Gun Technology
1885 Primitive (-3)
1895 Dated(-1)
1900 Baseline(0)
1902 Advanced(+1)
1907 Cutting Edge(+3) - was 1910
1911 - was 1915
1915 - was 1920
1921 - was 1925
1928 - was 1930
Gun technology allows to research better and better guns of the same caliber, represented in gun barrel lenght. It also allows switch to larger calibers. Starting from L/30 barrels upto L/60. In the table below, this is represented by the different colors. The numbers are the approximate muzzle energy in million lbs x ft^2/s^2, if someone wants to use ahistorical designs. Although everyone is encouraged to use correspoinding historical guns (preferably UK and German) to spare himself from excessive additional work.
(http://img402.imageshack.us/img402/5320/guntechmi7.png)
You can develop a gun, if
- you have the relevant gun technology (the row)
- you already have a gun design not more than two spaces away (moving up/down and left/right) in the table above. So no big jumps in capability.
The year of gun technologies - when research could be started - was advanced by a few years to allow some historical designs.
1905 -> 1902 ("Advanced")
1910 -> 1907 ("Cutting Edge")
1915 -> 1911
1920 -> 1915
1925 -> 1921
1930 -> 1928
I found a good correlation for muzzle energy (E) as a function of Gun Barrel length (L) and bore diameter (D) for guns of the 1900-1945 period.
ME=0.04 x L x D^3
Where
E is expressed in million lb.ft^2/s^2
L in inches
D in barrel length in caliber
All fantasy weapons should use this correlations.
This correlation can be justified the following. The size of the gun, and thus that of the gun propellant chamber scales as D^3. Also, the longer the barrel, the more propellant can be loaded into the chamber so that it would burn completely.