What you have is a stainless Super Single Six. The "Single Six" has a windage-only drift-adjustable dovetailed rear sight and a "half moon" front sight (like the old Colt SAA). The "Super Single Six" has a screwdriver click adjustable rear sight, adjustable for both windage and elevation. As you have already found out, it was originally a convertible, and should have had both the .22 LR and .22 WRM cylinders.