Cannonball?

[Dubbs]

Hi,

I found this at an estate sale. It's a perfectly spherical iron ball measuring ~2.9 inches in diameter and weighing 3lbs 5oz. It has patina and evidence of past pitting. From the dimensions it seems to match U.S. Army Ordnance specs for 3" grape shot, though there's only an average given for weight. Using their formulas it seems to be close to what it should be, given wartime quality control. The organizer thought it might be a milling ball, but admitted he didn't really know and didn't want to speculate. I picked it up because the manufacture seemed too clean to be an ore crusher (also it would be an extremely small example) and the composition seems to be the same as a few pieces of authenticated canister shot I have in my collection (similar patina, similar mottling, similar casting texture), and for $10 I was willing to gamble. If you all have any input I'd sure appreciate it.

Thanks,

Dubbs

 

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[TheCannonballGuy]

I'm glad to see you appear to already be familiar with the US Ordnance Department's diameter-&-weight specifications for spherical artillery projectiles (cannon balls, grapeshot balls, and canister-ammo balls).
www.civilwarartillery.com/shottables.htm
The data for 32-pounder caliber grapeshot balls says:
diameter 2.86-to-2.90"
weight 3.15 pounds (about 3 pounds 2 ounces) - which is the maximum weight, not an average.

Unfortunately, your 2.90" ball is three ounces heavier than it should be for a 2.90" ball made of cast-iron. Therefore, your ball must be made of steel... which is a heavier alloy than simple cast-iron. Being made of steel disqualifies it from being a pre-20th-Century artillery ball. The Ordnance Manual says all artillery balls are to be made of cast-iron or lead.

Historical artillery projectiles are my specialty area of relic study. I co-wrote the book "Field Artillery Projectiles Of The American Civil War." I also co-wrote a detailed educational article telling how to authenticate actual cannonballs from the many kinds of imposters, here:
SolidShotEssentialsMod
That being said... it is not my intention to sound like Mr. Know-It-All in my analysis of your metal ball. I dislike having to give people a disappointing appraisal.

 

[Bruce R]

Being in the coal business, I can say that's not from a ball mill, those are chrome plated and super hard, they generally shatter before they'd wear. Also, they don't have mold lines like your piece obviously does. I don't know if it's a cannon ball or not, but there were many different sizes of cannon throughout history and it may not be domestic either.

 

[Dubbs]

So, I sent a text to a friend (who's an engineer) and he's going to look at it tomorrow to determine what it's made of. The calculated density is 7.65g/cm^3, in the range for soft cast iron (6.8-7.8g/cm^3, mild steel has a density of 7.85g/cm^3).

Edit: So, I got to reading the 1862 Ordnance Manual, and found some interesting information. According to the authors, solid shot is expected to exceed the figures given, in fact it can't be rejected for being too heavy, only too light. As this is based on primary source research, I'd say there's some serious misinformation floating around out there.

Here's the excerpt (p.38): "The average weight of the shot is deduced from that of three parcels of 20 to 50 each, taken indiscriminately from the pile: some of those which appear to be the smallest should be also weighed, and they are rejected if they fall short of the weight expressed by their calibre more than one thirty-second part. They almost invariably exceed that weight."

That is, the weights in the table are in fact minimum weights, not maximums as in a modern handloading book.


A bit of self disclosure: I'm a post-grad researcher who dabbles in archeology. Mostly regarding the rather contentious issue of proto-Judaism, specifically early artifacts and inscriptions insinuating that in at least one form of early worship, Yahweh had a wife.

 

[Bruce R]

This thread is marked as solved, are we missing a post here? I'm not seeing anything but continued speculation.

 

[TheCannonballGuy]

The 1861 Ordnance Manual says that (at that time) the Specific Gravity of cast-iron used in solid (not hollow) artillery balls was 7.000 -- which is different from the Specific Gravity of most of the modern versions of iron. Check the end of the chart on page 37 in the Ordnance Manual, viewable for free online at the bottom of the webpage at
www.civilwarartillery.com/shottables.htm

That statement in the Manual indicates your ball is not made of the pre-20th-Century cast-iron used in artillery balls.

 

[Bruce R]

So I was right? Not solved ?

 

[Dubbs]

The SG value given refers to the relative purity of the alloy. As the percentage of impurities (carbon, silicon, sulfur, etc.) increases, the specific gravity and ductility/maleability decrease as well. Thus, a sample with a SG of 6.800 would be harder and more brittle than a sample with a SG>7.0 increasing the wear and tear on field pieces (not to mention making them more prone to catastrophic failure) which had very soft iron or bronze barrels. The figure of SG=7.00 is supposed to be the safe standard, any iron softer than that is safe to use, anything harder/more impure, not so much.

