If your 27 is like my 32, the bolts screw into threaded inserts which are themselves threaded/stuck into the cabin top. Nothing goes through.
I took 'em off, filled the holes, and plan to replace them (and countermount handrails in the cabin while I'm at it) but to tell the truth I haven't really missed them.
The wood of my handrails was a lot weaker than I thought. The inserts were a lot looser and more corroded than I thought. Even at full strength the inserts are not an inherently very strong design. This knowledge made me look at handrails in a very different light: as originally installed, they might help with balance but they are not really a safety item.