Speer’s tests, and those by another bullet maker and an independent gun writer, show that crimping a bullet that doesn’t have a crimp groove degrades group size by an average of 40 percent. Other than the crimp die, we have no problem with our bullets in that firm’s dies, although our preference is for RCBS® products.
We express ours thanks to the die maker for allowing us to make contact with so many new SPEER customers.
Kind of a he-said she-said. Lee makes pretty tall claims about its dies and especially the factory crimp die yet I don't know of too many serious reloader who would crimp a rifle bullet for better accuracy, on the other hand Speer has a lot of interest with RCBS- their reloading manual is included in RCBS reloading kits. If it weren't for Lee, RCBS would probably be able to sell their dies for twice the price.