Pistols
There are several pistols available in Saints Row 2, for example, the GDHC, the Kobra, the NR4, the Vice 9, the .44 Shepherd and the Stun Gun. Pistols are best used in close combat, as their accuracy and power are dwarfed by some of the more powerful guns available. It will also take enemies longer to recognize you as a threat if you are carrying a pistol, so if you need to approach someone and get a quick kill, a pistol may be your best bet. Pistols can also be dual wielded for double the firepower. The Stun Gun isn't technically a pistol, but it looks like one and it doesn't fall into any other category.
Submachine Guns
Saints Row 2 has three different submachine guns, the GAL-43, the SKR-9 Threat and the T3K Urban. Submachine guns can be dual wielded like pistols and share many of the same advantages and disadvantages with pistols. Submachine guns shine when you need to spray a small area with bullets, as you can empty a clip in just a few seconds.
Shotguns
There are five different shotguns available in "Saints Row 2"---the 12 Gauge, the Tombstone, the XS-2 Ultimax, the Pimp Cane and the AS14 Hammer. Shotguns are extremely deadly at close range, especially when used against a group of people. While a shotgun can kill an enemy in one shot, once you get more than a few yards away they really lose their effectiveness. The shotguns in "Saints Row 2" all fire at different speeds, from slow reloaders like the 12-Gauge to automatic powerhouses like the XS-2.
Assault Rifles
"Saints Row 2" has four different assault rifles, the AR-50 XMAC, the AR-200 SAW, the AR-40 XTND and the K6 Krukov. With their high rate of fire and long-range accuracy, assault rifles are by far the best type of gun in "Saints Row 2". The accuracy does start to degrade after the first few bullets hit, so there is more to combat than simply holding down the fire button. If enemies get too close, you may be better served by an gun that you can fire while on the move, like a submachine gun. However, for most of the game if you have rifle ammo available, you'll be using the rifle.
Other Guns
There are a few weapons that don't fit into normal categories. The McManus 2010 is a sniper rifle, used for one-shot kills at long range. The minigun fires dozens of bullets every second. There are also two rocket-propelled grenade weapons.