93: The "Tin Hat" is an old British Army target, used in competition for pistol & rifle shooting. Colors of the British Army target were black and sand/khaki, also IIRC. It is supposed to represent, roughly, a soon-to-be unfortunate fellow peeking over the top of a trench. Thus, you know after which Bruhaha the target became popular.

I have used it extensively with pistol, making up copies on typing paper using a copy machine. The flat surface of the bottom works pretty well when mated with the flat top of most modern pistol sights. The roundish top of the old semi-circular front sights on S&W service revolvers is a bit more challenging but the target is a good one none-the-less.

You question is an excellent one.

Regardless of what target you use to zero {I have several I can post pictures of if you like} check final zero from a field shooting position on a non-distinct, asymmetrical target. You may be surprised to find the zero you used on the bench on a round target shifts a bit on a target such as the Norwegian reinsdyrblinker, an excellent practice target and one used for the annual shooting test required to obtain a hunting license in Norway. Using the same concept I've designed several of my own, and they make for a much better practice target in my opinion than round "Bullseye" targets. I haven't seen many game animals sporting Bullseyes!

This is quite an interesting topic, and if you look at the test targets that accompany various rifles and of course those used in military production testing you'll find quite a variety.

Right now, I'm discussing with the Idaho Fish and Game Department the design and adoption by them for use in the Hunter Safety Program of a target incorporating the asymmetrical, non-distinct aiming properties of the Norwegian government hunting target. With nothing to draw the eye to a "center" it forces the placement of the sights as they must be placed in the field and as a result is an excellent teaching aid.