Yes, I have designed wildcat cartridges and the reamers are available from JGS and the dies from Huntington/RCBS. I designed and had built a double NE rifle superimposed just because I wanted to try it. I designed a short 8mm magnum cartridge 20 years before Winchester came out with the .325 WSM. I hunt with that cartridge in a custom 1909 Mauser, but I suppose that stinks too since the Mauser design is over 100 years old.
Back to the original point of the thread - nice rifle! I hope Mike enjoys it.
"The Democrat Party looks like Titanic survivors. Partying and celebrating one moment, and huddled in lifeboats freezing the next". Hatari 2017
"Hokey religions and ancient weapons are no match for a good blaster at your side, kid." Han Solo
