Cohorn Mortar soft report

[sundog]

Hummm I dont seem to be getting the 4th of July sound I thought I would get.
I bought a beautiufully made Cohorn golf ball mortar. I started with 50 grains of 1F and a wad of newspaper....poof, switched to 3F poof.
Then I weent to using golf balls. 50 grains launched the golf ball a good distance but no BANG so I tried 100 grains. Well the golf ball vanished, simply flew out of sight but still no boom or at least not the sound I was hopeing for.
Any suggestyions on getting a boom out of it especially without using a golf ball.
I am used to shooting black powder and all I can think of is I need to jam in a really tight wad of newspaper but I simply dont know.
Thank you sundog

 

[faw3]

I had one bigger , real life size and 1/2. I could get window breaking Booms by packing just paper in, nice and tight (not in a bind and not a ton of it just tight,I would think for yours ram a 1/2 paper owel down with no ball first and your 50 grs 1f and see if that sounds right to you! :rotf: (the 1/2 size of mine and 3 sheets of news paper can blow your ears out if your to close..10 to 15 feet. Good Luck and someone with one of those will be on to help ya I'm sure. Fred :hatsoff:

 

[broadarrow]

Hi Sundog, have you tried patching in a wooden Sabot? We tried a damp cloth patch under a wooden sabot and it gave us a decent sound as opposed to using a dry cloth patch which seemed to give a slighty more muffled sound, see how you go, Regards, Broadarrow

 

[TheDoubleD]

Mortars don't bang, they go wompf.

Just remember all that stuff you are cramming down the bore become projectiles when fired.

 

[mazo kid]

This is just a guess on my part, but maybe it has to do with relatively large bore size vs. short length? I know my Trade guns don't have the "crack" that my rifles do with the same charge of powder, more of a "boom".

 

[broadarrow]

Most groups who operate a mortar, cannon or Howitzer have a "no go" zone in front of the piece regardless of whether or not it is live or blank fire as DD stated anything in the barrel becomes a projectile when the piece is fired granted it is harder to get a "bang" as opposed to a "foof" with a mortar, but we use a loosely patched wooden sabot and find that upon firing that they have a tendency to tumble and rarely fly more than 50 yards inside our much larger exclusion zone with a 150gr. 2FFG load, granted you will get a better report out of a similar size cannon with the same size load and we have only been able to work it up to only about a loud rifle shot sound, I only gave a suggestion as to what we have found, Regards, Broadarrow

 

[63mini]

A #22 natural cork can be used. But, as stated before it becomes a projetile.

 

[laffingman67]

This is probly real foolish of me to say. But, The one I built I used 300gr of 1f with a sod wad. this produduced a pretty good thump. Mind, that this mortar was machined from solid 4140, NO THREADED BREACH!! But I talk too much :yakyak:

 

[GunneyG]

What is the wall thickness of the mortar? That pretty much determines what kind of load it can safely use.

 

[Alden]

I have the same problem... My actual-size F&I era repro. coehorn has a 2 3/4" bore, a proper 1 1/8" chamber, and uses 300 grains of Schuetzen Reenactor blackpowder in rammed tissue-paper cartridges but still makes the same similar dull "whump" w/a big cloud of smoke. I do not put anything down the bore due to related-organizational sentiments -- articles on top of powder down the bore come out really fast and hot. And when I fire the mortar next to a three-pounder cannon with the same bore it is embarrassing by comparison. But the mortar is basically a low-pressure burning of a small pile of powder that s/go poof (unfortunately) vs. the 4 oz. (1,750 gr.!) high-velocity developing explosion from the gun.

Still, the examples cited support these rule-of-thumb observations...

For a given charge, the tighter the bore and more tightly packed, the louder the report. .50 Pennsylvania rifles are louder than .69 Charlevilles which are in turn louder than .75 Bess'. Fired bullet loads are louder than paper stuffed shots which are in turn louder than free-poured powder. Mountains of powder rammed down a long tube go "boom" and molehills of powder in a cup go "whomp."

So, safely, put more powder in and/or put a little something on top of the charge to at least ensure the charge is not completely loose becasue you simply can't change the size of your piece.

Alden

 

[David Teague]

Hello All,

My 3/4 scale Cohorn goes "Cough" when live fired with 160 grains of 1F.

It's the Cohorn's big brother "Mr field piece" that goes "Boom" with either a blank charge or live fire.

Cheers,

David

 

[Zoar]

50 grains under a gulf ball just sounds embarrassingly light.

I shoot 45 grains in a Harper's Ferry 12 inch barreled pistol with a measly .58 diameter.

I would up the powder considerably and if you are using tightly packed paper wad I can't see how even 180 - 200 grains could do any harm to a mortor barrel...

 

[paulvallandigham]

Keep the powder charge between 100-150 grains. No more. use dry newspaper packed on top of the powder, then set newspaper- not dripping, of course- packed on top of the dry. The dry protects the powder charge from fouling. Finally, put the golf ball on top of the wet newspaper. You will get a good roar, and excellent distance for that golf ball.

I learned all this working with the same problems, only at first using blank charges, in a British Light 6 pound field piece. The owner began using 1 lb of powder per shot!!! :shocked2: because that is what the original cannon specs called for! We ended up reducing it to 1/4 pound of powder( saved money) and 3/4 pound by volume of ordinary flour, to give the same " roar " and smoke that 1 lb. of powder produced. The flour acted as a " load " helping the powder charge to burn more completely, and reach higher pressure than if it were fired without the flour.

CAUTION: The 6 pounder had a 1/4" thick liner in the cast steel barrel. The Liner was rated to take all the pressure we could created loading the whole barrel with powder and two cannon balls. Work up to this kind of thing, and be nicer to cast iron barrels without liners.