Unlike many others on this forum I have actually tested the Lee Factory Crimp die in several rifles, mostly semi-autos. I have tested it from light to heavy and with dozens of different bullets both with and without cannelure.
Here is just one of hundreds of test targets testing the LFCD. Same load except for the crimp. Target on the left no crimp target on the right LFC.
I'm not sure as I do not have my notes in front of me, but I think this target was with 53gr Sierra Matchking.
I know, I know, not a large enough sample, only one target, means little or nothing etc. etc. Like I said this is just one of hundreds with similar results. Can't post em all now can I.
For those of you that have nothing good to say about the LFCD how about posting some of your targets where the use of the die degraded the hell out of accuracy?