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I'm going to begin machining my beer can mortar sometime next week. I am using the plans that CU Cannon posted on this site, and am using 4140 steel.

I have a couple questions:

What grade powder do most of you use when shooting a beer can mortar, and how much powder? I'm planning on shooting ONLY beer / soda cans and the heaviest weight of my projectiles will be whatever they weigh (I haven't made any yet) when filled with cement. Of course I will shoot blanks, the short 8 oz. cans and probably cans filled with water.

What are some good starter loads for a newbie to use?

Thanks in advance !
 

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Powder: suggest starting with something slow for safety: Fg or cannon grade, perhaps FFg.

The charge - calucalted by bore, size/shape of powder chamber. Need to know that up front.

DD will have some good comments about charges as well with reference to The More Complete Cannoneer.

I have a HRS beer-can caliber mortar with a powder chamber that is tapered. Generally use FFg. On some mortars (4140 with 1+" thick walls AT THE THINNEST) I'll use FFFg. I consider them to be at least well overbuilt.
 

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excerpt from: THE MORE COMPLETE CANNONEER compiled Agreeably to the Regulations of the War Department as published in "Artillery Drill" by George Patten, 1861 and Containing Other Observations on Antique Cannon By M.C. Switlik with selected excerpts from other artillery manuals


Powder

"Type B blasting powder is made with sodium nitrate instead of postassium nitrate and produces more residue and very unpredicatable results when fired in cannon"

"Thanks to a growing demand, the primary U.S. source of black powder now markets a 'cannon' granulation, much more appropriate for use in cannons over two-inch caliber and under four-inch caliber"

Never use anthing finer than FG. "Recent research has demonstrated it's potential for producing very high pressures and, if it must be used, charges must be carefully controlled and kept to a minimum." "The other granualtions are never to be used for for projectile firing in cannon."

"The finest powders (FFFg and FFFFg) can only be used in artillery ignitors and primers ect."

"An alternative to Sporting grades of black powder is Type A blasting" "If available 2FA and 1FA granualtions can be used. The 2FA is very similar to cannon grade. 1FA is much coarser and should be considered if projectiles are to fired in bores larger than 4 inch However, the 1FA is usually to coarse for bores in the 2 inch to 3 inch range where light charges are used. "

I can not urge you strongly enough to acquire and read THE MORE COMPLETE CANNONEER on this subject of what powder to use.

Switlik clearly states "Do not use granulation finer than 1 F in any Cannon". He does not differentiate between Full scale and small scale guns in that statement. He supports his warning with information on pressure gun test made in the 80's and reported at length in the Muzzleloading Artilleryman.
 

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OK ..... I give ..... Where can I get a copy of this book? None show up on eBay or Amazon. Please let me know ....
 

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Get it direct from the publisher.

Moderators: you might add the above link to the sources sticky.
 

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There have been several recent references to pressure tests made by Matt Switlik back in the '80's. I stumbled over a restatement of those tests today. See The Continental Line and read down through the article for the numbers.

I think the references to "grains per pound" are talking about powder particles, not grain weight, as there are 7000 grains weight per pound by definition.
 

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Hmmm...

In my 1.156" bore cannon, I have always used FFg for blanks and Fg for live rounds.

The FFg gives a slightly louder report than an equal volume of Fg. I have fired dozens of FFg blanks loads and have encountered no problems.

This is a CNC-machined steel barrel (1045 according to the manufacturer) and has proven to be very strong.

Not sure if I should start worrying?


(BTW: I have a copy of The More Complete Cannoneer on order.)
 

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"Not sure if I should start worrying?" What is the outside diameter of your barrel in the vicinity of the breech?
 

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GGaskill said:
There have been several recent references to pressure tests made by Matt Switlik back in the '80's. I stumbled over a restatement of those tests today. See The Continental Line and read down through the article for the numbers.
......


I was impressed by the MEASURED velocity and pressure in the 3" ordnance rifle - while the pressure was much more with the finer powder the VELOCITIES were right-much the SAME. I wonder if that holds true for mortars (with much shorter barrels and less opportunity to completely burn the powder)?



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My guess is that the blackpowder is burning in the barrel and not out side even in a mortar, especally with a projectile in front of it.

If it were smokeless powder it might not all burn in the barrel.

Load you barrel with a charge of powder no wad and no ball. See if any get blown on out. Black just burns to fast. That's why it's an explosive and not a propellant like smokeless
 

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GGaskill said:
"Not sure if I should start worrying?" What is the outside diameter of your barrel in the vicinity of the breech?

I was sorta kidding about the "worring" part. It has had ample opportunity to come unglued, and has not done so (yet).


