07-07-2021, 03:42 PM
I resized some Lapua 6.5 Grendel brass to 6mm ARC as well. I had no problems seating Hornady 103gr ELD-X bullets but I used a Wilson inline, arbor press bullet seater die instead of the Hornady seater. I don't know what would have happened if I used the Hornady seater.
I did notice the Lapua brass was a little heavier/thicker than Hornady or Starline brass. Sizing it down is gonna make the case necks walls even thicker. What is the actual diameter of your 6mm mandrel? The diameter of the neck expander in my Hornady sizer die is .241". If it's larger than that, because of the thicker brass, it could cause a too tight fit between the brass & the inside diameter of the seater die neck area.
I did notice the Lapua brass was a little heavier/thicker than Hornady or Starline brass. Sizing it down is gonna make the case necks walls even thicker. What is the actual diameter of your 6mm mandrel? The diameter of the neck expander in my Hornady sizer die is .241". If it's larger than that, because of the thicker brass, it could cause a too tight fit between the brass & the inside diameter of the seater die neck area.
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