i have tried many ways to straighten armor plate, ball peen hammer on the soft side, air chisel with a blunt tip on the soft side, heat.
none of these have worked.
i have had great luck using a press brake. i straightened the rear armor of my m16 halftrack this way and it came out perfectly.
first draw lines every 2" 90 degrees to each other, hard side will be up. set up a press brake with a lower die of 2". this press break im using is a 290 ton but you don't need one that big. bring the top die down on each line with a slight deflection of the plate and see how it looks. i ran each plate through 3 times lowering the top die each time until it was good.
repair any cracks in your armor before doing this.
the lower pic of the door is how the military did it. im not sure what they used to do it but there is very small cracks at each dent on the hard side.
