It’s not that the U.S. army has refused an Automatic loader system. It’s that they just haven’t been in a position to do the major overhaul of the Abrams that would justify it.
The Thumper and CABBT (American Armata) both demonstrated automatic loaders. The XM1202 Mounted Combat system also was intended for one.
So what?
So Thumper and CABBT were very end of the Cold War. Right as BRAC was kicking off. After the 91 Gulf war it looked like the last of the armor on armor wars. With the Western Armor and Air power so dominating it looked one sided. The Question for the Army was What’s next? You have a mindset that the Army’s foreseeable future was peacekeeper.
So the Army tried to justify itself in a model based on the Yugoslav war. Thing is if all you see is old Soviet surplus armor at best more likely just a Hilux with some steel bolted on M1A2 is more than enough.
If anything the push was to try and field light armor. The Stryker and FCS programs.
Though FCS was supposed to feed into a major overhaul of the Abrams. Post 9/11 the Army is getting into operations in Iraq and Afghanistan COIN becomes order of the day.
So the opportunity isn’t there.
They are doing modernizing of the M1A2 with the Sep V program and in theory they could have added an Automatic loader with that but, the weight of the Abrams is climbing. Adding the loader to the A2 Turret isn’t going to offer a huge benefit. Tanks like K2 and LeClerc get a weight savings by reducing the size of the fighting compartment for 2 people as opposed to the 3 in Leopard 2, Abrams and Challenger.
So to justify the loader you need to replace the turret at which point you are basically shopping a new tank. Which is what M1E3 is really going to be.