I have come by a White "White Lightning" muzzleloader, 50 cal which uses the small percussion cap. It looks good, is all stainless. Has anyone heard of this company or know where they are located. Also are these guns any good?

White is located in Utah. Doc White started to company and still does research and developement for them. White rifles are designed to shoot large lead conicals and they do a good job of it.
look here
http://www.whiterifles.com/
and here
http://www.whitemuzzleloading.com/

Walker has steered you in the right direction. I hunt with a White G series myself. Very good rifle. Easiest muzzel loader to reload ever made.........

I have two Whites: a 97 Ultra Mag laminate, and a Super 91 composite. Both of them will shoot less than 1-1/2" groups with 100 grain equivalent (70 grains weighed) of Triple Seven and the 250 Hornady SST/Mls. Matter of fact, the first three bullets out of the Super 91 after it came in went into 1-3/8".
And I love the way they come apart to clean. There is nothing like being able to completely go from filthy to beautiful in less than 10 minutes.
(And stay with the #11 percussion cap. That is what the rifle was designed to use.)