I'm running low on H4831sc for my 300 WSM and 280 Rem and the place I get my powder from has plenty of H4831 in stock. If I switch over is it common to have to adjust the charge?
Not any more so than switching lot #'s on any powder. They have exact same burn rate but will change % of case fill at same charge weight.
i.e
80gr of H4831 = 5.800 CC's volume
80gr of H4831sc = 5.708 CC's volume.
So IF you shooting at case fill with the short cut you may have to compress (or not get as much charge in either) which can change pressures and speeds a bit.
But if your at like 90 to 99% case fill you will not see any difference other than like I stated first, no more or less than lot to lot variations with ANY powder.
So might want to follow safe practice of dropping back a couple of grains and check speed as you should anytime you change lot #'s on powder.