The Mrs. has a very nice Browning Buck Mark Camper. I bought it second-hand, but it is immaculate. She has fired a thousand or so rounds through it with no problem except the occasional failure to fire (about 1%), which is normal for .22LR. We have been using Remington Golden Bullets, which seem to the the best currently available.
Today she was doing failure-to-fire drills, ejecting rounds that had actually not been fired; and the slide locked up in the closed position. All my strength (which is not impressive) could retract the slide only about 1 millimeter.
Before this occurrence, she had probably fired 200 rounds in about 20 minutes (steel plates quake in fear at her name

So we went home. I researched the issue on the internets and could find no similar account.
Then I retracted the slide in the usual way, and it operated normally. The chamber was empty.
I cycled a number of rounds through the pistol. Being at home in town, I could not fire them.
Any ideas?

- Jim