Rear Break Help!! piston won't compress!

[350teddy]

Iv tried and tried compressing the caliper piston and it only has about 3/8 more to go. It should compress all the way down without messing with the piston screw right? Is there a trick or something I'm doing wrong?

 

[lbjamm]

You have either the bleeder open or the cap off the master cylinder?

 

[350teddy]

I do. Idk what else to try. Could it be damaged to where it won't compress any further?

 

[lbjamm]

You using a c clamp to compress it?