A few people are a bit puzzled by the name or term Action Front. It actually comes directly from the U.S. War Department's drill manual, Instruction For Field Artillery, originally published in 1861. On page 313 there is a section for "Formations in Battery". Number 530 is written when pieces are in line, to form in battery to the front by throwing the caissons to the rear. Basically what that means is your battery is already halted and you want to unlimber and get ready for action to the front. It's business time!
I had read many years ago that the 9th Massachusetts battery (led by Captain Bigelow) at Gettysburg was facing the Wheatfield Road (just east of the Peach Orchard) waiting at the halt for further orders. The command was shouted and the battery sprang into action. Limbers would have been moved forward and turned around to unlimber the guns. Artillerymen spring to their assigned posts ready for action. Section commanders order the targets to the Gunners and the Gunners in turn choose the appropriate rounds to be loaded.
The NPS had a sign posted along the road with a drawing of the action above with the 9th Massachusetts. Of course the battery would cover themselves with glory fighting later that day at the Trostle farm. I tried finding it this trip and it's gone. It could have been removed a few years ago, I don't know for sure. Anyway, the words "Action Front!" written on the plaque has stuck with me all these years.
There it is... the title.