I've never shot a Stock 2 prior to the match I shot it in. A friend contacted me and said she wanted to try my Shadow 2, so I said OK bring your Stock 2 and we'll swap. We swapped at the match and I took 2nd production after a GM, and second out of all the iron sighted handgun divisions.
In order to meet that 50, I'll likely swap on the spot with someone else down the line.