, 607 J

Federal 115 gr. JHP: 359 m/s, 480 J

Federal 124 gr. Hydra-Shok JHP: 342 m/s, 471 J

Federal 147 gr. Hydra-Shok JHP: 311 m/s, 459 J

4.875" Beretta 92FS

Cor-Bon 90 gr. JHP +P: 464 m/s, 628 J

Cor-Bon 115 gr. JHP +P: 422 m/s, 663 J

Cor-Bon 125 gr. JHP +P: 394 m/s, 628 J

Cor-Bon 115 gr. DPX: 390 m/s, 568 J

Federal 115 gr. JHP: 343 m/s, 438 J

Federal 124 gr. Hydra-Shok JHP: 340 m/s, 464 J

Federal 147 gr. Hydra-Shok JHP: 302 m/s, 433 J

9mm +P is hot stuff, producing around 80% of the energy of .357 Magnum as fired from a revolver. Most modern 9mm handguns are fine with shooting a steady diet of +P ammunition, in fact more so than some .357 Magnum revolvers are with shooting factory magnum ammunition.

Wednesday, December 5, 2012

New Name

It's a bit more unique and a bit less assuming. The old URL will redirect here.

The Cheaper Man

It is often repeated in gun nut corners of the Internet that small "spray and pray" rifles (as some derisively call weapons like the AR-15 or AK) are not needed, if one only is willing to train their soldiers and marines better.

They clearly haven't read their Kipling:

A great and glorious thing it is
To learn, for seven years or so,
The Lord knows what of that and this,
Ere reckoned fit to face the foe--
The flying bullet down the Pass,
That whistles clear: "All flesh is grass."

Three hundred pounds per annum spent
On making brain and body meeter
For all the murderous intent
Comprised in "villainous saltpetre!"
And after--ask the Yusufzaies
What comes of all our 'ologies.

A scrimmage in a Border Station--
A canter down some dark defile--
Two thousand pounds of education
Drops to a ten-rupee jezail--
The Crammer's boast, the Squadron's pride,
Shot like a rabbit in a ride!

No proposition Euclid wrote,
No formulae the text-books know,
Will turn the bullet from your coat,
Or ward the tulwar's downward blow
Strike hard who cares--shoot straight who can--
The odds are on the cheaper man.

One sword-knot stolen from the camp
Will pay for all the school expenses
Of any Kurrum Valley scamp
Who knows no word of moods and tenses,
But, being blessed with perfect sight,
Picks off our messmates left and right.

With home-bred hordes the hillsides teem,
The troop-ships bring us one by one,
At vast expense of time and steam,
To slay Afridis where they run.

The "captives of our bow and spear"
Are cheap--alas! as we are dear.

Arithmetic on the Frontier, by Rudyard Kipling

Certainly, great skill is required to accomplish certain things, like flying a helicopter, and those that perform their tasks well will be pound-for-pound better than those that do theirs poorly. Yet, it is the sorry reality that skill at something does not scale linearly with training. If a rapid course in riflemanship takes 20 hours, but total mastery takes 10,000 hours, then a nation holding its soldiers only to the standards of the rapid course will be able to field two and a half orders of magnitude as many soldiers as the latter. Is a master rifleman good enough to kill 500 "OK" riflemen? Most likely, no.

The ubiquity of special forces in militaries worldwide speaks to a recognition of the value of great skill in warfare, but for the average soldier, the appropriate standard is usually the lowest one that's still capable of carrying out the task given to them.

Saturday, December 1, 2012

The Largest Centerfire Rifle Ever Made?

So claims the title of this video, showcasing JD Jones' very large .950 JDJ rifle.

I've seen this video swimming around on the Interwebs a few times, usually with that claim either in the title or description.

Is the .950 JDJ rifle the largest centerfire rifle ever made?

The answer is "it's complicated" and also "no".

The qualification of "centerfire" begs the question: Does electrical priming count? It's normally located in the center of the cartridge, and it is a priming method, so is it "centerfire" or not? If it doesn't count, does that mean that the .950 JDJ is the largest bore cartridge that primes via standard Large Rifle Primers? If so, why is that significant?

Beyond that, we can then argue whether "rifle" refers to a firearm that is shoulder-fired and rifled, or just rifled, because neglecting the shoulder-fired requirement, there are of course a whole host of larger-caliber weapons than the .950 JDJ. For the purposes of this article, I'll assume that "rifle" refers to any firearm that is shoulder-fired and rifled, because that makes the competition much more interesting.

In fact, a number of centerfire rifles out-bore the .950 JDJ. The XM109, a 25mm anti-materiel rifle, has a bore of around .973". There are numerous 4-bore rifles in the world, and, though the exact diameter of a "4-bore" varies from maker to maker, a number of them measure over 1" in diameter. The video I just linked even proves that the .950 JDJ isn't even the largest bore centerfire rifle to become an Internet sensation!

Moving on, every grenadier who served from Vietnam until now should raise an eyebrow at the title of this video, as they used rifles of much greater diameter during their service.

Going even bigger, we have the various recoilless rifles of the world. While perhaps the most famous, the 84mm Carl Gustav does not actually qualify for the purposes of this article, because it is side-priming. However, numerous centerfire recoilless rifles exist. Among those that are also shoulder-fired, we have the M18 57mm (2.24") rifle, which has almost 2 and a half times the bore diameter of the JDJ (more here, and here); and the M67 90mm (3.54") recoilless rifle, with a bore nearly four times as wide as the JDJ.

At the risk of going a bit smaller, there's also the very interesting 76mm High Impulse Weapon System, which is notable in that it does not redirect any of the energy of the cartridge to help mitigate recoil.

This isn't intended to be a slam post against JD Jones; they make some really interesting stuff. I bet that .950 is a hoot to shoot (though maybe the one guy with a cracked rib didn't think so), but just remember, the next time somebody claims to have made the "largest", "biggest" or "most powerful"... They've probably been outdone before they even started.