The drawing is for a MODEL U.S. 1844 Ten Inch Seacoast Mortar. The bore size of 1.75 inch is CO-INCIDENTAL with the size of a Golf Ball, and a stack of four golf balls painted black can be used for display purposes. A GOOGLE search of the Internet should show a lot of these and the BASE for the Mortar can be made quite easily.
It should be pointed out that there is NO hole for a fuze indicated on the plans, and if anyone makes a similar MODEL of this Mortar, and intends on firing it, they are on their own responsibility as they and they alone are responsible for the materials used, and workmanship. If you make a MODEL with the intention of firing it, then YOU ARE ON YOUR OWN. I have my own 2000 aquare food building with a large metal lathe, milling machines, shapers, and welding equipment, and am a Certified Welder, but please do not ask me to make one of these for you.
For MY MODEL, I used a four inch diameter, eight inch long, billet of STEEL. I drilled the hole for the Trunions first, then inserted a blank piece of round stock into the hole, and ground it down to the contour of the four inch barrel. This way, the barrel can be turned in the lathe, then the "plug" pushed out after machining, thus giving a clean Trunion hole. I did not put on the "lifting lug on top of the barrel" or the reinforcements where the trunions meet the body.
IMPORTANT NOTE: The diameter of the body is 3.9838 and NOT 4.9838 as the drawing shows. Another mistake is the 12.3738 dimension near the powder chamber..... This was copied a long time ago from an Internet website, and is not my drawing. The outside dimensions are not critical to four decimal places, but bore and powder chamber dimensions should be followed.
The round stock used for the Trunions is welded in place and the weld ground down to match the contour of the Mortar.