How are people losing the bumps on their mags for their prototype builds?

I have, to save originals,  converted DPMS 308 mags to work in original AR10s. To get rid of the bunp  disassemble the mag, block the inside, I used some high speed steel tooling. Of the methods I tried heat, C clamp, vise, brass drift, BFH, and combinations of each, brass drift and a big hammer cold worked the best with the least finish marks. Those mags however are steel, the aluminum might be as easy as blocking the inside, some heat and a C clamp.

You have pretty much three options.  A steel Costa Mesa 30 round full curve AR180 mag does not have a bump, and they work perfectly.  Another option is to build a prototype 25 round mag.  The instructions how to do this are in retroblackrifle.com If you go this route, and want to use the mag, you will need to weld the mags together instead of gluing them together like the instructions suggest. Mine came out great, and works well. I've been kicking around the idea of doing a run of ten.  The last option is to place a piece of steel in the magazine, and smash the bump. This is the easiest option, and works great.  From what I understand, the waffle mags came out AFTER the prototype series was over, so I WOULD NOT modify a waffle, either real or NoDak.

Well, I was going to try and modify my NDS Waffle, but getting a piece of steel in there, between the ridges seems unlikely.

Unfortunately, anything over 10 rounds is illegal here, so I can't buy any of the originals.  And I don't have any of the tooling needed to manufacture a straight 25 myself.  I guess I could smash in some of my 30 rounders, but that just seems wrong. . .

So it seems I'm kind of SOL. . .  

Let me know if you make those 25s, and can block a couple of them up so they only take 10. . .