Generally, you should never need a backup gun in game. However if your primary breaks, its best to have either a quick replacement, usually a rental type like a Tippmann 98 (or your first gun) for the next game.
If you're referring to sidearms, the best pistols are the Tippmann TPX (my preference and the T8. Its really a decision between having co2 in the gun separate from the magazine (tpx) and having the co2 in the magazine (T9/8). This means that you get full use of the co2 in the TPX, but you also may have to load two separate things. Also the TPX magazines are cheaper due to them having no valves or pipes.
no it is not
the worlds strongest shot gun is a mosberg
Miles
The dessert eagle
I guess AKM47
No
ak47
the strongest is MP4
It's the UMP45 silenced. It is an overpowered gun. Or the Intervention or Barrett.
the ry3no
No
it is the strongest gun in the game but needs to charge