The design of the Garand is not conducive to being highly accurate. They can be accurized, but are not the equivalent of high quality bolt rifle. Have you ever accurized a garand.Old as I'm getting, that M1 Garand may hold a better grouping offhand at 200 yards than most precision/or less precision Bolt Actions. YMMV.
For off hand shooting the trigger is very important. The bolt gun with a custom after market trigger will beat what ever you can do to a garand relative to the quality of the trigger.