Yes, you are right. For double curvature member, the m-factor of 0.4 can make the buckling check less critical.
However in this case, I just wonder about a stocky member with class 1 section under uniform moment and small compression. According to the buckling check, the elastic section...
I agree that, base on common engineering principle, for stocky / bulky members the buckling won't be critical.
However, from the equations of BS5950, the buckling check (simplified method) should be at least as critical as cross-sectional check. This is where I get confused.
The same question has been posted on Stack Exchange, where the equations are written in Latex and maybe better presented.
According to clause 4.8.3.2 the cross-section capacity for non-slender section is:
Fc/(Ag py) + Mx/Mcx + My/Mcy <= 1 eqn(1)
According to clause 4.8.3.3.1 simplified...