As long as the paint isnt something permanent, like Aluma Hyde II, or something similar (Krylon "Fusion" might also be an issue with the polymers), Gun Scrubber, Hoppes, or a similar solvent, along with a toothbrush, or similar, thats on the stiffer side, should get most of it off pretty quickly. Dental type picks, patches, Q Tips, etc, are some other items that will make things easier.
It will likely take a little work, but from my experience, it will come off, and come off completely.
Your best results are going to be if you strip the frame and clean it, and the individual parts, separately. I think that will make things easier and will give you a better job.