As does a sizing die.Properly set up, it forms to the proper dimensions.
You're putting a .452 bullet in a case and cartridge designed for a .451 bullet. That will bulge brass. Run then in the FCD and it will swage the bullet (thus removing the bulge). That's fixing one problem and creating another problem.So how is it one out of every five or six .45acp rounds I produced without using the FCD, would not chamber because the projectile "bulged" the case. Mind you I went thru all kinds of troubleshooting with other reloaders to try and fix this problem when I was using the 3 die set up and the only solution that remedied it was the FCD.
If post sizing loaded cartridges is so awesome and necessary, how is it that only one profit driven company in this industry offers such a die? It isn't patented. None of my ammunition loaded with Redding dies ever has an issue with making proper dimension ammunition. Lead, plated, jacketed.