What kind of ammo? FMJ, HP, conical nose HP? 115gr.,124gr.,147gr.?
Plunk test--(hope I'm explaining right)--
Take your "Clean" barrel out of pistol, and hold with chamber pointed up. (Tip of barrel down)
Slide round in with out pushing hard.
You should be able to spin round easily without problems.
Rotate barrel up and the round should drop right out into your hand.
If it sticks in the barrel, and can't spin around, and you have pull the round out, it's too long for your chamber.
Edit to add
FWIW, if the ammo survives the plunk test, I would try a little more lube on the slide and see how that works. Here's a great polishing thread.
http://www.czfirearms.us/index.php?topic=42537Czech out the gunsmithing section, there's lots of threads on polishing.