Gougler keyless padlock combination?

[wylk]

It is fairly unusual for a product to exactly match its patent. In this case the patent itself is more for the locking mechanism and general layout, and the two screws you mention were probably wisely replaced with pins. Otherwise the screws could pose a significant security risk.

I would say yours is not a prototype but I feel it's an earlier model. I'll attach images of a similar lock that looks much more crudely cast, possibly not even brass. I don't own this one, I just ran across the images from a 2008 eBay auction.