I have a Series 188 Ranch rifle with factory scope mounts. I purchased a Tasco 6x24 1/8 moa Dot Target Scope with a 55mm objective. The factory mounts from Ruger are just a little too low (1/16" +/-) to allow scope mounting without contacting the barrel, which is factory configuration. As close as I can tell, the distance from the bottom of the factory mount to the bottom of the inside scope ring is about .425 " on my factory mount. Can someone recommend what height (and brand) of mount I need to mount this scope?