I have played only Colorado and Tenny...
but i have tested triples 14' MK7 and compared largely with Dual 16' MK2.
the result was that 14' Mk7 are just like a "bad version" of a PBB gun... they have same angle but can't penetrate quite well anything above BB3... so even if you can hit once or twice you will land only a 50 to 70% of your 12 shell salvo (and this with good gunners) making something like 6 to 12k of damage only in rare times you will hit a "blockshot" but mostly against big BB's that your gun's can't really hurt much.
The main advantage is that low angle its easy to master and the bad spread will help while learning to aim, as you might be hitting with at least 1 or 2 shells even if you aimed bad.
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When using Dual 16' Mk2 your spread will be decent in no-time so when you hit something big, you will be hitting with 70 to 100% of your 8 shell salvo, making something like 13 to 18k damage. Decent for a BB2, and even hurting BB5.
Besides angle 40' will allow u to carry AP, that will help you A LOT against UK AW BB... i have sinked a lot of UK BB3 & BB4 with the colo, and this was thanks to the AP capabilitys of those baby-monsters 16' guns. Also angle 40 its not a bad angle to handle (if you grinded your CA's you have to be awared thanks to that 41º 8').
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you are free to test it for yourself, but remember, if you pick tenny you can use both 14 and 16, but if you pick Penny you will be stucked with 14'.
For the rest Tenny its a little worst than Colorado (wich is best US BB2) in every aspect, its slower, can't use the "lolsetup" of triples 16 Mk3 D, and can only carry 3 binds of ammo for Dual 16', has a tinny less durability and less auto AA, the only real advantage is their gun arcs, But turning force its slower than Colo...
Despite all of that Tenny it's still a good BB2 (one of the best in the game) and you should play Tenny just like a Colo. with dual 16...
Penny, while i think its not a bad BB2 at all, it remains inferior in terms of firepower and spread, and in the end this is the main goal of any US BB... the big punch