Commercial Luger ?

I'm somewhat of a newbie on lugers,and need some help zero-ing in on a luger my uncle owns. It belonged to a relative of ours who was a lawman back in the early to mid thirties.It was purchased on the comercial market around the same time.It's a DWM,no chamber date,30cal,DWM proof marks and a 3inch barrel.Could this be a 1920's commercial. The 3inch barrel is throwing me off.Also it looks like at sometime the serial numbers on the frame under the barrel has been removed.The side plate is blank but the inside is marked with the last two number of the SN.All #'s match and the magazine bottom is wood and marked Germany.Any ideas on what he has?

Thanks

Mike_C