I have used once fired 30-30 brass from Winchester, R-P, and Federal, all with good results. I use the same amount of Hornady one-shot that I would for standard full length resizing, and have never had any problems.
I start the forming process with my sizing die backed out to where it's barely forming the case. Insert the case in your barrel to check how far it protrudes from the chamber. Adjust the sizing die a little at a time until the casehead protrudes from the chamber around .002" or so. Then close the action to test the shoulder depth. It should close with just a little effort, you shouldn't have to slam it shut. Now the bulge you made in the neck of the case when resizing is tight against the shoulder of the chamber. Now you're ready to load some cases!! I use my standard powder charge to fireform, and have found the fireform loads to be as accurate as using pre-formed brass. Hope this helps!