Since I'm not on the racing side of the fence, some parts of what you do I'll never understand. If you literally are removing microscopic amounts of material, then fine..

Ive seen the pinching dies on eBay and stuff... For how much I run my engines, I'd never need to get it done (re-pinching)... I've yet to wear out a P/L set in almost 20 years and that's with running 99% RTR engines on (up until about 3-4 years ago) commercially available hobby shop swill (fuel). I noticed a big (good) change in engine behavior when I started using my own fuel blends I mixed myself.