I called Hodgdon yesterday to ask about this. The guy I spoke with said the max load used to be 120 Grains of loose powder for 50 and 54 caliber but there were problems when guys using 150 gr of loose powder blew up a gun and claimed it was due to the 3 50 gr pellet magnum loading that they publicized. So they backed it off and came out with 60 gr pellets. If you look on the box top label it states 1 pellet is equivalent to 60 gr volume. The max of 2 pellets would be a 120 gr load.

https://www.hodgdon.com/triple-seven-50-caliber-magnums-60-grain-pellets/

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