The biggest problem is if you are using old, hard brass that actually "springs back", after going through a FCD, while the bullet was made smaller. Perfect formula for setback, and blowing up a gun.:yikes:
I started using the FCD after bulging a number of 223 cases with a RCBS combo die. Ultimately, the RCBS dies had some galling in them. I have since switched to Hornady dies.
The easy setup and performance of the FCDs, convinced me to get them for all six calibers (rifle /pistol) that I currently load. I don't load in high volume and the consistency of the finished product ( for me ) is worth the extra step in the process.
If your brass was not oversize after seating the bullet (for whatever reason) before entering the FCD, it (the FCD) would have no effect other than the finely adjustable taper crimp that would be applied. The die only "sizes" down to factory SAAMI spec on the outside, squeezing the odd round that due to tolerance stacking will occur when loading mixed brass, and usually lead bullets. I don't agree with your argument, at least not as a general statement, that may erroneously lead others to a false conclusion.
Love it or hate it, but let's leave the arguments realistic, please.
You didn't read my reply. The only springback that should happen if you "carefully choose the proper components" would happen during the resizing operation (first stage of reloading) as the "proper components" assmbled "correctly" would slide through the FCD without incident, other than the taper crimp it would apply. This happens with most all assembled loads. Most of the "bulging" of the case after bullet seating comes from lead bullets, thick wall cases (having been properly OD sized by the sizer die), and possibly oversized bullets, or some combination thereof.
The argument that the FCD sizes below SAAMI dimensions is false. Unless the case is bulged larger than that (due to improper sizing?!?!?! - according to some), the FCD sizing ring does not touch the brass, so no squeezing to a smaller size, springback, etc. or otherwise would happen.
Have the naysayers ever tried the die? I don't think so. My opinion is that some guessing is feeding most of the arguments.
Ding-ding! To your corners, boys.
I use the Lee factory crimp dies on all my 9mm,.40 S&W,45ACP,and 10mm Auto bullets.
I love the product-and the reliable bullets it produces.
Each to their own fate.....
No problem with my 270FTWin, 9 and 10 million metre, Tree Eighty, or TooToo Tree versions.
And I crimp very heavy.
Lee products are vastly underrated.
The Lee FCD was meant to be used with FMJ bullets. Many mfrs. of plated and coated bullets such as Precision Bullets specifically recommend that you not use the FCD.