From:     "Edward J. Rudnicki" (FSAC-SID) <erudnick@pica.army.mil>
Subject:  Re:   Re: Bofors 40mm AA in WW2
Organization: NCR Corporation -- Law Department
Date: Fri, 20 Nov 1992 15:23:20 GMT


From     "Edward J. Rudnicki" (FSAC-SID) <erudnick@pica.army.mil>






Dave Pierson writes:
#
#In article <Bxo1D0.6H3@law7.DaytonOH.NCR.COM>, ntaib@silver.ucs.indiana.edu
#(Iskandar Taib) writes, in part:
#
#
#>It suddenly struck me that throughout all this, the usual
#>American practice of expressing things in inches seems to
#>have been abandoned by the artillery people. While the Bri-
#>tish stuck to their peculiar "how much does an iron ball
#>of this diameter weigh" measure, the American gunners seem
#>to have adopted millimeters while the rest of the country
#>was still thinking in terms of thousandths of inches, inches
#>and cubic inches - I imagine a 76mm gun might be called a
#>6.08 caliber gun.. was this due, perhaps, to American sol-
#>diers using French equipment during the First World War?
#
#	hmmm?  25.4mm/inch.  a 75 mm gun is a 3" gun (more or less.).
#	The next common US caliber is 105mm (4"), then 155 (6").  The 20mm/40mm
#	etc are "strictly metric".  The odd thing, to me, os that so much of
#	the world stayed "inchcentric": German 76mm, Russian 77 mm, German
#	88 mm (~3.5"  3.46...").
#
#	(rumor has that the 106mm recoiless was so named so that the logistics
#	crew could, at a galnce tell the difference between 105mm (conventional)--MORE--(85%)
#	and 106mm (recoilless...) ammo.
#


The US did use both inch and metric (M10 3 inch gun motor carriage and
8 inch howitzer vs 105mm and 155mm howitzers.) because of the French
systems inherited from the GReat War.

The 105mm is more typically written as 4.1", more often when English texts
refer to German weapons, i.e. the 10.5cm becomes 4.1" and the 15cm becomes
5.9".

Similarity in calibers in WW2 occurs because those sizes make sense, and no
doubt that fact occurs to the designers semi-independently. There are
however subtle differences:

French (and US) 75mm, British 17 pdr (76mm), German 7.5cm, Russian 76.2mm
(30 lines - 10 lines to the inch).

The British 25 pdr, German 8.8cm, Russian 85mm, and US 90mm are all in
the same neighborhood.

Further up there was the French/US 105mm, German 10.5cm, and possibly the
British 4.5 inch.

The Russian 122mm and German 12.8cm sort of stand alone.

In the medium artillery area there are the German 15cm, Russian 152mm (60
lines), French/US (and now rest of world) 155mm.

So yes, there is an apparent "inchcentricity" to gun sizes, but upon
closer observation it may be seen to be coincidental.



AS to the 106mm RCL, it is called that because there was an earlier
105mm RCL gun, and rather than having two non-compatible families of
105mm RCL ammo around, the nomenclature change was made. There was
little chance of confusing the ammo with standard 105mm howitzer or
tank gun ammo in any event, due to extreme differences in appearance;
a much greater source of confusion was between 155mm howitzer and 155mm
field gun ammunition, especially projectiles. This is still evident in
today's TMs, which caution against using projectiles marked "155G" in
155mm howitzers, even though the 155mm gun is long out of US service.



Ed Rudnicki     erudnick@pica.army.mil     All disclaimers apply
"War must be looked upon as a business, and subject, like any other business,
to business principles. War is the business of destruction of life and
property of an enemy.....The most deadly and destructive implements of war
are the most humane, and the producers of them may justly be looked upon as
humanitarians."     ----- Hudson Maxim (the other Maxim)

Newsgroups: sci.military