There are many more examples;
The Union Forces were offered Repeating Rifles with Cartridge Ammunition (Henry Rifles I think)
The Northern Quartermaster turned them down because he thought they'd fire too fast and waste ammo
One Northern unit managed to get equipped and take them into combat
The Southern General complained about "that @&%$! Yankee rifle you could load on Sunday and fire all week"
And more modern;
The F8 Crusader, a true fighter, was cancelled
And the F-111 Aardvark, a multi-role waste, ordered into production
And just recently, the F-22 Raptor, unmatched stealth fighter, was cancelled
Oh and about Custer, he declined to take his Gatling Guns cuz he thought they'd slow him down
What Civil War Battle was that with the Bird Shot in Smooth Bore Muskets?