Loading & Firing Questions

[mac_hunter]

I have some questions about a video I watched on YouTube, maybe some of you gents on here can help me out. The video is titled "Gunner Tanya Shoots the Mortar." The mortar is an original 1819 British 4.5" bronze Coehorn Mortar.

At 3:20 into the video, they show their loading sequence. They don't show the bore getting wormed and sponged however, somewhere in the video the narrator mentions that this is done between every shot and the shots are fired one every 15 minutes.

QUESTIONS:

1st - BP is loaded loose, poured directly into the mortar, no foil bag. Is this a bad idea for this particular piece of artillery/should a foil bag be used?

2nd - They are using 3Fg. For a mortar that size, wouldn't one want to used Cannon or 1Fg or 2Fg as a last resort? (They are lobbing 4.5" candlepin bowling balls)

3rd - They patch the ball with a tee-shirt rag, similar to patching a .490 caliber round ball in a .50 caliber Hawkin rifle. Isn't there supposed to be some windage room between the projectile and the interior wall of the barrel, like 1/40th of the bore diameter or whatever that formula comes out to?

4th - Wouldn't a small over powder wad of cardboard or similar material sufice, if sealing the powder chamber was a concern, without impeading the windage of the projectile? Or should wads be avoided?

5th - They do seal the fuze vent with a thumb but with the fuze already in place before driving the patched ball into place. Wouldn't putting the fuze into the powder charge through the vent after pricking the powder bag be the last step, just before lighing?

6th - They drive the patched ball down the tube with a plastic covered hammer. Shouldn't the ball easily slide into the tube with little to no persuasion? See question 3.

I also have some saftey issues later on in the video (at 5:30) when you can cleary see that someone, although off to the side quite a bit, is in front of the firing line when the mortar goes off.

Thanks for any inputs that I'm sure you all will post.

[Rickk]

my versions of answers to your questions:

1 - somewhat normal and common for a full sized mortar. It is pretty easy to get hands and cleaning equipment down in there and insure there are no embers, so it should be relatively safe.

2 - 3F doesn't sound too cool

3 - Assuming the charge is light enough, and the powder course enough that chamber pressures are kept low, patching by itself isn't hurting anything, but putting one's body over the barrel to work on getting the ball in is standing directly in front of a loaded gun - not really a smart thing to do. An unpatched ball with windage would just drop down the tube and there would be no need to work on the business end. A tightly patched ball will increse pressures... most of those of us that shoot blanks in sturdy microcannons know that.

4 - a simple, loose over-powder card isn't going to hurt anthing. If it helps shot to shot consistancy I would be all for it - I use them myself in my mortar to keep the powder where it is supposed to be.  Without it, ignition becomes irratic - especially with lighter loads. I'm not trying to seal the bore up, just keep the powder in place.

5 - I'm not sure why they would do it that way.

6 - Chamber pressures would go up. Charges woudl have to be adjusted accordingly. They would be working in a dangerous location while they are doing this. Personally, I stand behind my mortar, slide the ball over the muzzle and drop it.My hand is well out of the way by the time it gets to the bottom. I'm wearing a welders glove on that hand as well.  From behind the gun I use a U-Shaped rammer to make sure it got to the bottom, but I'm not really ramming - just measuring for proper ball placement.

[Double D]

QUESTIONS:

1st - BP is loaded loose, poured directly into the mortar, no foil bag. Is this a bad idea for this particular piece of artillery/should a foil bag be used?

This is correct.  But it requires some safety equipment. Welders gauntlet, safty glasses,  Also Some states may require the cartridge.

2nd - They are using 3Fg. For a mortar that size, wouldn't one want to used Cannon or 1Fg or 2Fg as a last resort? (They are lobbing 4.5" candlepin bowling balls)

1FG nothing smaller

3rd - They patch the ball with a tee-shirt rag, similar to patching a .490 caliber round ball in a .50 caliber Hawkin rifle. Isn't there supposed to be some windage room between the projectile and the interior wall of the barrel, like 1/40th of the bore diameter or whatever that formula comes out to?

