I had the same problem when i got one of my handi's , a good chamber polishing will do wonders for it. The best way i have found to do this is with a spent round .
1 de-prime the case then screw in a small hex head sheet metal screv in the flast hole .
2 put a small amount of metal polish on the case .
3 use a batt. drill to turn the case slowly in the chamber , removing the case to wipe out the chamber and repeat as needed .
This should cure the sticking problem , also make sure the chamber is free of oil or other moisture when shooting .