Dude,
I have played for 13 years and was captain of Shades of grey 2 and Shades of Grey, I have used 2 Mags, 3 cockers, 2 shockers and currently run an Impy.
I suggest you dont worry about shooting loads of paint first, find a gun that suits you primarily weight, accuracy and reliabilty.
All of the players including myself will give you advice based on what we know.
The things we dont know are how old, how big and how strong you are. Are you a static player or a Back player that pushes up?
All of these have relevance, for example what use is 15 pots on your back if you cannot stand upright without discomfort?
I suggest that most back player shoot a lot of paint to provide cover for the front players, volume has no use on its own, a steady rate of accurate fire and revisiting the target at regular intervals is much more efficient
Combine this with good observation and good calls to your front players and if you all do it right the game will be over quickly and you will carry ten of the fifteen pots back in every time.
Personally I take out seven pots, and regularly shoot five, however given the chance I like to get in the thick of it and push up the field.
Ask you friends, borrow their guns and try them, but above all be sure you know what you want before you buy it.
There is nothing more demoralising than a player in your team who is dissatisfied with their gun, if you are not confident with your gun - you are not a confident player. How can you then expect your front players to believe in you?
Go to the retailers and ask to try their guns, if they want to sell it they will let you try it.
I hope this helps
Marky H