What Rx said... and stay away from Tipton dummy rounds, I've found them to be junk in other guns, I use A-Zoom Snap-Caps and never had a problem with them in any caliber.
a wooden dowel down the barrel and trying to force it out would be my first idea. I am guessing the dummy rounds are out of spec or something got deformed on the dummy round
I would be lubing it a lot, down the barrel, before trying to force anything out.
Another idea, try to get the extractor to release. Again, add lube.