Rick,
I have been loading plated bullets for years in many calibers, but have not tried them in 9mm, because I have a "ton" of 9mm FMJ bullets. The plated bullets start with very soft lead and then apply a very thin layer of copper to them. Xtreme bullets use a thicker coating of copper than others, and Berry's Mfg. bullets offer a double plated bullet. These two brands are my "go to" brands. I don't think that they are a accurate as FMJ bullets, but I don't shoot much beyond 50 Ft. at the range that I shoot at(senior eyes cause that).
In my experience/loading, I do not champher any of the case mouths, nor do I utilize a case gauge. I check the finished cartridges in the chamber(with the barrel removed) for the "plunk test". If my rounds pass the plunk test, then they are good to go. For my revolvers, I test them in the cylinders. Once I am satisfied with the finished product, I do no further testing/checking of my reloaded rounds unless I experience a problem.
Loading plated bullets are much more akin to loading lead, than loading FMJ bullets. I apply a good bell to the cartridge mouth so that the bullet will sit on the case mouth without assistance from my fingers. Not enough belling will result in "pushing" the plating up when trying to seat the bullet, and may well tear the plating. I do use a case lube to resize my brass(easier on my shoulder), but have not used any other lubes with my Dillon 650.
You want to apply just enough crimp to remove the belling. If you over-crimp, you stand a good chance of cutting through the plating. Load a couple of dummy rounds completely, and then with a kinetic puller, pull the bullet. You should find no more than a very FAINT line on/in the bullet from the case mouth. Any more than that, and you are over crimping.
These are the procedures that have worked for me with these bullets. I started loading only lead bullets back in 1972, and loaded them for years. As of a few years ago, I only load lead for 38-40 and some 7.65Para brass.......the other calibers(8-9) are loaded with plated or FMJ. On the Black Friday sale at Xtreme Bullets, I purchased 8K rounds of their bullets, so I guess one could say that I am satisfied with loading plated bullets for semi-auto and revolvers.
Hope some/any of this info will be of help to you.
