Letter Stamp
Brent -
There is much debate, and by inference, some disagreement over what many of the letter stamps signify on the various projectiles manufactured within the Confederacy. In this case, there is near universal agreement that a "G" stamp signifies that the projectile was produced in or near Selma, Alabama, and was purchased by (in this case because of the size) the CS Army. The practice was to contract for the castings and to have them delivered to the army arsenal there where they would be inspected, loaded, fused (in the case of the Bormanns) and packed for shipment. I have documentation from one such supplier indicating that the fee for tapping the raw casting for the fuse and the underplug was $0.35 per projectile.
There are other "letters" also attributed to Selma's numerous foundries, and certainly those to the north along the upper Cahaba ("Cahawba" in period writings) River basin - the source for virtually all of the iron, coal, and limestone used by the CS west of the Chattahoochee River after the losses of the iron, coal, and limestone deposits of western Tennessee by early 1862. Pete George is the best source for this one, but others are certainly knowlegable as well. A photo could add to our knowledge on this subject.