Smith serial numbers can indeed be confusing; but your gun actually shipped in 1928, the key here is the serial number prefix "RE" denoting the gun was made on a "regular" size (or "R") frame and has factory installed selective automatic ejectors ("E"). The Crown grade is a beautiful example of one of Hunter's high grade Smith guns and was produced from 1913-1950. They were very popular and Hunter sold about 900 Crowns; so they are only rare in smaller bore sizes (especially in .410). As to a value range, Crown grade 12-bores with problems are ocassionally seen in the $2500 range, while an example in mint new conditon with options may bring $15K. With a 12-bore example having cracked wood behind the lockplates, thin blue, non-factory checkering, (probably other probems as your description indicates a gun that was used), this gun wouldn't be highly desireable to a fastidious collector; therefore its value will not be on the high end of the value spectrum. These guns in the condition described are collected by shooters however; but they will consider the cost of needed repairs in making any offer. Finally, your grandfather left you a great gun that you should hang onto and someday have professionally restored. If you decide to restore the gun, we can give you the direction you will need to accomplish that goal; in the interim, post a few pix and let us see the gun first hand.