brake question

I have been searching this forum in hopes of clearing up a brake problem I have been having. I think I know what the problem but was hoping for a little insight from you all. I have been having a beast of a time with my brakes.

In order to get the brakes to work I have to pump them several times then they will lock up. I have spent countless hours bleeding them and sure I have the air out of the system. The car did sit for many many years without being driven and I read in a post that the master cylinder can be damaged if the brake pedal is depressed to far.

Does this problem sound like it could be the master cylinder? I was planning on removing it tonight and examining it but would rather not if I may be able to resolve the problem some other way.

Oh and yes when I pump the brakes the pedal resistance increases.

I realize this question could have many possible answers, I was just hoping that some of you who have had similar problems may be able to shed some light on my current dilema.

Thank you