Hello, I got great groups with unique 4.1 grs with a 150 lswc. If it was me ,I'd start at 4.3grs [10 rds] and load 10 at 4.5grs for the 125gr lead. You'll may like one of these two, you may be able to go alittle higher,but I wouldnt go anylower that 4.1grs.. I dont need mag loads to shoot paper!
Hope this helps, do get a good reload manual.....