So, if you have, for example, 1907 Gun Tech, which allow's you to research 12''/50, 14''/45, and 15''/40, can you research howitzers that are larger than that? For example, can you research a 17'' howitzer, with a barrel that is the same length as the 15''/40, with that tech level? The French banana defense moniter brought up that question in my mind.
I think in determining such a thing, we could go by muzzle energy. Take the ME of an existing gun you have already developed. If the MV of the howitzer is not more than two moves away on the gun tech table it should be ok.
So for instance, a 17"L35 howitzer would have an ME of about 6870 lb.ft.(sq)/s(sq). A 15"L40 naval gun has an ME of about 5200. 6870 is less than the ME of the 18"L40 which is the same gun tech as the 15"L40, but is more than two spaces away on the table. So you'll need to develop some intermediate caliber before you get there. If you have the next up gun tech though, you can probably do it in one jump to a gun with equivalent ME to the 16"L45 on the table.
Then a 17''L30, then? I'll use Biggun to go figure it out...I just wanted to know if it was possible using the tech, and all. On this subject, shouldn't the guns count as 15'' guns with super-heavy shells in the report, since SS2 doesn't account for caliber?
17"L30 would mean 5895.6 lbft(sq)/s(sq). I think that would be an acceptable jump with the given tech.
As far as weight: we don't really account for caliber anywhere, since we use SS2. I have no idea what the relative weight of our figurative 17"L30 would be compared to a 15"L40. To be useful, the howitzer would have to be fireable at a higher elevation, which is going to mean the mount itself might weigh more than expected, for instance. So while the gun weights themselves might have been equivalent, my guess is the heavier weight of higher elevation, higher stressed loading gear, etc. would come close to evening things out.
And I think for consistency and simplicities sake, in almost all cases it's best to use the actual gun diameter in SS. It won't be 100% accurate, but the way SS calculates gun weight based on diameter almost always isn't all that accurate either.
On a similar note, can a 12''/40 be rebuilt into a 6''/80? So I can build the Explosive Phillopino, whoops, look at the time ;D