I am relatively new to reloading. Reading the instructions with RCBS dies indicates that crimping can be done with the seating die.
1)Is this what would be called a taper crimp?
2)It seems that turning the die down to initiate the crimp also seems to alter the dimensions of the case shoulder making the finished cartridge more difficult to chamber.
What am I doing wrong? I am assuming that this should not be occuring. Note, I am adjusting the die down only 1/16 of a turn.
Thanks.

What cartridge? Various cartridges take different crimp types, tapered or rolled.

If you are loading a bottleneck cartridge such as the 223, `06 etc, not crimp normally needed. If the bullet doesn`t move under hand pressure or recoil I would not crimp. JMHO>

RCBS rifle dies are usually roll crimp! I load everything up to 338 win mag with out crimp and taper crimp with seperate die for straight wall pistol case's like 45acp and 9mm. If you roll crimp too much you will fold the sholder back causing chambering problems on bottleneck cartridges! and if you taper crimp too much on pistol cases it changes the shape of the bullet and will look good but may not chamber either! Hope that helps! Curly

I am in the "I don't crimp" camp and I've loaded some pretty potent cartridges. But that doesn't answer your question too well.
Of the cartridges I have loaded that did need a crimp: 30-30's with tubular magazines, I was never able to set up the die to seat a bullet and crimp at the same time. I always collapsed the shoulders enough that they wouldn't chamber. So I always had to seat the bullet and then crimp the cartridge in different steps.
Make sure your seat die is set up right. Screw the die down until the die is touching the mouth of the case and then back off a couple of turns and lock it down. Then adjust your bullet seater. Each of your cases need to be trimmed to the same length. Then seat your bullets to where the mouth of the case is about 3/4 of the way to the top of the channalure. Now for the crimping step, back the bullet seater out several turns and then turn your seater die down until it touches the mouth of the case. Back the case out and turn you die down 1/4 turn and lock it. Cycle the cartridge thru and see how your crimp looks. If you need a bit more, then loosen the lock ring and turn it down another 1/4 and so forth. I found when I trimmed the cases to length and chamfered the mouth of the case and deburred the outside, I would do a rather vigorous job of deburring so the outside of the case mouth was kinda tapered. Then it seemed to fold into the channelure easier.

Hold the cartridge in your hand a see if you can push the bullet back with your thumb.If so you need crimp.With a revolver or magazine fed gun check if firing sets back bullets in the magazine .Powerful revolvers are more likely to do this.
Cartidges that headspace on the mouth [45acp, 40S&W, etc ]need a taper crimp.Others use a roll crimp. Don't crimp more than necessary.