hey dude, whenever i surf the net and i always bookmark intersting things, my airgun bookmark folder has about 30 sites, anyway one of which is:
im sure you can find your sparrow target in there among MANY others. i would shoot plain round targets the same size as sparrow's kill zone, then switch over. 2 reasons, 1st you'll see and can better adjust your shots with grid lines. second, you wont waste paper and ink.
Also, try these pellets: RWS superdome, JSB exact light, etc Beeman kodiak.
If you have a gamo, pellets with grain values around 8 +/-.3 are excellent.
Both my gamo S1K and CFX perform superbly with these. I dont like the CP light that much, too dirty, a bit big in the bore, and just not perfect (molding leftovers running on the sides and head). This may affect accuracy that i experienced.