Dream,
You are a lucky man, if my wife got me an adjustable stock for one of my guns, she would have used one of my credit cards.
Size of face (Cheek bone), lenigh of neck, and shoulder will all impact fit. Plus the position of your feet, knees, and hips will also effect your scores.
Don't worry about one bad round, or even a whole match. As you shoot, they will become fewer & fewer, and farther apart.
Do you reload your own? Reloading had the biggest impact on my shooting. I would shoot a whole box from station 1 before moving on, then a whole box at station 2, and so on & so on, intill I had shot 125 rounds. Sometimes I would ask the guy running the range to lock the thrower in one position, and then shoot a complete round of "Hard Rights" from all stations, or maybe just station 5. The same with station 1 & "Hard Lefts".
Just keep your head down, and don't stop your swing, its a piece of "Cake"
