BRRC is a great place for you to learn more about position shooting. There are also two or three casual highpower matches of reduced course at Angeles, on the private Fort A range, every month on Saturday at 7:30am. I usually shoot them if I'm not working, and the newest addition 4th Sunday at 7:30am is very well attended by the guys who shoot at BRRC.
I fought with a websling for a while until I got it right. I put it as high up on my bicep as possible, above the pad on my jacket, then I push the cinch buckle to the very outside of my arm and crank it down. Usually is tight through a whole string, but I'm starting to play with a leather sling because it shouldn't change tension through the string.
weg: That device is obsolete now. They replaced it with wizards.
frank: Wait a minute. There are more than one wizard? Is [are?] the wizard calibrated?