Hello: To start with I use 142 gr. SMK for fireforming and regular loads and both at COL = 3.445". The first time I had used 54.0 gr. H4831SC to fireform my 6.5 Gibbs and it was too hot. It made the primer pockets just a little bit loose. I dropped down to 52.0 gr. H4831SC for fireforming...