I always thought the rear trigger had a harder weight of pull to help prevent recoil-induced discharge and that the front trigger first, was "the proper sequence". Elmer Keith recommended firing the rear one first as he said it made it easier to fire more quickly, as recoil moved your hand forward, to make it easier, faster to access the front trigger. Elmer had fairly small hands & this makes sense from that perspective.
-------------------- Daryl
"a gun without hammers is like a Spaniel without ears" King George V