Jani:

During WWII when Remington took over production of the A-5 from Herstal, they made that change........and after WWII when Herstal produced them again that change was retained.......

http://en.wikipedia.org/wiki/Browning_Auto-5

Remington had been building guns with rear trigger block saftey's since the turn of the century, so it was a natural change for them.......

Best,


Doug