Late game it is very high damage and very versatile, however i've heard its often hard to start a file as a gunner only due to ammo costs, and non shareable armor.
Some basic tips: Practice some normal lvl 1 shots in an empty zone when you first try it, just so the zooming, aiming, reloading, and shooting comes naturally to you. You can choose to quickly reload the current clip as you ready your gun.
A lot of ammo types have a recommended distance from the target to get the most damage from them. Usually this is about 4-6 rolls away from the target or something. You will know when you hit the right spot when your shots have a larger white flash as they hit. The range stat on your guns will contract or lengthen this minimum distance, and the range it covers.
You will take a lot more damage due to low def armours. Pay attention to your dodging, and be prepared to take hits if you have a shield rather than try a risky dodge. Preferrably dodge it all though, chip damage is pretty big.
pierce shots hit more than once, so try aiming them lengthwise along the smaller monsters to avoid the ammo passing fully through them before it is used up.
Pellet shots are bad for group quests, unless you're careful
If you're working through Offline, Pellet will rip up some of the early quests. It's also quite decent versus Qurupeco - the pouch is a pellet magnet which helps interrupt calls. Also, pretty much guaranteed a beak break.
But definitely agree with working some form if melee too. If only for underwater hunts.
well i was having trouble with qurupeco using SnS just managed to kill him might have a try with bowgun then when i got the hang of aiming etc
If you're confortable with farming Royal Ludroth, I would suggest Ludroth frame / Heavy bowgun barrel / Medium bowgun stock which loads 5 each Pellet 1 and 2. It has one way deviation, which doesn't make any difference since you'll be firing Pellet. Unless you run out of Pellets. Back up ammo is Normal 2. Pellet lv3 fires with recoil, so don't use it. Ludroth gunner comes with Pellet lv 1 up and slots enough to get Pellet All Up giving you 7/7 Pellet 1/2 - but upgrade the frame before working on the armour.
Don't bother too much with aiming. Just point generally in Peco's direction and spam pellets. His beak and pouch are pellet magnets, which is good and bad since his body is a better gun hitzone than his head.
You'll have a tough time breaking wings this way, so Flintstones may be harder for you to get.