These dies will allow untrimmed brass of varying length to produce uniform velocities, and also allow crimping where there is no crimp groove, with jacketed or cast. Whether they provide as much bullet pull as normal crimps, I don't know, but I presume it will and for sure it will be close, with NO ROOM FOR ERROR! By that I mean. If one is loading brass of varying length in standard loading dies, a long case will buckle/swell slightly when the crimp hits the bottom of the groove. If a case swells at all it will lose most of it's bullet grip. If one tries to get all the crimp grip possible by bumping the crimp too hard, the same problem arrises on every round. The lee factory crimp of this design will solve all that.
By contrast the Lee Factory crimp pistol dies have a sizer ring which, if it sizes the cases, which it is designed to do, over a cast bullet which is intentionally oversize, you'll be able to spin the bullet in the case with your fingers. Also, the crimp station in these dies is the same as all standard dies. Lee pistol factory crimp dies are trouble waiting to happen. Don't use them.
But these new dies would be an excellent die to have on anyones bench, one for each caliber. An inexpensive investment which can solve loading problems that can't be solved any other way.