1/40th is a rule of thumb, not a hard and fast rule and is for quidance.  The patch was a bad thing to do, and add to it they were were using FFFg powder.

4th - Wouldn't a small over powder wad of cardboard or similar material sufice, if sealing the powder chamber was a concern, without impeading the windage of the projectile? Or should wads be avoided?

Wad really isn't needed unless you are using charges large enough that you need to retain them in the powder chamber some how.

5th - They do seal the fuze vent with a thumb but with the fuze already in place before driving the patched ball into place. Wouldn't putting the fuze into the powder charge through the vent after pricking the powder bag be the last step, just before lighing?

Yep you got it right. The whole ide of thumbing the vent is to stop air rushing creating a draft.  Vent should be thumbed with a leather thumbstall. Last thing is inserting the fuse.

6th - They drive the patched ball down the tube with a plastic covered hammer. Shouldn't the ball easily slide into the tube with little to no persuasion? See question 3.

Yep!

I also have some saftey issues later on in the video (at 5:30) when you can cleary see that someone, although off to the side quite a bit, is in front of the firing line when the mortar goes off.

They have people wandering all over the place all through the video.    At one point you can see a table to the right rear of the mortar and the color of the objects sitting on the table strongly suggest Schuetzen black powder cans.

Does anyone think the mortar is real or a repro? 

Their safety techniques weren't up to snuff, but they were trying.  And they had a young girl shooting and enjoyiing it and that is important. 

[Rickk]

Massachusetts requires a foil wrapped, plastic bag containing powder charge.

I'm not sure about N-SSA, but AAA only requires foil wrapped charges for cannons, not mortars. They still require a pre-measured charge... you can't be up there pouring out of a powder can. However, the charge does not seem to be required to be in a foil container, I believe the pre-measured charge can be poured thru a funnel into the powder chamber. It doesn't have to be, but it can be.

In Massachusetts it has to be in the plastic and foil container to be compliant with the regulations (which were developed with guidance from a group that arn't all that involved with, and tend to look down on mortars)

I believe the significant difference between powder charge preparation between cannons and mortars is that cannons always want the same amount, whereas in mortars the charge could be adjusted to get a different point of impact.

[Artilleryman]

One good reason not to patch the ball would be that if the charge failed for some reason, the ball will roll out when you tip the mortar up (after a suitable length of time after the failure of the charge).  The N-SSA requires pre-measured charges in clearly marked containters that indicated the difference between the main charge and boost charges of 1Fg powder which can be poured in loose.  It also does not allow patched balls for the reason mentioned above.  Stopping the vent with a thumbstall is not required because the sponging or cleaning process is different than with a cannon, however the vent is to be cleared between shots.  Gloves and gauntlets are required to be used by the #1 cannoneer who does the loading.  Primers are inserted last and a vent shield put in place.

[Cat Whisperer]

I understand the motivation for the FFFg and patching, although I do not endorse it.

My bowling ball of 4.6" weighs only 2-3 lbs compared to the much heavier iron or zinc.  This results in poor ignition of slower powder.  Patching was also likely to be used for the same reason - to increase pressure to get good ignition.

[Rickk]

One thing we don't know is the amount of powder. If it is dinky, that might make much of this all this OK (although a poor learning example to extrapolate from).

Even putting the fuse in first makes sense if the charge is really light, as the ball may partially block the vent hole after it is in place and make fuse insertion difficult. I have had that happen myself, and had to add about 1/4 inch of corrogated cardboard over the powder (inside an aluminum foil cartridge) with light loads to raise the ball up a bit. My vent is angled towards the breech, so if it clears the ball, it WILL penetrate the powder bag.

I have stayed with cannon grade, even with really light loads, because I figure it will fill more and raise the ball higher for a given muzzle velocity.

one last thing... I have no sub-chamber... that makes small charge shooting more difficult.

[GGaskill]

I always put the fuze/ignitor in first when loading a mortar with loose powder.  I don't want the insertion process to ignite the charge, even if unlikely to do so.

