Go to this site and ask the same question. The best source for A-5 answers I have found on the net. If you own an A-5 you have to bookmark this site.

Shotgunworld

I'm not sure if they had a lightning. I think it's just called a "light" They originally had three models I think. The standard model, the light model and the magnum model. The magnum would chamber 3 inch shells and the standard and light will chamber 2 3/4 shells only. I'm not 100 percent sure on that though. Considering they have been making for close to 100 years.

I have a stalker and it says Auto 5 light on the reciever.

Also the browning site does a poor job of dating these guns from what I understand. Some of these guys can do a better job if you want.

Paul