I did already pump with caliper off and the piston did not really budge. I'm wondering if they should have. I'm trying to isolate the problem and determine if it is in fact caliper sticking or possibly the brake line insides acting like a check valve. Thanks

 

Pistons in calipers should have extended when pumping the brakes. Don't understand how you could have pushed the pistons in enough to get the new pads on if the calipers are stuck so bad they won't move under hydraulic pressure. That doesn't make sense.

 

With BIG C clamp lol

 

I pumped my RR w caliper off. Could not get piston back in. So got a rebuilt caliper, gravity bled it. Brake not sticking any more.

 

I replaced both rear calipers and had neighbor come over to help bleed them. No dragging or sticking at all now. Brakes working fine. Thanks everybody!

 

Glad you got it fixed and thanks for letting us know what did the trick. Your thread may help someone in the future.