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Wednesday, 6 April 2016

Calibre & Performance: Size isn't Everything eh:

From time to time I read a lot of old bollocks - sometimes it has to be said, in a 'murikan' or 'ozzie' accent. - but I'm not really complaining as you can't beat a good stimulating argument eh.

There may be folk who think that anything other than a MAGNUM doesn't work.

.358", .357", .356",    .314", .312",      .223"
As Measured With My Mitutoyo Micrometer

Not much difference to see here until you drop-down to the .22" rim fire eh.

- So starting at the top - here is a table that shows the difference in size - reducing as you go down from WHOAAR! to squeak ....

Some Familiar Handgun Cartridges:

500 S&W = .500"
- 0.025"
480 Ruger = .475"
- 0.021"
45 Colt = .454"
- 0.002"
45 ACP = .452"
- 0.023"
44 Magnum = .429"
- 0.019"
41 Rem. Magnum = .410"
- 0.010"
10 MM Auto = .400"
0.000
40 S & W = .400"
- 0.043"
357 Magnum = .357"
0.000
38 S&W Special = .357"
- 0.002"
9MM Luger, NATO = .355"
- 0.043"
327 Federal Magnum = .312"
0.000
32 Smith & Wesson = .312"
- 0.061"
.25" Auto Colt Pistol = .251
-0.028"
.22 Long Rifle Rim Fire = .223"
- 0.051"
.17 Hornady Magnum Rimfire = .172"

(Funny how the names get bigger as the size gets smaller eh)

- Now, Bubba, put your banjo down and pay attention:
- Do you think that you could tell the difference between a 44 Magnum bullet thrown at the back of your head by your sister - and maybe a 0.029" smaller (that's twenty-nine thousandths of an inch ) 10MM Auto that lands in the same spot? (- sister "Ginnie" is a re-loader with a strong right arm).


Or - how about this for a science quiz: How much more fluid might flow out of a potty (or 'guzunder') whacked by a .32" calibre 327 Federal Magnum round moving at more than 1,600 feet per second - than out of the hole created by a .45ACP at 830 feet per second?


Shhh, but now own up - which of you didn't know that a 44 Magnum bullet measures a mere 0.429"?

There is more than effective size to consider eh - we should also be regarding mass(weight), muzzle velocity, hardness, deformability, frangibility, shape, stability, accuracy, range, .. how about 'hydrostatic shock' or 'momentum transfer' or expansion or temporary cavitation?

The physics involved may be described as 'multifactorial' - and the passage of time yields improved strength materials that combine with better chemistry propellants to give much higher performance in smaller packages.

- Consider that the "wimpy .32" calibre" 327 Federal Magnum is now using an internal pressure limit of 45,000 p.s.i to give muzzle velocities exceeding 1,600 foot per second - (try 115gn. @ 1,659ft./sec.) - while having less recoil than a 357 Magnum. (But I bet it barks a bit in a short barrel!)

Note: The pressure ceiling for the old .30" Carbine is 40,000 p.s.i. - The older 32-20(.32WCF) is 16,000 C.U.P

                                             
Modern Expanding .25acp Ammunition.

Don't mess with Grand Ma, she's not old,
Hear that story about a stranger bold,
He laughed and said, "One foot in Heaven",
Till she turned and fired her .327...
Thomas Arthur Bridges III

Marty K.