Considering he has dodge twelve, getting an equivalent parry score verses a musket would require Parry Missile Weapons 28 (28/2-2=12). Remember, parrying a bullet is a -5 penalty to parry, and parry is Skill/2+3 for Skill/2-2 when trying to parry a bullet.
Getting a skill to 28 is prohibitively expensive, on the order of 76 points for a DX 10 character, a price that barely drops with increased DX or levels of Enhanced Parry/Combat Reflexes.
So I propose making PMW a technique:
Parry Missile Weapons
Default: Cannot be used at unimproved default, Unarmed or Melee Weapon Skill -5
Prerequisites: Unarmed or Melee Weapon Skill, cannot exceed prerequisite skill +4.
This Technique allows a character to parry thrown or missile weapons with a ready melee weapon. If you are wearing wristbands or gloves with DR 2+ or have at least this much natural DR, you can also parry with your hands. Your Parry Score is (Technique Skill/2+3), rounded down- based on this technique, not the underlying combat skill that this defaults to.
Modifiers: +4 vs large thrown weapons (axes, spears), +2 to parry small thrown weapons (knives, shuriken), no modifier to parry arrows, -2 to parry smaller low-tech missiles (crossbow bolts, sling stones, blowpipe dates). Enhanced Time Sense and other appropriate advantages (e.g., Precognition) allow you to parry bullets at -5.
With this technique, a fighter with ETS can pay ten points to be able to parry bullets at a -3 to parry. Those without ETS will still enjoy much better parries against large thrown weapons (parry +4), arrows (parry +2), and smaller low-tech missiles (no modifier to parry).
For many characters with decent statistics, dodge will likely remain a better defensive option, and this technique really only benefits characters with high skill with their weapon to begin with- although stacking it with Combat Reflexes and Enhanced Parry certainly makes it even more powerful.