Thats a Great idea. With all the Coyotes and woodchucks and field mice yo need something short & handy that will pack a varity of loads. A revolver does that. Load a chanber with birdshot and the next with some paper patched wadcutters at reduced power, then go for hollowpoints in a couple of chambers.
Just know & shoot your rotation so that you never miss.
Is a sholder holdster better or do you make a rak on the mower next to the beer holder?
Maybe a little six pack cooler with a holdster screwed or velcrowed on to it whole rig bungcorderd down on the front of the mower.
lets see your Easy Mower Rifle Racks designs.
"Maine Sure its Cold, But its a Damp Cold"
Capt Walt