George,
Noticed that you list your location as Central Arkansas. I shoot out of the Old Fort Gun Club at Fort Smith, AR and there are several excellent silhouette shooters that shoot out of the Benton Gun Club near Benton Arkansas, which of course is located in the central part of the state. The guys down at Benton are some of the most knowledgeable and helpful that you will find anywhere and, while I can't speak for them, I'd be willing to bet that some of them would be willing to work with you on form. If you are near enought to Fort Smith I would be more than happy to give you any help you might need.
As far a books go, one of the most helpful discussions about hold, natural point of aim, etc that I have read is in David Tubb's book High Power Rifle. Hope this helps. Feel free to PM me or email me at jneihouse@earthlink.net if I can be of any help
John Neihouse