Dobson
In most cases I would say don't use them but with primers being somewhat hard to find these days you may not have a choice , that being said , you will need to go back to a starting load for sure and work back up to were you want to be .
The mag primer may have a much hotter spark causing more pressure so backing off " a wee bit " just an't going to cut it , as with any componant change you should start from zero and work up again .
stimpy
ANYTIME you change
ANY component in a reload, you should "start over", as Stimpy indicated. You might "short-cut" it by starting with a 5% reduction from the "maximum load", but to error on the
SAFE side is not a bad thing, you should reduce the Max load 10% and work up to the most accurate load again.
CAUTION: If you are using H-110 powder, Hodgdon indicates you should not reduce the load more than 3% !!!I really don't know whether the magnum primers are "hotter" than a standard primer or not... but, generally, with almost a HALF CENTURY of reloading behind me, I've generally found that magnum primers either make little or no difference in apparent presure, but tend to be
less accurate than standard primers in most loads.
Strength & Honor...
Ron T.