I broke my can

[John N]

I suffered my first burst soda can while firing a half scale coehern mortar last night using 400 grains of 1FG. All previous shots firing up to 350 grain loads have remained intact. The mortarÂ’s barrel was undamaged. I recorded the shot using a Nikon digital camera taking 3 frames a second and a Canon digital camera in movie mode.

Here is a blow-up picture of the moment of firing as captured by the Nikon (lucky shot):



HereÂ’s the next shot taken by the same camera 0.33 seconds later. Note the flame event is long over



Next are two frames from the movie clip taken 0.07 seconds apart:





In the second shot, you can see the concrete core and the aluminum can have separated (two dark objects towards the top left side of the picture) . The can floated down about 15 feet from the gun. The concrete core sailed out of sight. Here are a couple pictures of the can. The can was facing up in the barrel and the bottom of the can is missing.





Obviously I need to cut back on my load. ItÂ’s interesting that this coehornÂ’s sub-chamber can probably hold 800 grains of powder, but my future beer can shooting will stay at or below 350 grains.

[Double D]

Some of the fellows at Ft Shenadoah were only using 235 grs. to go 100 yds  and that was with a 24 PDR ball.

Do you have any  Idea how far you projectiles go? Are you recovering any.

Half the fun is watching them hit.   I use to launch my slugs into a stock pond.  The geysers were like incredible, right out of an old WWII Black&white war movie.

[Cat Whisperer]

They just don't build them (beer cans) like they used to.

My first mortar was the old style can (Old Style beer worked good too) which is the same diameter as current soup cans. Much more metal.

[John N]

Double D,

I'm guessing300-400 yards out (and tumbling end over end all the way).

I've been shooting into my woods and haven't  recovered any projectiles.

[GGaskill]

I, too, have problems will concrete-filled beer cans as projectiles.  Too much powder and the concrete breaks up upon firing.  My mortar is chambered for about a half ounce of Fg and more than that is too much for the ammo (I need to make a round ball mould and cast some lead balls [this will not be a safety issue as the mortar is more like an 1841 8" mortar than a Coehorn].)

When the cans stay together, I get a bit over 200 yards from them unless they stabilize in flight and fly heavy end forward (I fill only half the can with concrete.)  

My bronze 2 pounder mortar will throw a 2 lb lead sinker 600 yards on a half ounce of Fg.

[guardsgunner]

DD,
   When someone told you that they were only usin 235 gr. in their 24 pdr. , they was funin' ya.
   ord. manual calls for 1.5 oz. or around 650 grs.  I dont know if it is the differnce in the powder then and now but mine takes 835 grs. and usualy runs one line lower the the given ranges on the chart at all the ranges I have fired.

[Double D]

I was looking at the the loading chart on the inside of the lid of the chest from behind the firing line  Ft Shenandoah.  They were firing at 100 yards and the chart was scaled in if I recall right 10 yard increments.  the team i as watching was record ing the effects of every shot in a log book.

I was looking at the chart through my Stiener binoculars with my 56 year old eyes and I was wearing my glasses.  Now don't go telling me my binoculars are bad!  :drink4:

You have the first hand experience and I defer to your expertise.

[Cat Whisperer]

On the flip side of the coin, they could have had very close fitting spheres and gotten quite a bit more range.  Barrel length is a factor as well.

In the process of the golf-ball mortar making contest I will have several that will be right-much similar except for barrel length and bore diameter.  That will shed a little more light - to have very similar mortars except for the variable we wish to measure.

[Cpt Ed]

John N

Have you ever tried the smaller 8-oz cans?  



How far do you think they will fly?

[John N]

Cpt Ed,

No I haven't fired any 8 oz can but I'll be looking for them in the grocery store. Generally speaking, with a given powder charge a half-filled 12 oz can will not achieve the distance of a fully filled can. The half filled cans might stabilize a lot better than a fully filled cans which tends to tumble end-over-end starting right out of the barrel, at least in my mortars.

I want to see how these 8 oz cans behave in flight. A 12 oz can extends to the top of my sleigh mortar's barrel and extends a good inch beyond the mouth of my coehorn barrel. An 8 oz can would drop down further into the barrel.



The smaller 8 oz cans will have a proportionally longer distance to travel in the barrel and might acquire better stabilization. They might exit the barrel later in the powder burn and enjoy more of a "push" out of the barrel instead of a whack.

Has anyone out there tried the smaller cans? I bet they fly several hundred yards. I'll let you know what I achieve after I make up some loads.

[Cat Whisperer]

Her's my experience:  the heavier the projo the longer the distance.  From shooting 16, 20 and 24oz soda pop bottles  the big ones fo much further.  

Barrel length has a big effect as well - longer time of being pushed & attains greater muzzle velocity.  My beer-can mortar (old style cans 1975 vintage) will go 130 meters (it has a barrel 1/4" longer than the can) where a friend's mortar (24" barrel) will go over 400 yards using much less powder, with less noise and smoke too.

Two golf balls at once - first one out of the barrel goes further,

There also is a point where more powder just means more smoke and no further gain in range.

[GGaskill]

No need to waste money on the small cans, just cut a regular can in half.  Easier to get the concrete in, too.  But harder to see in flight.