Here is a rifle dad built back in the mid 1970's It has a hand cut cherry stock and a Federal Ord receiver. As you can see from the photos it is a custom M1 Garand. I will let you look at the photo of of the loaded enbloc and see if you can figure out what cartridge it is. It is wildcat and not commercially available.
The scope is just a straight 10X Tasco Scope. I have had this rifle for several years and have never pulled the trigger on it until today. I ended up having to reduce the load by 10% that I use in my bold guns, because the port pressure was a bit high. Even with the load reduced by 10% I am still zipping along at 3700 fps. Now that I have a load that will work the action and not yank the rims off of the case I can zero the rifle and work up an accuracy load. Should be fun.