They exist, are in .50 and .54 . Very nice guns. Workmanship is vg, wood pretty, trigger amazing (single set trigger, ####, push trigger forward to set). If you can find one, buy it. I've heard they're $600 and up, but haven't seen any for sale less than $750, and they went fast.
Edit - thinking back $700 approx for a used one. I was fortunate with mine, but if you were buying normally, they're a nice gun.