Like guncrank1 mentioned waaay upthread, this is a subject that was discussed in an old thread. I'd like to pass on some info that I passed on in the original thread about the Colibri in my Sportster.
It was actually my son (10 at the time) who was shooting cans at about 20-25 yds. The rounds were so quiet that we could only hear the hammer coming down, and the 'tink' as the bullet hit the can. After shooting for awhile, and hitting every can, he fired another shot and we heard the hammer hit, but not hear the 'tink' nor see the dust behind the can. He ejected the empty case, and put in another to shoot again. I stopped him and checked the barrel. Sure enough one of those teeny bullets was about 2/3 of the way, stuck down barrel. Poked it out with a cleaning rod and ran some bore cleaner and a few patches through. Dirty, dirty, dirty... We kept shooting after that, but cleaned the bore after finishing of each box of fifty Colibris.
Something to keep in mind - we had no problem with stuck rounds with a Ruger Single Six or a youth Henry with 18" barrel, just the Sportster's 20 incher.
In any case the Sportster is a lot of fun whatever we shoot in it.