Yep it's the Mk3 with black piston.

Here's a question for y'all - what oil do you use to inject into the piston. The bottle which came with the gun was almost empty so I'll need to replace it soon. I've already bought some 1mil syringes to inject the oil but I need to know what to use. I've got Ballistol for my rifle but don't know if I can use that on the webley.

Dean