Flintski,
I have been watching this thread and thought I would jump in. I think that you would be surprised at the number of silhouette shooters have used an semi-auto over the years. In fact, I do believe that nationals has been won with a semi-atuo.
The biggest disadvantage that people find with the semi-auto is its unique recoil. Most people find a semi-autos recoil to be distracting during the follow through phase of the shot. However, I think that if you can learn a good follow through on a semi-auto you can have an awesome follow through on a bolt action.
There are a few manufacturers making competitive semi-auto's for silhouette. For example Brielly, Volquartsen, Clark... they are great rifles, and as every bit as competitive as a bolt action.
Most silhouette shooters try to find the equipment that is the easiest to shoot, or has the easiest learning curve. So bolt actions have been more prevalant. However, auto's have some very unique qualites, such as not having to put the gun down between shots. This can help in windy conditions or during times of good holding.
If you are shooting in Utah, the Anschutz and Cz is very prevalent. Don't let anybody tell you that it is the only way to go. Shoot a while, and determine what your shooting style needs. I remember when all of the Utah shooters bought the ruger 77/22 synthetic style rifles, and swore by it. They are a trendy bunch and seem to have moved on to the CZ. The CZ is a great gun, and will take you to the master class with some practice.
As far as scopes go, take a look at a Sightron SII, bushnell Elite 4200, or a Weaver V.24. These are the cheaper alternatives to the Leupold Var III EFR models. I know that locally Kent Shooters SUpply and Sportsmans Warehouse carry them.
There has been lots of good info on this thread, the biggest thing is to use what you have until you are certain on what exactly you want out of your equipment.
C Hunter