This crimp tool is indespensible to create a dome after the star crimp has been established and the pre-dome has been set, but prior to the final star-crimping process. The is the vital  of the crimping process, which produces a compacted dome, prior to the final crimp. This step produces a necessary phase of compaction and tightening in the fold crimp, essential for a finish to your cartridge.

This is a great solution to get rid of case crumpling near the metal base. With this fixture you can use you can use sleeve with different thickness of plastic. The new sleeve will close much better. On older MEC 600s, you need to unscrew the bolt that holds the shell holder and you can easily install this device.