Many of us did recycle old frames into practice material but the time it took to clean off the paint was taking away from the practice torch stuff time so speaking for myself I suggest raw tubing as a first choice. There are a lot of on line sellers of 4130 tubing. Aircraft Spruce, Stockcar Steel, McMaster-Carr, to name a few on my saved list.

I save my cut offs (sometimes called drops by the metal supply industry) for practice and small projects. I do have a box full right now and would send someone some of it (cost to be agreed on) if asked. Andy