Yes, there can be substantial difference between chambers, particularily from one mftr to another.
FL sizing to match your chamber is the key. Overworking the brass is not what you want before you start resizing.
Best place to start is do a lot of reading. Get a sinclair catalog www.sinclairintl.com
and RW Hart www.rwhart.com
. They have all the tools you will need to work with.
A pretty good book to answer 95% of your questions is "Handloading for Competition" by Glenn Zediker. gives very good explanations of things and how to dos. Sinclair normally has it or look at Amazon.com. Right now it is about the best out there.