But since you asked, here are some specifics:


The barrel measures 2.732" diameter at the breech.
The smallest point, behind the muzzle flare, measures 1.812" diameter.
The bore is 1.156" diameter.

Using these dimensions, I get a wall thickness of .788" at the breech and .328" at the thinnest point near the muzzle.

Using a rod to gauge the depth of the bore, I estimate a minimum thickness of about 3/8" behind the breechface. The barrel is solid and drilled, there is no breech plug.

The CNC-machined barrel is advertised as: "Gun Steel (1045 Certified)"


I've been using 500 grains of FFg as a salute load. I have fired dozens of these blanks with no ill effect.

The barrel has withstood several firings with 300 grains of Fg behind a five-ounce ball. I don't use this load anymore, not because I'm worried about the barrel, because of the recoil. I don't want to damage the carriage that I put so much work into. Normal live fire now is 225-250 grains of Fg, depending on where I'm shooting.
 

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Double D said:
My guess is that the blackpowder is burning in the barrel and not out side even in a mortar, especally with a projectile in front of it.

If it were smokeless powder it might not all burn in the barrel.

Load you barrel with a charge of powder no wad and no ball. See if any get blown on out. Black just burns to fast. That's why it's an explosive and not a propellant like smokeless

I do know that there is a point of adding whatever flavor of powder that there is just more smoke and flame with no increase in velocity (distance). That leads me to believe that there is a function of the amount of powder to the length/volume of the bore where the effectiveness tops out. Pressure is another issue.
 

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Switlik says that changing grades of powder just increases pressure not velocity based on his pressure tests. He relates it to grain size. It takes longer for one granule Cannon grade to be consumed than one granule of FFFFG

I have had a conflict in my mind about the effects of this on velocity based on my field results.

Recent testing of the 6PDr mortar showed that 500 grs. of Cannon sent the 6 PDr ball just over 100 yards. 500 grs. of FG sent the 6PDr ball just over 200 yards. If changing the powder grade only results in higher pressure and no change in velocity, how could it be that the ball went further with the smaller grade?

Yesterday doing some testing I found 30 grs of Cannon will send a golf ball about 40 yards. 30 grs. Fg will send the ball about 70 yards. FFG sent the ball out in the hay field and I will have to wait until the hay is cut to see how far the ball went.

These test seem to contradict what Switlik is trying to tell us. The answer just dawned on me. Switlik is working with weight. My loads were by Volume. I may have been loading 500 grs by volume in the 6PDR, but the The Fg weighed more than the Cannon grade. More powder, more velocity.

With that in mind we should be able to reverse engineer our loads and get the same results. So if you have been using a volume measure to load your gun, you need to weigh the charge it throws on a scale. Then use that same weight of 1F or Cannon grade in your gun. The results should be the same at a lower safer pressure.

Speaking of Powder I added Back Creek Gun Shop's[/color] new website to the resource list yesterday.
 

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Do I remember correctly that the 3" ordnance rifle rifled? He was also using a substantial charge. That to me means plenty of resistance that would mean good combustion. We generally shoot things with goodly amounts of windage.

I know that with my 4.5" mortar that Pyrodex doesn't work well unless mixed with a little real black powder and that with the soda-pop bottle mortar two rounds give enough back pressure to get some really decent range (ahem! maybe too much range).
 

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That's true, but the base of the projectile expands to grip the rifling upon firing. From a gas pressure loss perspective, it has no windage.
 

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The lack of windage or windage would only affect the total amount of pressure in the given gun. It would not change the fact that finer grades of black generate higher pressures in the given cannon.

Switliks warning about not using smaller than Fg applies across the board to all cannons full scale and small scale, smooth bore and and rifled he makes no exception. For those that seal the bore like the Parrots and Ordnance rifles the warning should be well heeded. Now I do take exception to the small bore portion of this. Below 1 inch the cannons are nothing more than short barrelled rifles and FFG might be more appropriate.

He also warns that the rule of 2 ozs. maximum charge for per inch of bore diameter with bores of 2 inches or larger applies to loads using projectiles that do not exceed the the weight of the original slug. Heavier slugs require lighter charges. Use cast lead and lighten the charge.
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I would use Fg in bores (or chambers) from 1.5" to .5"; below that FFg. But charge weight is more important than granulation in small bores. I safely use FFFg in my percussion revolvers with their relatively thin cylinder walls but the charge is 28 grains and the ball weight is 138 grains (.44 cal.)

It is my opinion that charge weight and shot weight are the primary concerns with granulation as a secondary one.
 

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GGaskill said:
.... It is my opinion that charge weight and shot weight are the primary concerns with granulation as a secondary one.
I'm not sure that I could rank order them, but it is significant that modern materials are a) stronger and b) more uniform. Perhaps more ductile and less brittle as well.
 
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