How do i remove rust???

[Dinosaur Jr]

Naval Jelly has always worked for me...will strip bluing though.

http://www.amazon.com/Loctite-553472-Fluid-Ounce-Dissolver/dp/B000C016OC/ref=sr_1_1?ie=UTF8&qid=1424491061&sr=8-1&keywords=navel+jelly+rust+remover

[Garand1911]

That looks like a Star model B mag, which are hard to find and pricey when you do.
I can understand taking the trouble to clean it. Cant dump those mags.