Do you chamfer your springers' barrels?
I've been thinking about doing it for a while but leaped in after a 1,5" 3 shot 15m group tonight with my Hatsan Mod 33. It bothered me that this barrel had an almost tangible hanging edge around more than half the chamber, that looked like the blade of a hunting knife when you've just taken the medium stone out of your Lansky and are about to put the fine stone in.
I used a medium-sharp 6mm drill bit in a tap wrench and made two complete circuits with a bit of pressure with very little pressure on the third to clear out swarf.
These barrels are like butter.
Apologies for the poor quality pics at night with my Blackberry, but I think you can see before and after and the nice seal around the pellet now.