Hey Bret,
The latter 100s had the full engraving. If it has a full beaver tail then it's a 150. It should also have a pin where the older ones had a screw on the sides of the frame. Is it a 3" chamber? The early ones were only 2 3/4" except the 20s, latter guns were usually 3" in both gauges.
This is a 150 to my understanding but you can see the pin up by the hinge.
http://www.gunbroker.com/Auction/ViewItem.asp?Item=90578510This is an older gun
http://www.gunbroker.com/Auction/ViewItem.asp?Item=90578510The less engraving the older.
No 17s at the show eh?
Tim