High Plains Digger wrote:
>He had what seemed to be a 12 pdr (I did not have calipers or scales, next time is different!) that looked
>pretty good but it seemed slightly off round. Can a good hit do that to a ball?
No - a hard impact cannot "smush" a cast-iron object. Unlike wrought-iron, cast-iron isn't flexible/bend-able. Cast iron is brittle ...meaning, it will fracture/shatter instead of merely bend (or, "smush"). ALL cannonballs were cast-iron. If a ball is out-of-round, it definitely is not a cannonball.
>But then, the owner [...] asked "Why would they go to the effort to grind off a mould mark on a mill ball?"
The answer (why) is -- the problem of what is called "Mold-seam Flashing." In that term, "flashing" doesn't mean a bright light. ;-) The term refers to something like the sheet-metal "flashing" used in the Roofing industry. Here's what "Mold-seam Flashing" means. In the metal-casting process, the two halves of the mold MUST be very tightly clamped together, perfectly snugly - because a "loose" or imperfect fit will allow some molten metal to seep into any gap between the mold-halfs. The result of a "loose" fit is that when casting is completed and the mold is opened, the cast metal object will have a razor-blade-like projection (which resembles sheet-metal Roofing flashing) along the mold-seam. The "casting flashing" is ragged and VERY sharp. It can easily injure any person who handles the cast metal object. Also, if not removed, the "flashing" can cause snagging or jamming when the cast object is used for its intended purpose. Therefore, the Manufacturer (Foundry) tends to remove the flashing - usually by grinding it off. (Or by filing, if the cast object is made of a "softer" metal such as brass.)
High Plains Digger also asked:
> I remembered how you said the [cannon] ball must be smooth and round without major imperfections to make
>max use of the [cannon-firing] blast. So Please, how much imperfection can a ball have before it is not acceptable?
>I sure don't want to pay good bucks for a mill ball.
Almost no imperfection was allowed for a cannonball, because it "filled" the bore's width all by itself. However, a LITTLE more imperfection of form was allowed for Canister-balls and Grapeshot balls, because such a ball doesn't "fill the bore."
High Plains Digger already knows the following info, so this part is included for other readers:
The big problem we cannonball collectors face is that there are literally MILLIONS of "round-ish" iron objects which have nothing at all to do with Artillery. In addition to rock-crusher/mill-balls, there are Sports Shot Put balls, machinery counterweight balls, "unusually large" ball-bearings, Ornamental Ironwork balls (such as gatepost-tops), and even early Reproduction cannonballs made for historical monuments.
So, in addition to looking for "imperfections" (such as out-of-roundness, and grinder-marks), we cannonball collectors must keep in mind the fact that Military ammunition was always very carefully manufactured to meet the Ordnance Department's very strict size and weight specifications. If an iron ball doesn't match up within .03-inch and a few ounces of the Ordnance specifications, it is not a cannonball. View the civil war Ordnance Department's specifications (which are the same as Revolutionary War, and 1812-War) at:
http://www.civilwarartillery.com/shottables.htm
Regards,
Pete [P.C. George]
