I confirmed on Saturday that this was at least part of the issue, as I still wasn't getting much consistency. It all depended on where I held my head whether I could see through the scope, or had a black "ring", or saw only all black.
I knew that there are things called "cheek risers" that can raise up where your face hits on the stock, but I wasn't positive that this was the problem, nor did I want to spend a lot of money only to find out that it wasn't.
Enter Dr. LateBloomer's Redneck Solution. ( I should trademark that - LOL)
One roll of pink Duct tape
3/8ths inch poly pipe insulation - 6 feet for 97 cents at the hardware store
Viola! A temporary cheek riser, that actually worked quite well.
(Also visible in the photo is another Redneck Solution - the detergent bottle chamber flag that I posted about around Christmas time.)
The riser helped quite a bit when I went back to the range on Sunday. I realize that this is only a temporary fix, but with 6 feet of pipe insulation, I've got enough to make replacements for a couple years even, until I actually buy a real cheek riser. The only caveat is that because I am short-armed, the charging handle won't clear the riser in the position I need on the adjustable stock. Thus, if I have a jam, I'll have to move the stock position first, before using the charging handle to clear the jam.
This being a "unique snowflake" can be a real pain in the patoot! LOL