-A pistol shot is can be used in melee combat. Shooting an adjacent enemy with the pistol does not provoke opportunity attacks when used in melee combat.

-The Musket can be equipped with a bayonet, allowing its user to wield the firearm, Two-handed, in melee as a spear (Prof +2, Dam 1d8+1). Firing the musket with a bayonet attached reduces proficiency to +2. Add or remove bayonet = minor action)
-A Musket equipped with a bayonet doesn’t break on a roll of 1 when used as a Two- handed spear
-Any small dagger/knife can be used as a bayonet
-Dex used for ranged attacks and Str used for melee attacks (Shooting a pistol as part of a melee attack still uses Dex)

Pistol: One-handed Superior Weapon; Proficency: +3; Damage: 1d10; Range: 15/30; Price: 100 gp; Weight: 3 lb.; Group: Firearms; Properties: Black Powder,
Load standard, Off-Hand, High crit
(Shooting an adjacent enemy with the pistol does not provoke opportunity attacks)

Musket: Two-handed Superior Weapon; Proficiency: +3; Damage: 2d6; Range: 20/40; Price: 300 gp; Weight: 10 lb.; Group: Firearms; Properties: Black Powder,
Load standard, High crit

Blunderbuss: Two-handed Superior Weapon; Proficiency: +3; Damage: 2d6; Range: Close blast 3; Price: 500 gp; Weight: 15 lb.; Group: Firearms; Properties: Black Powder, Load standard, High crit, Brutal 2
(The blunderbuss is considered a basic attack, but may not be used in conjunction with powers. When you attack with the blunderbuss, if your attack roll is higher than you Fortitude defence, you are subject to combat advantage until the end of your next turn due to being thrown off balance)

Firearms Note:
-When firing a, a thick cloud of smoke fills the square where the weapon was fired, providing light obscuration until the end of the firers next turn.
-The noise from a firearm reveals your firing position if hidden.

-A roll of 1 is a misfire, the powder is wasted but the shot is not.

-The weapon itself is useable as a basic melee weapon, and classed as such for purposes of feats and powers with the weapon breaking on a roll of 1.

-For melee combat, Pistol = Club (Prof +2, Dam 1d6) Musket/Blunderbuss = Great club (Prof +2, Dam 2d4)

-All powers requiring a crossbow are also usable with Pistols and Muskets.

-Unlike other weapons, when buying a magical version of a firearm, you must add the original cost of the firearm to the cost of the magical one.

My take would make loading a standard, with a feat available to make it a move.

Make actually firing the weapon a minor action or possibly even an interrupt.

Allow the weapon itself to be useable as a melee weapon, with it breaking on a 1.

I think “load move” would work if you really want to emphasize how slow they were. The main thing, I think, is not to reduce them to less than one attack per round — that’s what makes them either completely useless or an overpowered “alpha strike” and then useless.

Guns aren’t supposed to balance with bows or crossbows. They’re supposed to replace them. I have used this in my game based on Medieval/Fantastic China for a while.

I don’t feel that this makes ranged rangers/ranged rogues particularly unbalanced either. Your average damage goes up certainly, but not really to a degree where it’s treading on the toes of other classes. You’re talking 2-8 damage vs 1-8 damage, and maybe a +2-8 damage every twenty attacks. That’s tiddlywinks. A lucky streak, some good tactics, or more than likely variations in effectiveness due to power selection more than average out the difference.