Hyperco composite leaf spring question?

[Brads70]

Hello all!
I've installed Hyperco composite leaf springs 175# rate in my 1970 Challenger. They are too soft, car bottoms out on the pinion snubber to easy and if I put passengers in the rear it sits on the pinion snubber. So I ordered 225# rate and just got them yesterday. Using a vernier I measured them and found they measure exactly the same as the 175# ones! I figured someone at Hyperco screwed up and put the wrong decal on them. So I phone Hyperco and explain the situation to them. They quickly replied that yes they all measure the same but it's the material in the composite that gives the different rates? He also told me they ID the spring rates by a colored square molded into the spring. Sure enough it is there , the 175# had a green square, the 225# has a blue one.
Anyone use Hyperco springs and try different rates? I'm no scientist but not quite sure I believe the "different composite" story. I'm planning on taking one of the 175# off the car, flipping in over arc side up, standing on it and measuring the drop between the 2 rates? Sound like a plausible plan?
Anyone have experience with this?
Thanks Brad