What's a Good Spring Material?

Hello. First post. Nice site.

I wan't to print and assemble a magazine for my CZ 452 (22LR bolt action). I have a spring maker, and I tested it on some 302 music wire from Amazon.

I ordered some .5mm diameter wire, but what I received was about .3mm diameter. It seemed to be too squishy and wouldn't hold shape, almost trying to make a magazine spring out of a paperclip.

For those of you who made magazine springs before, what spring material did you use? Where did you get it?