Question about shotgun primer

[J.B. Books]

Originally Posted by Jim Partlow

Paul.... Where does a roll crimp fit into the
Pressure quotient? I have read somewhere
that roll crimps offer less resistance, thus less
Pressure. Would appreciate your input.
Thanks Jim P.

Roll crimps reduce pressure slightly but it is hard to know exactly how much in each case. Personnally I will estimate/guess 500 psi on average when using it over a fold crimp recipe. Here is article from Ballistic Products with a few side by side comparisons. As you can see it can reduce pressure by as much as 1500 psi or as little as 100 psi.

http://ballisticproducts.wordpress.c...-a-fold-crimp/