Ok, that's odd, but in a good way I guess. NEF doesn't list a sportster SS1 (single shot) or sportster SL1 (semi auto-loader) in 17hm2, and I can't find it in a big distributors list either.
So you're going to have to give us the specks. Is this a single shot or semi auto, what stocks, barrel contour, etc?
And I don't want to insult, so don't take this question that way, I don't know you or anything about you or your knowledge of firearms. That said, is it a single shot bull barrel with 17HMR written on the side of the barrel right above the breech?
later,
scruffy