So I picked up some BE-86 to load up some 147 grain Federal HST pulls I bought online. I wanted to mimic the recoil impulse of my carry ammo for training purposes and from what I've read, federal uses BE-86 or something similar for their HSTs. When looking at Alliant's load data, they list 5.1 grains as their max. I picked up federal 100 primers since they also list that on their load data as well as using federal cases. I worked loads up starting at 4.6 grains all the way up to 5.1 grains. I noticed that at 4.8 grains, the primers started to flatten slightly and by 5.0 grains they were pretty flat. My question is, are the federal 100 primers more prone to flattening because of how soft they are or is Alliant's data on the hot side? Im just curious as to why I'm seeing pressure signs below the max. Every component is the same and I'm running slightly over the recommended oal.

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