Unlimited is the opposite. Guns in this class have at least a dot sight, and they are almost always tricked out as well with slicked up triggers, comps, and more internal gunsmithing. Some clubs will limit automatics' ammo capacity to eight rounds, sometimes even to six to allow a fair chance to revolver shooters. Granted, you should only need five, because if you have to reload, you've probably already lost. Don't snicker at the wheelgun slingers.
Revolvers are still a very formidiable gun in the arena of the pin-blasting world.
I recommend starting out in .22 limited class. Using a .22 allows you to concentrate on all the basic requirements of the sport, without having to deal with controlling a big handful of recoil and noise. Bowling pins might not look very tough when you throw a 16 lb. I know it's hard to force yourself to go slow at first, to aim carefully at each pin. When the guy before you knocks those pins down in 3.07 seconds with 5 shots, and you take 18.94 with 8, it's especially hard to concentrate on aiming.