Roger,

It would appear that your Riot Gun was one of the Texas (Galveston) guns. 

With the PR date and Received in warehouse date being just 1-day apart, it appears that instead of pulling an already assembled gun out of the warehouse and converting it from a Standard (Field) gun to a Riot Gun, Winchester simply used an existing Standard barrel and cut it down before assembling the gun. 

Please send pictures of the gun to me when you get a chance to do so.

Thanks,

Bert