I was looking online for snap caps but can only find them in amazon and canadian tire and they all have bad reviews. I do like the washers in a spend shell suggestion
Take spent shotgun shells put wooden dowel that’s a right fit viola shotgun dummy shells
I would strongly suggest AGAINST the red snapcaps. I had a terrible time trying to cycle them through several (different aged) Wingmasters. Would not eject, would not load...
I ended up giving them away when I sold the shotguns.