I direct thread my theorem on my 18” AR.
Results are awesome 1/2 moa @100.
Waiting to get my biscuit out of jail.
Abel’s machining is awesome compared to a couple other high end can manufacturers.
Size is something you will have to decide. I made one with a scrap piece of aluminum I had in my scrap metal pile. I had all the stuff to make it. Turned out decent for about an hours time.