Like archery, too many are worried about speed. If you don't have accuracy, you don't have $#@*!
I have always like big bores with short barrels. If you need more speed, get a longer barrel.
But if you can pick up some speed and accuracy with just a breech style, I am all for that!
I would have to build the parabolic design in two pieces, and jam them together.
I understand accuracy.
The load mentioned above for the DK rifle (1900 fps) has shot <6" at 200 yards with a tang sight in testing when the wind is calm. If the (any) breeze comes up its strings horizontally. I had to be shooting just after first light to beat the wind for 5-10 shots then pack up and leave.
The velocity also gives it a 130 yard or so point blank range. Where I live this comes in handy.
AND finally in my experience loads in the 1700-1900 fps range will out shoot light loads. This based on people competing in 60 yard rest matches.
I don't know that this table is exactly precise, but its pretty darned close.
If you live in the east and shoot critters at pistol range distances flat trajectory is less important.
This is a 50 yard group one shot with a lead ball, one with a W-W alloy ball and one a lead ball in a paper cartridge unpatched (thanks for the info Daryl).
This is a .662 ball at 1600fps. It gives a flat trajectory though not as flat as the 54. It still is a good 120 yard gun if sighted right. I did not go faster for 3 reasons. 1. The load shoots well. 2. velocity was adequate for ANY animal I would shoot with a 16 bore and 3. It was the point of diminishing returns. Adding more powder did not give a commensurate increase in velocity.
Dan