A parallel can be drawn between firing modern ammunition utilizing copper-washed steel jackets. It's safe to use because it is softer than the barrel material. Firing ammunition with a hardened tool steel jacket would in the best scenario cause excessive wear and in the woust, possibly kill you. Metallurgy had not advanced far enough to produce safe munitions of consistent quality, necessitating the complicated proofing process (visually inspecting,weighing, measuring, dropping, etc.). Hard (i.e. impure) cast iron is extremely hard, so much so that it's occasionally used as backhoe bucket teeth, not something you wand to put in the barrel of a gun without a sabot.

Additionally, this specification ensures that the foundries the government was contracting with was not either shorting them or passing off inferior quality goods. It functions as a garantee that if a foundry sold the army 1000 8lb cannonballs, the government was getting at least 7750lbs of projectiles if no single shot weighs is less than 1/32nd off from the gauge weight, as the specs demand.

Really, the book is so straightforward had I read it first, I'd never have even posted here. If it looks like a duck, has the sprue marks of a duck, and falls within the specs of a duck, it's a duck.

 

[Tnmountains]

The SG value given refers to the relative purity of the alloy. As the percentage of impurities (carbon, silicon, sulfur, etc.) increases, the specific gravity and ductility/maleability decrease as well. Thus, a sample with a SG of 6.800 would be harder and more brittle than a sample with a SG>7.0 increasing the wear and tear on field pieces (not to mention making them more prone to catastrophic failure) which had very soft iron or bronze barrels. The figure of SG=7.00 is supposed to be the safe standard, any iron softer than that is safe to use, anything harder/more impure, not so much.

A parallel can be drawn between firing modern ammunition utilizing copper-washed steel jackets. It's safe to use because it is softer than the barrel material. Firing ammunition with a hardened tool steel jacket would in the best scenario cause excessive wear and in the woust, possibly kill you. Metallurgy had not advanced far enough to produce safe munitions of consistent quality, necessitating the complicated proofing process (visually inspecting,weighing, measuring, dropping, etc.). Hard (i.e. impure) cast iron is extremely hard, so much so that it's occasionally used as backhoe bucket teeth, not something you wand to put in the barrel of a gun without a sabot.

Additionally, this specification ensures that the foundries the government was contracting with was not either shorting them or passing off inferior quality goods. It functions as a garantee that if a foundry sold the army 1000 8lb cannonballs, the government was getting at least 7750lbs of projectiles if no single shot weighs is less than 1/32nd off from the gauge weight, as the specs demand.

Really, the book is so straightforward had I read it first, I'd never have even posted here. If it looks like a duck, has the sprue marks of a duck, and falls within the specs of a duck, it's a duck.

We are lucky to have the "Cannon Ball guy" here who is our go to Author and authority on ordinance.We are glad that you stopped in and hope you find this forum a useful tool in your interests.

 

[tamrock]

Being in the coal business, I can say that's not from a ball mill, those are chrome plated and super hard, they generally shatter before they'd wear. Also, they don't have mold lines like your piece obviously does. I don't know if it's a cannon ball or not, but there were many different sizes of cannon throughout history and it may not be domestic either.

IDK Bruce, being in the hard rock mining biz for 39 years I've seen rail car loads of mill grind balls and none were chrome plated and many have visible casting seems.

 

[Bruce R]

Just telling what I've seen used here, I helped dismantle one, transport it, and set it up again, the balls were plated. We dumped them out on the floor and scoop-shoveled them by hand into barrels.

 

[tamrock]

Just telling what I've seen used here, I helped dismantle one, transport it, and set it up again, the balls were plated. We dumped them out on the floor and scoop-shoveled them by hand into barrels.

Sure, I believe there are different kinds and sizes of mill balls used for different kinds of materials to grind. I'm just saying I've seen mill balls that are just like this item. I was asked once to come up with a special air chipper chisel to clean out the seam joints between the mill liners to be changed out at the Henderson Molybdenum mine here in Colorado when I worked at a company called Brunner & Lay. That's a big ball mill and I got in it to watch how this special thin blade tools worked out. I read in some mining history book, when the ball mill was first developed for the early mining years they used some kind of hard stone mill balls from France before they made better cheaper steel.

 

[Bruce R]

I can believe the stone ball thing, Here we use the ball mill to pulverize anthracite, it goes in one end as coal and comes out the other as dust with the consistency of talcum powder. When a bagger breaks the stuff is knee deep on the floor and it flows away from you like water when you try to shovel it. By the way, I was gonna post a stone ball so here it is. Any idea what it's for? I think it's marble.View attachment 1309425View attachment 1309426