I have often reformed cases and find it a fun thing. Anyone can do it the 'factory way' but that's really not what being a handloader is all about, is it?! There are two common things that cause stiff chambering of reformed ammo.
First, you may not be setting the new shoulders back quite far enough. Try chambering a formed but empty and see if it chambers readily. If not, turn your sizer down another 1/16th turn (about 4.5 thou), see if that doesn't fix it.
Or, your necks could be dangerously thick because your new necks include part of the original body and shoulder. If you have a case fired in your chamber, carefully mike it and compare the diameter to the neck of a reloaded cartridge - you would do well to have at least 3 thou difference or you may have bullets pinched too tighly for safe firing! If you don't have a fired empty you may "paint" a difficult cartridge neck with a dark color felt tip marker, chamber it and see if the dye has been rubbed off the neck. If the necks are too thick all you can do is thin them by reaming or turning. Turning is better because it actually improves necks and that improves accuracy.
It would be very good if you (properly) anneal your finished reformed necks, otherwise they will split after a very few firings; Google "annealing" and/or Youtube for help. I'll just say NOT to heat the necks to a visible red glow, that will make them dead soft and have no real bullet grip.