It is common to hear of the 33/40 called a "smallring". The weakness of such terms is that they are generic and are both right and wrong. It IS a smallring of sorts, but it isn't in the sense of the smoothsided Mauser 94, 95, 96 and transitional models.

OK, so it lacks the BUGN proof, but per Speed, has the Crown/N indicating nitro proof years 33-39, export model. StmG indicates a full metal jacket bullet type. As for the serial number, doesn't it fit in the range and placement of transitional models?

Speed says parts were known to lay around for years before being assembled.

So...?

Rick R, can we bother you to shoot a couple pics of the bolt, specifically the gas vent holes?