I was a Browning dealer from the 1973 to the mid '80's. The early BSS models had pistol grips, NSST and silver colored triggers. Gold colored triggers followed and represented SST. I have never seen a factory Sporter with a silver colored trigger.

I currently own three BSS all with SST and gold triggers - two Sporters, one Japanese and the other assembled in Korea, and one pistol grip with 30" barrels.