35
« Last post by Pete George on October 21, 2023, 04:34:28 PM »
Dave wrote:
> The Heavy Arty book lists examples of 11? smooth bore shells but no wall thickness of course.
> I was just curious if anyone had a known 11? frag with a similar thickness (1.95?).
Because during the past 40 years I've very frequently been asked to correctly identify artillery shell fragments, I long ago put some serious study into answering your question about cannonball shellwall thickness.
Go to the US Ordnance Manual of 1861, and consult the first chart on page 34. That page's title is "Chapter Second -- Shot and Shells -- Nomenclature, Dimensions, Weight.) The first chart on that page tells the shellwall thickness of all cannonballs except for a 9"-caliber shell. For example, it says:
8"-caliber, AVERAGE (a.k.a. "True") shellwall is approximately 1.5-inches.
10"-caliber, average thickness is approximately 2.0-inches.
Therefore, Dave, your Spanish Fort frag is from a 10-inch Common-Shell. (Note, the Case-Shot shellwall is thinner.)
For those of you who are interested in the "missing data" for a 9-inch caliber shellwall:
I've attached (below) a scan of an 1854-dated diagram from the US Bureau of Naval Ordnance. It shows a 9"-caliber shellwall's thickness is 1.6-inches. However, it seems to average about 1.7-inches thick in the frags I've personally measured from wartime production 9" roundshells.
In closing, a cautionary note:
Always remember, as we've seen in sawed-in-half shells, the powder-cavity is often erroneously cast off-center... which causes the shellwall to be noticeably thicker on one side of the shell than the opposite side. So, for example, a 9" shell can produce some 1.6", 1.7" and 1.8"-thick frags. In the other photo attached below, note that the cavity's bottom shellwall is a lot thinner than at the right and left upper sidewalls.
Regards,
Pete G.
Recent Posts