+P 9mm and .45

At least in the case of Starline Brass 9mm +P brass, they note:

"Our 9MM+P has no difference from the standard 9mm Luger other than headstamp designation for load segregation. Due to standard case design, it will handle +P pressures with no problems."

I'm uncertain in the case of other brands of brass, so I'd like to see what more knowledgeable members say.

Your question is blanket but the answer is not. Can one safely load 62kpsi loads in 223 brass? Not all brass is the same yet some is. Starline 38 brass can safely handle 357 pressures just like their short colt brass. People shoot +p 9mm but I don't know any physical acomidation for it. Is there special brass??? I don't think so. 9mm major just makes brass junk in one loading.

For my open pistols I use regular 9mm brass and make major PF, I do use SRP.