GURPSよろず

Gunslinger
see p. B58
As the Basic Set suggests, the GM may allow low-tech versions of this advantage that cover muscle-powered weapons. Here’s an example suitable for mythic samurai, fantasy Elves, and green-clad English bandits.

Heroic Archer
20 points
You can perform amazing feats with any weapon that uses the Bow skill. When you Attack or All-Out Attack with a bow, you may add its Accuracy bonus to skill without taking an Aim maneuver. If you do Aim, you get +1 after one second or +2 after two or more seconds, in addition to Acc.
When you Move and Attack, you don’t get your bow’s Acc bonus but may ignore its Bulk penalty. Ignore the extra -1 or -2 to skill for a Flying Attack (p. 107) or an Acrobatic Attack (p. 107), too. This lets you shoot at full skill even while running, jumping, sliding down banisters, etc.
You can also disregard Bulk in close combat (see Weapons for Close Combat, p. B391). You never get an Acc bonus there but you do shoot at full skill. This makes the Close Combat technique (p. 69) redundant for you.
You can use Quick-Shooting Bows (pp. 119-120) to improve your rate of fire when you Move and Attack as well as when you Attack or All-Out Attack. Regardless of your maneuver, halve the -6 to skill for this stunt. On an Attack or All-Out Attack, add Acc to your attack roll but not to the skill roll to ready your bow hastily. Similarly, halve the penalty to shoot two arrows at once using Dual-Weapon Attack (p. 83); DWA (Bow) defaults to Bow-2 for you, not Bow-4.
Finally, when you use Fast-Draw (Arrow), total all applicable penalties from Multiple Fast-Draw (p. 103), Fast-Draw from Odd Positions (pp. 103-104), and Move and Attack (p. 107), halve the sum, and round in your favor.
You can combine Heroic Archer with any Weapon Master specialty that covers bows. This gives you the damage bonus for Weapon Master and all of the above benefits – and makes the quick-shooting penalty a mere -1!