Step 2: Grip and chamber cover
For the ribbed grip section, I start with a 1.5 inch outside diameter tube of 6061 aircraft aluminum, with a one inch inside bore. With it chucked up in my lathe, I mark light tooling marks on the outside at 0.32 inch intervals so I know where my grooves will go.
When my marks are done, I begin to cut grooves.
I also leave a bit of material on the rear, so when I drill my template through that section, and cut it off, I will be left with proper holes in the grip section, and a piece of aluminum with corresponding holes I can use as a hole transfer template.