Copy-pasting this from old forum.
Gunslinger Guide WIP
This guide is still a work in progress. Please mind the mess.
What is Gunslinger?
Gunslinger is one of the many playable talents offered in Mabinogi. It is also one of the more difficult to play.
What stats factor into Gunslinger?
Strength(STR) and Intelligence(INT) factor into your overall performance with Gunslinger in terms of damage.
Every 5 STR adds 1 point to the player's Max Damage. Every 6 STR adds 1 point to the player's Min Damage. ex: 30 STR would add a total of 6 to Max, and 5 to Min.
Every 5 INT adds 1 point to the player's Max Damage. Every 6 STR adds 1 point to the player's Min Damage. ex: 30 INT would add a total of 6 to Max, 5 to Min.
Due to this, Gunslinger is not a preferred choice for beginners, although it is an option, nonetheless.
If you really want to make Gunslinger a long-term goal, then you should begin with Close Combat, Lance Combat, Mage, and Cleric talents, as those will provide you with STR and INT. Working on Music skills like Composing and Musical Knowledge also offer a significant boost in INT, for relatively little AP.
What makes each gun different?
Each gun has its own focus. For example, DowraSE, while not boasting the highest base damage, is one of the faster choices, and also has the biggest clip size, both before and after upgrades. TaunesMkII, on the other hand, is slower, and suffers from a smaller clip size, but makes up for it by having higher base damage. The base guns (Zeder II and Meriel PE), both offer a bit of balance, and are preferred for beginners.
The two newest guns, Sun Road Colt and Sun Prophet Colt, boast higher min, max, balance, and crit chance than most of the other guns, but suffer from the fact that they cannot be Special Upgraded, along with only one Upgrade path. The guns also work as L-Rods, which are used for Exploration on the Iria Continent, making them useful for Explorers who constantly find themselves switching weapons to fight anything they come across while exploring.
The final two guns, Dowra's Golden Gun and Black Star, boast the highest base stats of their respective normal counterparts (Dowra SE and Taunes MkII, respectively.) However, they cannot be upgraded at all, nor can they be Enchanted.
The Zeder II can be bought from NPCs. Meriel PE, Dowra SE, Taunes MkII, Sun Road Colt, and Sun Prophet Colt must either be made through the Hillwen Engineering Life skill, or bought from other players. The Black Sun and Dowra's Golden Gun are only obtainable through Gachapon, but can be bought from other players.
What about bullets? What's their mechanics?
Bullets provide their own bonuses, mainly in the form of providing additional Min and Max Damage. Each bullet will fill up a gun once (so, a stack of 100 bullets would completely refill a gun 100 times, regardless of clip size; one refill per bullet.) In order from lowest boost to highest:
Training Mana Bullet (lowest, +5 Min/Max) -> Mana Bullet (+10 Min/Max) -> High-Density Mana Bullet (+20 Min/Max) -> Suntouched Mana Bullets (highest, +30 Min/Max). Training bullets can be bought from NPCs; all other bulets must either be made through the Magic Craft Life skill, or purchased from other players.
What about the skills?
Normal Attack: Normal Attack refers to attacking an enemy without using any skills. This "Action" is used by all classes, but how the skill deals damage depends on the weapon. With Dual Guns, each Normal Attack will unload two bullets, hitting the enemy twice (with training requirements for Dual Gun Mastery, each normal attack trains the respective training requirement twice: once for each bullet.)
Dual Gun Mastery: the main mastery skill for the Gunslinger class. Each rank boosts the Min and Max damage values while having Guns equipped, and also provides extra HP.
Reload: When your gun runs out of ammo, this skill will refill your weapon's chamber. Each rank reduces the time it takes to reload your gun. You are forced into a motionless stance while the skill is active, and being attacked will cancel the skill.
Flash Launcher: A single-target skill. Activation cost is two bullets. This skill is essentially Gunslinger's version of Close Combat's Smash skill: you launch one single, powerful blow against the opponent, with damage amplified, and also ignores the Defense skill. Each rank increases the skill's damage multiplier.
Shooting Rush: One of the Area of Effect skills of the Gunslinger Talent. Activation Cost is 8 bullets. Any monsters within the range of the attack will have a red arrow appear above their heads. The attack will launch you forward, as your enemies are knocked back by the rush of bullets. Each rank improves the damage dealt, the max range, and increases the max number of targets.
Bullet Storm: Another Area of Effect skill. Activation cost is 4 bullets per target. Like Shooting Rush, all applicable targets will have a red arrow appear above their head. Unlike Shooting Rush, your character stands still as they unleash a hail of bullets, pushing enemies back. If the first bullet launched deals a critical hit, all bullets will land as a critical hit. Each rank improves the max number of targets and max range.
Grapple Shot; A single-target skill. Activation cost is 2 bullets. Upon selecting a target, the bullet will launch, and you will "Grapple" onto your opponent, pulling yourself towards them, while stunning them. Each rank increases max distance and damage. This skill is often coupled with Flash Launcher, as the stun from Grapple Shot allows you a window to load and execute Flash Launcher, with Grapple Shot also taking care of the distance issue.
Bullet Slide: A single target skill. Activation cost is 2 bullets. This skill, when used causes you to unleash a stream of bullets at the target, while pushing yourself back. Great for creating distance between you and any enemies who happen to get too close to you. Each rank increases damage multiplier.
Way of the Gun: A self buff skill. Costs no bullets to activate. When activated, your your gun chamber is instantly filled, and you are blessed with infinite ammo. Also, all normal attacks with Guns land critical hits. Once the skill ends, your gun chamber will be empty, and, in most cases, Reload will automatically activate (usually if you spam-click during the skill's final moments.) Each rank increases the skill's duration. If you switch weapons or weapon slots while the skill is active, it will immediately cancel itself.
Thanks to Marith for suggestions, and info I missed regarding benefits provided by bullets.
Suggestions are greatly welcomed.