Just .50 caliber.
The "Davenport" formula is 11.5 grains per cubic inch of barrel.
To find the cubic inch, you first determine the diameter of the bore, divide it by two to get the radius, and then multiply the radius times itself( squaring the radius), and then multiply that number times PI( 3.1416) to get the area. of the bore. I multiple that times the 11.5 to get that coefficienct for each caliber. Then its simple to multiply that coefficient times the various barrel lengths to complete the formula and get the total powder for the cubic inches of barrel. You have to scratch your memory, unless you are a math person, or engineer, to remember the formula you learned in high school, or Jr. High, I suspect these days, to determine the area, and then cube of a circle/cylinder. Area of a circle it PiR squared. Then you determine the length of the cylinder( bore) and multiply that coefficent times the length, to get the cubic space, and then multiply that number times 11.5 grain, to get the max. charge of powder the barrel will burn.
Since the length of barrel various from one gun to the next, and even within models made by the same manufacturer, its easier to do it my way. I have a table I set up for most of the common caliber sizes, that gives me the max. powder charge in 2 inch increments from 28 to 44 inches. That covers most of the rifles mentioned here. When someone has a 46, 48, or 24 inch barrel, I use the coefficient number I have recorded for each caliber to make the process a short one using a pocket calculator.
Between my brother and I, we have tested this formula on a half dozen guns of different barrel lengths, and bore diameters, using a chronograph. In addition, Phil Quaglino, who gave my brother the formula to share with me, and all of you, has tested the formula on hundreds of guns he has built over the years. Phil holds several National ML rifle records at Friendship, in addition to several Pistol records.
As I have stated before, he got the formula from Nathan Merrill, a Past President, and founding member of the NMLRA, who knew Charles Davenport, the late Chief of Naval Ordinance during both WWI and WWII, and an NMLRA member. Since WWII, the use of cannon, and black powder has diminished, and most of the firepower on naval warships today come from rockets, and gatling guns. The huge cannon barrels and their car-sized shells have gone the way of all good things, with the Missouri being decommissioned about 10 years ago. There may be a few destroyer class ships armed with 5 inch guns, but those will be the last of the cannon mounted war ships in our naval fleet.
I only hope that the Navy is not making a mistake. I just saw a piece on international piracy in the Indian, and Pacific Oceans, and apparently there is also piracy going on in the carribean sea. Those 30 and 40 mm gatling guns are impressive weapons, but they have no where near the range that the cannons have, much less the accuracy at those longer ranges.