I was recently loading some Speer 180grs when I ran into a similar problem. Took a sharpie and painted the bullet and front end of the shell. When I attempted to chamber the shell and ejected i there were faint rifling marks on the bullet. Next batch I seated the bullets as deep as the cannelour would allow and still crimp. Previously I was crimping middle of the cannelour, probably gained a few thousands, allowed the shell to chamber easily.
