I have achieved insertion

Oh behave! Things were learned and I'll probably scrap this prototype piece. I don't think cutting the big angle on it was necessary, what seemed to be the hold up was the corners in the bolt slot aren't sharp, they're rounded, so I had to likewise round off the corners on the bolt handle. I have two bolts and tested it in both. In one it was a really nice fit, too bad this bolt is non-functional otherwise I'd use the prototype in it. In the other bolt that I am using now, the fit was sloppy like the OEM. There's some tolerance variation in the bolt bodies so at least with what I did to the prototype a good result is not guaranteed. I'd want to custom fit to each individual bolt rather than machine to a general spec that fits all, ideally. I have another two blanks ready for milling, I did three up when I was doing the lathe work. I'll do the next one a little different and see if it fits both bolts better with the changes.