Can I convert my standard 391 Urika to an Optima Bore?

convert to optima bore

Yes, standard bore and Optima bore barrels are interchangeable.  In addition to replacing the barrel a new fore-end will be required. The fore-end is needed due to the fact that the Optima Style barrels cannot use a non-Optima style fore-end due to the dimensional differences between the two-barrel types.