It is definitely Belgian; it is 12 gauge, but for 2 1/2" shells, not the common American 2 3/4" shells. The PV indicates proof with semi-smokeless powder, but the gun appears not to have been proved with smokeless powder, so caution should be used in firing it. Based on the general design, it probably dates to around 1900, but that is not certain.
It appears to be blued, not plated, but my eyes may be deceiving me. It also looks to be well made. I see nothing to indicate a maker, but such guns were often the product of a consortium of makers (one company made stocks, one barrels, etc.) so no maker's name was put on. If there is a marking on the rib, a picture of it might help in gaining further information.
Jim