I recently ordered a coehorn mortar from Hern Iron Works of Coeur d'Alene Idaho as featured here...

[url]http://www.hernironworks.com/cannons.html[/url]

I have searched around the internet looking for load data and I am not coming up with much in the way of specific information.  What I have found seem to place maximum load at 400-600 gr. of either ffg or fffg black powder.  This is (obviously) a wide range of load and I need something more specific.

Thank you for your time.

Going to Philly?   If so, be sure to fire a few rounds before you go, so that you get the ranging.  You want the first round to be "Target..Fire for effect"

Dunno what you are talking about, but I am interested.

btt

Zippy-

You didn't say wether you just wanted to go "boom" or really launch a 24 pound shell.  Look for American Civil War artillery renacting groups on the web for info on "blank" loads.  A 10th of a pound (700 grains) seems pretty small to me, even for a blank in that size tube - but I am NOT an artillery guy.

Good luck,
bjt

I am not an artillery guy but I would think you would want to use Fg not doubble or triple F. Double F is usually used in rifles above .50 cal and thriple F is used in rifles smaller than .50 cal and FFFFg is used in the flash pan for flint locks.

If the max load you have seen is 400 to 600 grains then I would work up it. BP is not a real efficient propellant and does not create the high chamber pressures of smokeless powders.

You can safely load BP down to levels that are just enough to barely get the ball out of the barrel.

I would start with a load of around 300 grains just to see what happens. From there I would work up in increments of 50 grains to 500 grains and then 20 grains from 500 to 600. I would probably not go beyond the max recomended. You should be able to get a max from the manufacturer, most muzzleloading rifle maker provide this information.

Also remember the finer the grain of the powder the less you have to use for the same effect. In other words you can use less of FFFg than you would of FFg. This is because finer grain BP is more efficient burning.

Have Fun!!

Rusty

Be VERY careful about firing that mortar.  The manufacturer makes no warranty regarding using it for firing projectiles and the casting has not been proof tested.

I know for field guns the powder load was typically about a pound of 1F.  I would suggest working up the load slowly and ensuring you fire it from substantial cover in case the casting ruptures, shooting fragments everywhere.

Did ya ? You know ...





drill the hole yet ?

Well, let's see...

Nope, no hole yet.  I dont even have it yet.  Just trying to gather data in anticipation.  I should have it in the next few weeks.

As far as the disclaimer that Hern posts...they do that to avoid liability.  Incidentally, Hern Iron Works is the supplier of Coehorn mortars to Dixie Gun Works, as featured in their catalog.  I am sure most of you are familiar with their operation.  The only difference between the one Hern sells and Dixie's is that Dixie drills the vent hole, which, in Hern's opinion, lays the liability on Dixie for converting the iron cylinder into a firearm.  Dixie, btw, recommends, per their 2002 catalog, "1-2 oz. of powder."  No mention is made to what grade of blackpowder to use...and their range...1-2 oz. (437.5-875gr.) is much too vague for me to rely on.  I am looking for safety tolerances as well as range estimates for various loads for a given projectile.

To be honest, my main interest in acquring such an item is twofold.  One, is just the "coolness factor" of owning a piece of artillery with a relatively large bore, as well as a desire to make some noise.  Lots of noise.  I just might send a few projectiles a-flyin, but I am more concerned with making noise.  BAH-BOOM!

I'll never grow up.

Thank you for your time.