I also didn't crimp my RIFLE loads until I started loading for an AR10 in 308
I didn't do the lee factory crimp For safety issues since according to many comments on this type of RIFLE it wasn't necessary.
I'm a big fan of Berger bullets and I couldn't use them on this semiauto RIFLE and I started to do different things and I came up to find out that by doing the factory lee crimp now I didn't have to worry about jumping or not jumping the bullets.
I did found out that some bullets don't like this crimp and some do .
This is one example
Sorry but I didn't edited the pictures as to which is crimp and with is not, but my test result was that berger hornady A-MAX and NOSLER PARTITION do like the crimp WITH VIHT.N-140
BUT WITH IMR 4064 ONLY BERGER LIKES IT (IMR 4064 IS NOT IN THIS PICTURE
YOU CAN TELL THE DIFFERENT GROUPING THAT DOING THE LEE CRIMP WENT FROM 1.60 TO ALMOST .40 SUB MOA
CONSIDERING THAT THIS IS A SEMIAUTO RIFLE THIS .40 IS PRETTY GOOD.