Shell & Case thickness

[Rookie]

The Ordnance manual of 1861 provides thicknesses for the walls of both 12-pounder shell (0.66 - 0.74, "true" = 0.70 inch) and spherical case (0.425 - 0.475, "true" = 0.45 inch). For 6-pounder ammunition, only the thickness of spherical case (0.335 - 0.385, "true" = 0.36 inch) is given. Does anyone know whether there was a standard thickness for 6-pounder shell (presumably thicker than case). I have a collection of spherical shell and case fragments that can be broken down into 6- and 12-pounder frags based on estimated full diameter. I would now like to try to differentiate between case and shell on the basis of the thickness of the fragments. Six-pounder frags that I have range in average thickness between 0.31 and 0.45 inches and I wondering whether those between 0.4 and 0.45 might not be from shell. 12-pounder frags measure between 0.33 and 0.78" in thickness. I'm assuming the ones greater than 0.66 or so are more likely to be from shell while the thinner ones are likely from case.
Of course, I'm recognizing that corrosion more likely than not is giving me somewhat larger thickness measurements. I've also been told that CS shell (and case?) might have been thinner than the US standard.
Thanks in advance for any help and insight.

 

[PCGeorge]

Hello, Rookie ...and, welcome to the Civil War Bullet Forum.

Since you're new here, I think I should mention my qualifications for answering your questions. For about 35 years, my specialty-area in relics has been civil war Artillery projectiles (and fuzes). I co-authored a lengthy book about them. I check this forum a couple of times a week to help answer questions like yours.

Logic indicates the shellwall thickness of 6-pounder caliber Common-Shell would be approximately .60-inch, plus-or-minus a couple of hundredths.

Based on my decades of very closely examining frags from CS-made shells, and sawed-in-half specimens of CS-made shells, I do not think their shellwall was specified (by the CS Ordnance Department) to be any thinner or thicker than the yankee counterpart of that caliber of projectile.

That being said... please keep in mind that the thickness of any shell fragment will depend on the shell's powder-cavity having been properly "centered" during the ironcasting process. An off-center powder-cavity causes the shellwall to be thicker on one side of the shell than on the opposite side. To see what I mean, view the attached photo of a Confederate 3-inch caliber Broun shell.

Also based on decades of close observation, I can say that CS-made shells have an off-center powder-cavity more often than yankee-made shells ...due to less-skilled ironcasting in many privately-owned Southern foundries. I should mention that a "significantly" off-center cavity can cause the shell's weight-distribution to be out -of-balance (like happens with modern automobile tires), which can result in wobbly flight when that shell gets fired. Therefore, part of an Artillery Ordnance Inspector's job was to check projectiles (at the ironfoundry or arsenal) for casting-errors such as an off-center cavity, and to reject any he detected. Unfortunately, such inspection was not always done "rigorously."

I hope this information is helpful.

Regards,
Pete [P.C. George]

 

[Rookie]

P.C. George,
Thanks for the welcome and thanks for your insights. I was beginning to wonder (given the Ordnance Manual's silence) whether 6-lb common shell actually existed (though I've seen published photos of whole examples w/ missing fuse and presumably contents, I've never seen an intact 6-lb common shell cross-sectioned). Your thought that 6-lb common shell walls should be about 0.6 inch in thickness makes all my examples case, which I can easily live with. I also appreciate your comments regarding reliability of thickness measurements. I am already hesitant to use these figures given the effects of corrosion, but pointing out the potential for variation in thickness even from one part of shell to another due to production difficulties had not occured to me.
Thanks again.
Steve