Guns: my 68pdr guns

In early 1999, I had this series that I did where I had a range of guns with the same shot weight. This one is the "68 pdr gun" (5.15in):

D      Shot    Length   Weight    Length     Length      MV
       Weight  in Cal.  of piece  of piece   protruding  
5.15in 68 lbs  25       2.28 tons 10ft-9in   6ft-5ini    1,600 ft/sec
5.15in 68 lbs  30       2.73 tons 12ft-10in  7ft-9in     1,960 ft/sec
5.15in 68 lbs  35       3.19 tons 15ft       9ft         2,200 ft/sec
5.15in 68 lbs  40       3.64 tons 17ft-2in   10ft-4in    2,400 ft/sec
5.15in 68 lbs  45       4.1 tons  19ft-4in   11ft-7in    2,700 ft/sec
5.15in 68 lbs  50       4.55 tons 21ft-5in   12ft-10in   2,850 ft/sec

The idea is to have these available for use in ship designs of various periods.