The short answer is yes you should be able to chamber an empty sized case, assuming it has been trimmed correctly and the shoulder is not out of tolerance. It can be worth your while to invest in some tools like the RCBS precision mic for your caliber and also the RCBS case master.
I have not taken any surveys lately, but I know most shooters that hunt around here and reload DO crimp their rounds, bolt, lever, single shot or auto. However, they mostly crimp as a separate process from seating. When properly used, collet crimpers such as the Lee Factory Crimp die can be of benefit to all shooters. Please note the foregoing caveat.
Crimping serves two purposes. For ammo that may be subjected to shocks, either from firing or dropping the rifle or some other whack, crimping keeps the bullet in place. A good many hunting bullets are cannelured for just this purpose and have been for years, the world over. Crimps also help to uniform start pressures in rounds that have not been loaded with super close tolerance (expensive) dies. However, in order to do that the pressure used to apply the crimp must be closely regulated and over-crimping avoided.
Many older shooters still think that a cannelure is needed to crimp a round, and when they do not see one, the assume that the ammunition is not crimped. This is not true, and is the basis for the invention and marketing of the Lee Factory Crimper.
Unless you are shooting a very tightly spec'ed custom rifle, like a benchrest or long range match rifle, and loading very tightly spec'ed ammo, a good crimp can help a bit.
