Boom J
Here is the information on this mortar as was provided to me by its creator who was offering it for sale several years ago. He only made two like this, one for himself and has never fired it because he didn’t want to change its nice new appearance, and a second one for his close personal friend, now deceased, who fired it often.
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“This is very nice solid bronze mortar with all brass hardware on the teak wood mortar bed.
The mortar tube was machined from a 65 lb. piece of solid 4 1/2" diam. bar stock, the trunnion is 1 5/8" diam., reduced to 1 1/2" at the cheeks. The back of the mortar tube was machined to accept the trunnion as a press fit and was then TIG welded into place & hand ground to finish. The bottom of the tube has a reduced size chamber of 1" diam. The tube is 12" overall length and 4.355" od.
The mortar bed or carriage is built from 1 3/4" solid teak wood and is 24" long and 8" from cheek to cheek. The tie bolts are 1/2" diam. brass and run all the way through the bed from side to side. the trunnion straps are brass formed by a purpose built die jig, The elevation assy. is also solid brass.
The materials cost for the bronze tube alone was close to $300 at surplus prices and the brass hardware added another $100 to the cost. The tube is
aluminium bronze which is much tougher and harder to cut than brass. It shines up like brass but requires carbide tools to cut and took two days to cut the bore.
The bore is sized for concrete filled soda or beer cans with .025" windage. A nice charge is a full scoop made from 1/2 of a .50 cal BMG shell which I will include and comes to about 140 grains of 2f powder.
The complete mortar weighs 54 lbs.”