Meaning what "concerted firepower" might have made for a difference IF Custer's portion of the 7th could have made a coordinated and unified advance down Custer Hill towards the upper ford. And not advanced almost a company level to the south and mostly west down the hill.
On the other hand, being ground up pretty much piecemeal, they did not get to use the "firepower" their Colts could have provided at close range.
But then again, Custer hoped to force the upper ford (incorrectly) thinking that Reno's battalion was sweeping through the village could have met him.
Don't look it up...
Popular history has Custer first advancing down Medicine Tail Coulee to the ford and being met by warriors rushing to meet him so he retreated UP Custer Hill and was wiped out in retreat not in advance.
The National Park Service invited me to speak my heresies at the Little Big Horn for the 105th Anniversary.