Great post Forrest -- thanks!
Originally Posted by Forrest Addy
By the way, I cheat and use Cerro-Safe. It's a Bismuth alloy that's very similar to Cerro-bend ("fixturing alloy"). A lot of gunsmiths use it to measure chamber bores -- it's about $14/lb, but you only need about 4 ounces. McMaster carries it.
You heat it to 180* (hot water), pour the melted Cerro-Safe in the threaded region, let it cool for 15 minutes, and unscrew. Let it settle for 30 minutes, and then you have a perfect impression of the internal threads.
"Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."