[mac_hunter]

Rickk- I'm not sure that 2.5 oz of bp would be considered dinky.

To all- thanks for the replies. It appears that the majority so far has agreed with my findings. Even on here though, there is varying degree of opinion. My reason for asking all of those questions is because I'm getting a mortar made of the same diameter. I want to make sure that I've got the procedures down before I ever put powder and fire to the thing.

[Rickk]

nope... 2.5 ounces of BP isn't dinky

[Double D]

Tim revisit Switlk pg 105. Recall that in the pressure testing Switlik found in service charges of equivalant sizes,  Fg gave 40% higher operating pressure than Cannon grade for the same velocity. That continues expoentially down the scale.  That's also why the applications that use the finer grades also use less.

I have seen you state this issue of better ignition with the faster powder and lighter projectiles before.  I have never encountered this phenomenon myself with black powder.  Where I have seen it is loading smokeless cartridges.   What I have seen with the heavier grades of black powder Cannon and  FG vs FFG is less energetic ignition.  The boom isn't as big!   

[mac_hunter]

I've got another question somewhat related to this. In the limited search (most from the internet) for likely projectiles to fire from my soon to exist mortar, I came across Shot Put balls. They come in varying diameters. I was looking at the 114-115mm range, made of cast iron or machined from mild steel, weighing 12 pounds. I really would like to see a full scale 4.5" tube fire a full weight ball with a max service charge of powder, for range purposes. I'm still toying with the idea of candlepin bowling balls and 114mm bocce balls. I've even thought about casting my own zinc balls. Problem with that is I'd need a mold made and I have no other casting equipment to even get started. Having trouble finding zinc on the net too.

[Rickk]

I seem to recall that one of the sponsors was toying with the idea of making a mold to cast hollow lead speers. (generally two halfves that get soldered togther). I'm pretty sure it is Wes (Powder Keg). He definitely can make one that makes solid balls, as I have one of his.

All you need for equipment besides a mold is a propane burner (of the turkey fryer variety), a big cast iron frying pan, a ladle, and the mandatory safety equipment (glasses, welding gloves). Lead can usually be scronged for cheap or free if you look hard enough.

[mac_hunter]

I'm seriously considering getting a mould made whereas I would be able to cast any number of projectiles for my mortar. My only concern is the cost for such a large mould. Upon completion, the mortar and bed will have cost me a hefty sum alone. Then again when I think about it, the one time cost of a mould and, oh say, enough zinc to cast 12-14 balls would be cheaper in the long run (and more fun) then paying exorbitant fees for any of the "ammo" that can be found "pre-made" on the internet. As far as using lead, I was going to try and avoid that for all the reasons stated higher up on this thread about causing excess pressure. I believe that I've also been advised on this forum that mortars, when used for there intended purposes, originally fired spherical case-shot (hollow balls filled with both musket balls and a bursting charge) and/or spherical shells (hollow balls filled with just a bursting charge). Both of which where considerably lighter then the actual rating of 12 pounds given my particular mortar due to its bore diameter of 4.62" or projectile diameter of 4.52" (which when cast solid from cast iron would weight 12.25 pounds). One idea I had to lighten the weight of solid cast zinc balls (to around 9 or 10 pounds) was to drill a series of holes in them similar to finger holes in a standard size bowling ball. Thereby lightening the projectiles and giving them a bit of an audible flare, similar to the whistling sound that a full size bowling ball makes when it is lobbed from a mortar that can fire such projectile sizes. Any coments?

[Rickk]

A hollow lead sphere, made with a hollow mold, would make lighter projectiles than a solid mold will make. You would have to work out the numbers for the ID and OD given the intended casting material when you order it to get the weight you want. For lead, you can solder the halves together. I'm not sure what you would do with Zinc to stick them together.

Be careful of Zinc fumes if you go that way... it is way more nasty than lead. Some have even theorized that feeling bad after extensive lead casting is actually a reaction not to the lead, but to minute amounts of zinc impurities in their lead sources.

Some here have cast projectiles out of aluminum.

I guess it will largely depend on your casting material sources. For me, I can get all the free lead I want, so I like lead.

