Without any rounds in the chamber and with no mag installed, it should rack smoothly by hand. If not, then the slide is grinding against something that it shouldn't be. Perhaps the frame is bowed, perhaps there is a bur, perhaps something didn't go back together quite right. If it isn't racking smoothly by hand now, did you try racking by hand without ammo before you took it apart? If it was smooth before, then strip her down again and reassemble. If it is together correctly, then strip her down again anyway and look for burs or wear points between the slide and internals.
Yes, the spring is strong, but it definitely shouldn't be "binding" against anything inside - even when brand new. One way to test this is to remove the 2 long springs and reassemble without them. Then you can feel if it is hung up on something inside.
I would be hesitant to shoot it if it is binding up when you hand rack it. Not meaning to worry you, but I recall a few others on this forum who reported stiff racking when new and ended up having no end to problems trying to get it right. If it is together correctly, you can't find anything wrong inside, and it is stiff when you rack, then I would recommend returning it for another one. Preferably chrome, as they seem to have fewer problems.
Hope this helps, let us know how it turns out
