I have an idea to make a Barbarian Gunslinger who specializes in big booms.
The firearm FAQ states:
Specifically in the case of firearms, a Medium character can’t use a two-handed firearm sized for a Large or larger creature, and a Small character can’t use a two-handed firearm sized for a Medium or larger creature
However, the Titan Mauler syas:
Massive Weapons (Ex): At 3rd level, a titan mauler becomes skilled in the use of massive weapons looted from her titanic foes. She can use two-handed weapons meant for creatures one size category larger, but the penalty for doing so is increased by 4. However, the attack roll penalty for using weapons too large for her size is reduced by 1, and this reduction increases by 1 for every three levels beyond 3rd (to a minimum of 0). This ability replaces trap sense.
Would A Titan Mauler Gunslinger be able to use a large 2-handed musket, bypassing the standard rules regarding large firearms.