The big companies buy powder in huge lots that are NOT a powder we can buy over the counter. They work upa load that fits their velocity needs that are less than SAMMI pressure standards. It could be 8000 psi or 11,000. And the next lot will be different,could be higher or lower. French guns are well known to for the most part be hell for stout. There are handloads using Federal wads or clones and Federal hulls that are low enough pressure to meet the requirements of a 2 1/2" gun. With all the high school trap teams shooting Federal those hulls are easy to find. Good luck in your search.