There were a couple of minor differences...the original No. 1 had a trigger that was adjustable, while the No. 3 did not.The #3 needed bases to mound a scope, where the #1 has the Ruger integral mounting system. Barrels, sights and stocks were different, though buttstocks were interchangeable and the forend attachment was identical. The major visible difference was the No. 3 uses an "S" curve lever with a detent to hold it closed while the No. 1 has a triggerguard with a British type lever and latch.