No the lvl 120 guns are gun set only for sbb/bb6 all bb6s for that matter have there own gun set that comes with the ship that can not be removed from the ship at all. well you can't change the R slots but you can change t slots to what ever gun will fit them.
It was done like that most likely to keep bb5s who had bigger R slots then there bb6s from useing the same guns as the bb6 for example a monty could mount the guns of a nebby giveing it the best fire power in the game over takeing all other ships in damage out put. 2nd from the trop with the trip 16s if i'm not mistaken

th for fast respond

Still i wonder how it is possible some lion 2 shoot longer instead of some other lion 2.
I have tested the 100 and the 110 guns, and see almost no range diff.
But no worry i almost have the queen