Re: 15mm rifles

In Message-Number: 6352 Peter H. Brenton [email removed] writes:

> [email removed] (Mark Urbin) says;
>
> >  I noticed someone
> >was designing a *large* rifle.  In the 15mm range.
>
> for those of us not particularly familiar with real-life weapon
> diameters (or at least not in millimeters) could you put this into
> context please?

OK, the largest caliber sniper rifles currently in use today (the RAI
Model 500 and the Barrett Light .50) fire the .50 Browning round (the
same shell used in a Browning .50 caliber heavy machinegun of WWII
fame).  That's a 1/2 inch diameter slug, which works out to 12.7mm.

The largest caliber American centerfire cartridge ever produced (and
now obsolete) is (was) the 70-150 Winchester.  Developed as a novelty
in 1888, it was based on a brass 12-gauge shotgun shell, which was
shortened and necked slightly.  A specially manufactured Winchester
1887 shotgun (with a rifled barreled) was created to fire it.  Neither
the weapon or the shell were ever produced in commercial quantities.
It would have been considered a 17.9mm rifle.  Ouch.

The largest sporting round currently in production is a proprietary
(wildcat) cartridge called the 700 Nitro Express.  It includes a slug
that is .7 inches in diameter (making it a 17.78mm weapon) and, as
the name implies, being shot with it is like being hit by a train.
There's not much recognizeable left afterwards.  With a muzzle velocity
of 2000 fps and a muzzle energy of 8900 fpe, it is the most powerful
sporting cartridge in the world.

> I *thought* that a 30-06 rifle had a round 6/10ths of an inch in
> diameter (this doesn't sound right to me).

You're right, it *isn't* right. :^)  The 30-06 U.S. Springfield (as
the round is formally described) uses a slug .308 inches in diameter,
which would make it a 7.8mm rifle in MT terms.

>                                             That would make it
> (using my thumbnail approximation of 25 mm to an inch) about
> 15mm diameter.  This can't be right if your talking about 15mm
> being a *large* rifle, I assume your talking about an elephant
> rifle, not a deer rifle.  Could someone please correct me?

Done.  See above. :^)

> It would also be helpful to me if someone could post a list of
> standard 'real' weapon calibers and show their diameter in mm
> (ie. .357 Magnum=XXmm pistol).

Sure.  Here are some of the more common handgun calibers (for weapons
not already described in millimeters):
        .22*      = 0.223mm (*=short, long & long-rifle)
        .25 ACP   = 6.38mm
        .32 ACP   = 7.85mm
        .380 ACP  = 9.04mm
        .38 Spec. = 9.07mm
        .357 Mag. = 9.07mm
        .40 S&W   = 10.16mm
        .41 Mag.  = 10.41mm
        .44 Mag.  = 10.9mm
        .45 ACP   = 11.48mm
 ...and for centerfire rifle calibers:
        .243 Winchester      = 6.17mm
        .270 Winchester      = 7.04mm
        .30-30 Winchester    = 7.62mm
        .308 Winchester      = 7.62mm
        .458 Winchester Mag. = 11.63mm
        .460 Weatherby Mag.  = 11.63mm
        12-gauge shotgun     = 18.5mm (bore diameter, open choke)

Bare in mind that while one caliber may be equal to or larger than another,
it is by no means safe to assume that size equals power.  The .38 Special
and .357 Magnum handgun rounds use slug with identical diameters, but
the .357 is much more powerful.

In addition to the above rounds, we've already got handgun rounds in
9mm and 10mm, plus rifle rounds in 5.56mm (NATO), 7mm, and 7.62mm (also
NATO).  There are others, but they tend to run towards the more exotic.

> Of course, I was always a fan of the very thin very high velocity round
> which should have a better penetration than any large (non-explosive) round
> in any case.  It will also, of course, do less damage (which is why you fire
> a three round burst, or full auto)

This may be true for infantry weapons, but for tanks, it's a different
story entirely.  The most effective anti-armor shell currently in use
by the U.S. Army's M1A2 MBT (main battle tank) is the 120mm APFSDS
(Armor-piercing, Fin-stabilized, Discarding-sabot) round.  It throws
a 10 lb. tungsten carbide 'flechette' at almost 5,500 fps.  When it
hits enemy armor (BTW, it can penetrate up to 15" of steel), it drives
throw the plating, disintegrating as it goes.  By the time penetration
is complete, roughly 100 fragments (from the dart and enemy tank hull)
over 1 oz. each, plus over 600 smaller fragments, are moving inside
the target at velocities still in excess of 2,800 fps.  What happens
to the enemy tank crew at that point is best left to the imagination
(although I do have a document that details the results, if anyone
is morbid enough to care.)

Later,

        Mark F. Cook

USMail: Hewlett-Packard
        Workstation Technology Division - Corvallis (Tech. Marketing)
        [address removed]

INTERNET: [email removed]
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