Mike and Tracy, thanks for the inquiry and interest in my two little shooters. Actually, I bought the mortar tube from Powder Keg, here on the GBO Forums. The mortar base only was purchased from SBR. The chamber is about 1 - 3/8 inch deep and about 7/8 inch wide. These measurements are secured by a rather primative way of measurement. The drink cans (beer/soda) are filled with concrete. To move these projectiles about 100 yards, it takes only 70 grains of cannon grade BP. I have not ventured to move them any further down range - YET!
The little SBR Dahlgren gets the vent cleaned merely by sticking a garden hose down in the muzzle and pressure of the water does a pretty good cleaning of the vent. Then I use some soapy water and brush the devil out of the bore and of course quite a bit will squirt out the vent. The musket cap has been drilled out somewhat to accomodate a plain old pipe cleaner and then doused with a spray oil.
Yes, we did top your 97 degree temp yesterday. Our thermometer, on the sunny side of the house showed about 102. Of course, as you know, the shady side showed around a mere 85 to 90 degrees. Humidity was down real L O W so sitting in the screen house with a couple Miller Genuine Draft cans of brew made the temps almost enjoyable. It's a tough job to have drink all that beer in order to accumulate some more mty beer cans to be converted into projectiles for that mortar.
Enjoy the balance of the 4th of July weekend.
Blaster (Bob down in the far South end of Colorado)