I agree with the 5.0 as max.
Lyman Cast Bullet Handbook:
124 gr Cast - Unique: 4.4 to 4.9 gr @ 30,700 c.u.p.
125 gr cast - Unique: 4.5 to 5.0 @ 30,300 c.u.p.
Approach Max Loads with caution and common sense. While this is published data, I make no claims to it's accuracy.
“At the core of liberalism is the spoiled child – miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats.” — P.J. O’Rourke