Here's an orange tip I made for the DeSteiner Revolver II (https://makerworld.com/en/models/162780?from=search#profileId-215962). There are two tips here, one for the shorter 72mm length barrel and one for the longer 154mm barrel.

These slide right in and snap at the back of the barrel. It will stay in place, but you can still pull it out pretty easily.

I made this because I want to use the gun as a prop in short films, but I don't want to get shot or fined on my way to and from the set.