Validating GURPS's ranged model : a GM on the range.

I often wondered what is my skill level in archery. I've been shooting for two years and have seen striking improvements between what the club beginners can do and how I shoot today. Let's crunch the numbers and figure out what is my skill level, and whether this is consistent with GURPS mechanics. I want to specify that I didn't try to make it fit as well as it did: I just threw in values that seemed reasonable from a GM's perspective. This post was inspired by a recent post by +Douglas Cole that can be found here. i once tried the same exercise with AD&D, and it didn't made a lot of sense.