RE: Lyman Pin Wedge
If the gun has 2 pins I can see how one could come loose, especially if one were more bent or curved than the other. Once he has the new one, and if the gun has 2 pins, try to get them so they are both under the same tension when in place.
A zip tie may help keep the barrel from falling out of the stock, but shooting like that is not a great idea, even with ramrod in place. Bailing wire on the other hand, would work just fine.......jk.