With a conventional bullet it is easy to crimp them in place with either a taper or roll crimp. However with a heel bullet since the bearing surface is the same diameter as the case mouth, they cannot be crimped in the usual way. We have crimp die (not a full die set) that is designed to crimp heel bullets. The case needs to be loaded and the bullet seated and this die will apply a firm crimp to the case mouth. As the cartridge is pushed up into the die it applies pressure to a collet that then compresses onto the case mouth, crimping the bullet into place.