shotshell reloading problem

[Classicvette63]

So I'm reloading shotshells the other night on my mec single stage press. I'm loading AA hulls until I run out. Everything is fine. I switch to Federal hulls and there is a problem. When I do the final crimp, it sinks down too far to the point where I can dump the shot back out of the hull. Obviously the Fed hulls are slightly longer than the AA hulls. Any thoughts on how to fix that? I really don't want to have to knock 250 good primers back out. Thanks