I havn't needed to go to a hollow mold yet because even a solid ball goes far enough for me with rediculously light loads. The one day that I tried a concrete filled pipe weighing 1#, iinstead of a 2# lead ball, the concrete filled pipe went way farther than I wanted. My charges  for shooting 2# projectiles at 100 yards are so small they are on the border of being erratic, so for me the heavy solid lead ball  is here to stay.

[Double D]

Mac,

You could always buy precast 12PDR shot from Paulsons.

Check the Cannon list for suppliers from who you can buy zinc.  I got my first batch of Ebay it was being sold as surplus anodes.  Scrap yards will have scrap zinc.  Some new wheelweights are now zinc instead of lead.  Carburators are made of zinc look for scrpped out old carb's in the junk yard or scrap yard or maybe at a carb rebuild shop. Look on Google for item made of zinc and the visit shop that might repair or make those articles.

Last month on one of the boards (I ain't telling my source) one of teh guys said he was given a 50 lb ingot of zinc and wanted to know what to do with it.  i told him to send it to me and he did for postage.

Make others aware you are looking for Zinc and it will show up.  

Here is my zinc melting system.



Weed burner, cast iron pot and a Wes Pilley 6 PDR mould.  Thinking about sending the 50 lb Ingot down to Wes so he can have it to R&D mould handles.

[Don Krag]

I have about 1200 lbs of pure lead and close to 200 lbs of aluminum. At a planned bore of 5.5", a lead ball would be a seriously heavy ball! I had thought about lead balls with an aluminum core. I figured sandmolding a softball, then casting aluminum, then using this as a core in a lead mold. I had also thought about using clay balls as a core...anyon ever done this? Is there an "ideal" mass or mass:bore ratio for mortars? If doing the competitions the heavier balls would obiously drift less, but require larger powder loads. Is there a "standard" ball-type/charge for large mortars?

For cannons as opposd to mortars, how does solid aluminum fly? Being more dense than pure zinc, it should get better ballistics out at farther ranges. At 200 yds, using a 2" ball is there that much noticeable difference, or does the faster short-range velocity still dominate at 200 yrds? I know when duck hunting there was considerable differences between steel and lead shot at different ranges (especially out pst 40 yards)...I was curious how this is when using the larger projectiles of a cannon.

On a similar note...why do the cannon rules say "never fire solid steel projectiles". Is this due to there bouncing and traveling long distances, or something else? If proper windage is used, jamming in the barrel shouldn't be an issue. I use mill balls (legend mine supply, Reno, NV) as projectiles for my 1.1 and 1.2" gonnes and they work great.

[GGaskill]

Actually zinc is about 2.5 times as dense as aluminum (418 lbs/cu ft vs. 169). 

The original shells were hollow so a bursting charge could be put inside; that would require something that could be broken up to make the casting core.  A bi-metal shot (Al core with PB or Zn shell) is an interesting idea since hollowness is not a requirement.  Al-Pb would work well since the melting points are quite different; Zn-Al would be more difficult since the melting points are much closer.  Clay would work but should be baked completely dry so you don't get a steam explosion when pouring the hot metal around it.  You can check for dryness by weighing the clay core at intervals during the drying; when the weight remains the same after an additional period in the oven, no more water is leaving.

Shells weigh between 2/3 and 3/4 of the weight of a solid shot of a given diameter, so they will have a lower ballistic coefficient than a solid shot.  At short range, the increased velocity will be advantageous but the denser shot will work better at long range.

Aluminum shot would work and would give lesser pressure and recoil.  If you are shooting at relatively short ranges, they should be fine.  The main problem is the higher melting point which would make casting more difficult and require steel moulds, although they could be sand cast with a lot more work.  Zinc is almost exactly the same density as cast iron and melts at a lower temperature than aluminum (but higher than lead) so it makes a good substitute for cast iron shells and shot.

The "never fire solid steel projectiles" rule is probably from a concern about the sparking of steel on steel in the presence of black powder.  I think that is virtually impossible in the context of loading a muzzle loading cannon.

