Since military sniper rifles are now being made of composite plastic, instead of old fashioned wood, it can be assumed that plastic, at least theoretically, is more accurate than wood.
I think the bigger question is are there any plastic stocked M/L rifles being made now that are more accurate, or as accurate, as some of the wooden stocked one? If you consider some of the custom rifles built by the best gunbuilders around, some of them here on this forum, well, it's not even close. I really don't think those CVA bobcat and plastic stocked T/C designers put alot of emphasis on built in accuracy. Plus, I doubt if they would know where to start. :rotf: They build guns they think will sell, bottom line.
Also, like Zonie alluded to, the guys who buy those kinds of guns tend to be the more sloppy shooters, as compared to a guy who will fork out big bucks for a custom wooden rifle.
If you ever get a chance to read up on some the gunmakers and target shooters of the late 19th century, You'll be amazed at the knowledge and skill these guys posessed. Incredibly small groups at 1000 yards! Hard to believe those were done with handmade muzzleloaders, but these guys really knew what they were doing.
So my answer to your question is, you need to consider the whole package to decide wheather plastic is more accurate than wood, and that includes the shooter. Bill