A heavy L frame with a short barrel in a clip on holster is gonna flop around a bit. If you need an easy off/on holster, have you thought about a paddle holster? Wright Leather Works makes great stuff:
You need a paddle holster: Kramer MSP paddle rig, or if you're looking for a easy on/off rig I use an IWB holster. Two snaps undone and it is off. Goes on the same way and two snaps to secure it.