[Artilleryman]

I have used aluminum balls in a 12 pdr mortar.  One of the main problems is that they are affected by the wind.  We fired some at 200 yards with a cross wind and ended up having to point at least 30 yards to the left of the stake to get it to land near the stake.  Firing shell weight projectiles is the best bet.

[GGaskill]

Nelco Athletics is a place you can buy shot puts but they have a high minimum order so you probably will want to find others to split the order with.  There was a post discussing this but I can't find it with the Search being disabled.  Well, now I found it. 

http://www.graybeardoutdoors.com/smf/index.php/topic,92776.msg567270.html

[mac_hunter]

So let me see if I'm interpreting you all correctly. Aluminum is too light due to wind deflection but could be used as a solid. Lead is too heavy and for my personal use will be avoided for safety reasons. Solid cast iron balls weighing 12 pounds would be ok as would zinc, with zinc being the more economical of the two. From what I've read in an 1863 Ordnance and Gunnery book, cast hollow balls required extensive set-up and equipment to be cast properly in sand. I have no desire to cast hollow balls in the first place even if someone managed to come up with a design for one made from steel. The process just sounds to cumbersome and time consuming for me. I'd rather spend more of my time lobbing projectiles, then casting them and trying to join two halves, etc. I think that I might contact one of the sponsers on this board to see if I can get a steel mould made relatively cheaply and cast solid zinc balls. From there I think I'll experiment with my former idea of lightening them by drilling "finger" holes in them. According to range charts I saw in the same book, a 24 pound Bronze Coehorn Model 1841 fired a 17 pound shell to a distance of 422 yards using 4 ounces of cannon grade BP. I took the same reduction in weight by percentage (roughly 30%) for a 12 pounder and came up with 8.4 pounds for a ball (shell) weight. Does anyone out there think that 3.6 pounds of weight could be removed from a 12 pound 4.52" solid cast zinc ball by drilling 3 "finger" holes in them of about 1/2"-5/8" diameter to a depth of about 1.5"-2" (like a standard bowling ball)? As a side note, with the ball seated over powder, the holes would be positioned on the opposing side of the ball from the powder charge.

[Don Krag]

For some reason I was having a severe brainmelt with the weight of Zinc.  Guess I should have looked at a periodic chart!

I use sand for aluminum, although a steel form would leave a smoother finish. It would get kind of pricey after a while with Al, though. That's where clay came to mind. Mortar mix was another thought. I have a couple burnout furnaces, so drying out mortar or clay balls would be easy enough. Mortar, sand and perlite mixed together would make balls easy to form and easy to dry since that's essentially hommade rammable refractory. I was just trying to think of inexpensive ways to make large balls and cores came to mind since I have quite a bit of lead. I guess I could always make my own extremely-leaded, aluminum-bronze alloy. I've had a few accidental-experimental alloy mixes that might have qualified!

Can balls be easily dug up and remelted/recycled from motar shots, or do they tend to be pretty deep in the ground?


P.S. I think the finger holes would be worth it just for the whistling effect!!!

[Evil Dog]

Would not drilling "finger holes" in the ball have pretty much the same effect as casting voids?  Seems to me that it would cause the ball to be "out of balance"..... if there is such a thing... resulting in erratic flight.  I know that casting voids are not a good thing when it comes to the round ball I use in my flintlock rifles and it just seems logical that the same theory would apply to cannon or mortar ball.  Just a thought to keep in mind.

[Rickk]

I don't know this for a fact, but I was always under the impression that an undrilled bowling ball is made a tad heavy on the size intended to be drilled so that when it gets drilled it will be closer to balanced. The "drill area" on a new ball is marked... they don't just pick a spot and start drilling.

If it matters to a bowling ball, it probably will matter to a cannon ball.

If you are going to have a custom mold made anyway, check with Wes and see if he figured out how to make hollow molds. Then you can use lead, which is way cheaper than anything else.

BTW, if you have 1200 pound of "pure lead"... save it for something else as it is way more valuable than range scrap. I would go with range scrap myself... it is cheaper (often free), harder (you don't need soft for an unpatched smoothbore, and harder may be better for a hollow ball). 

