I am not an expert, though I have been corrected by plenty over the years.

It is flat under the forearm like a Winchester, the M2 cut is not factory, the wear & dings looks honest, the #8612 stamped inside reeks of a Bavarian past and while the cartouche is nice, its not too nice. I'm not familiar with the seller, but it looks like he specializes in real USGI gear.

My uninformed opinion is that it is a real Winchester stock. That and a buck will get you a cup of coffee some places.

Why do you think its not?