[mac_hunter]

As far as I know, bowling balls (to include house balls) have an inner core that is balanced in a certain way and to a certain side of the ball so that when the holes are drilled in that certain spot, it either assists with putting spin/rotation on the ball or to keep it tracking straight down the lane, once thrown. I could see that if you drilled three holes on one particular side of a solid mortar ball that it would change the center of gravity. I'm not sure how inconsistant the accuracy would be having holes drilled in the mortar ball though. One thing that I do know when it comes to accuracy, whether it is when you shoot a rifle or a bow or throw a baseball or a bowling ball or hit a golf ball at the driving range, is that CONSISTANCY in all the imaginable variables is the most important thing to get repeatable accuracy. That is why I said that with the ball seated over powder, the holes would always be positioned on the opposing side of the ball from the powder. Keeping this variable consistant, at least in my mind, should keep the balls impacting on target fairly accurately. Now as far as the drag effect in flight that having holes in the ball would impart on the trajectory, which effects accuracy, I have no clue. I figure that consistantly following a strictly regimented loading and firing sequence, that the drag effect in flight imparted on the ball with holes would be negligible, thus making for fairly accurate impacts on target. I guess the only way to tell for sure is to wait until I get back from South Korea in late April and get my mortar and run it through some tests to answer these questions.

[Double D]

Yes you are going to recover your shot when you fire your mortar. TO&E for the Mortar shooters at FT. Shenadoah includes a shovel. 

Drill one zinc ball with holes just see what happens.  My guess is it will be a waste of time. Just drop it in the pot and remelt it if it doesn't work.  Same thing when the shot gets beat up just remelt. Zinc won't get beat up as quickly as a lead.

Holes are not going to contribute any thing useful. And getting precise placement is not realistic.  Remember the mortar was basically a grenade launcher.  Close was good enough.

I can also tell you after a while just shooting shot out into space is boring.  Trying to hit a target is fun, espcially when you hit it.

Save the lead for the little bullets.  Large lead balls will raise pressure and generate excessive recoil and break things...I have first hand experience here.

[Don Krag]

I figured a solid lead ball on that scale would be generating some high pressures and generally be a pain to handle. I'll shoot for the weight of a steel ball and try a few things. It'll be a while before I finish the mortar and am worrying about projectiles, though!

I have several other toys in works with much smaller bores to use the lead on. The pure stuff is pretty soft. I planned on alloying to stiffen it up before using it for bullets. It was radiation detection equipment shielding and accellerator shielding in its former life, which requires fairly pure lead. The places I worked with never wanted to deal with the lead removal when decommissioning the equipment. They were always more than happy to let me take it off their hands! One of the things I actually miss about that job!

[Rickk]

pure lead is highly desired by small bore muzzle loader shooters. Before you alloy it, ask around and see if you can swap it for alloyed metal. I would think you could probably swap it  pound for pound for a larger amount of already alloyed metal, as pure lead is rarer and worth more.

In fact, you don't live anywhere near western Massachusetts do you?

[Double D]

For the record, I have 6 PDR Round ball mould for Zinc. It is currently not being used. I can make it available for loan.

It will require security and payment of shipping

[Don Krag]

pure lead is highly desired by small bore muzzle loader shooters. Before you alloy it, ask around and see if you can swap it for alloyed metal. I would think you could probably swap it  pound for pound for a larger amount of already alloyed metal, as pure lead is rarer and worth more.

In fact, you don't live anywhere near western Massachusetts do you?

Hah...nah, I'm down in Central TX. I figured pure lead would load up the bore too much.

If you live near a major university, call up the radiation safety office and ask if they have any liquid scintillation detectors being decommissioned for scrap or if they have any scrap pharmecuetical shipping shields that have been surveyed. They often have to pay to have these removed and are quite willing to give them away. U-Mass and MIT have large research departments. An old LSC unit will have about 300 lbs of pure lead in a configuration that is useless for any other shielding application, so it just gets tossed.