Last things first..
The Blaser comes with a T handle allen wrench which is the only thing you need to switch barrels.
The gun is built around the barrel, so Blaser likes to think of you adding the stock, recvier, etc... to the barrel. This shift in focus from the receiver to the barrel is what makes the transition so easy. This also influences the issue of the accuracy from one barrel to the next. This is going to get kinda hard to follow: Think about a traditional rifle, like a Ruger M-77 or a rem mdl 700. If you have one, go get it. Okay, now open the bolt (or think about it) picture the gun without the barrel. See how there is still some of the receiver left infront of the ejection port? this is where the scope is often mounted (or at least one of the rings is usually there) If you attach a new barrel to that reciever you are going to have to change the scope, etc. That barrel may also mate up with the recievere differently.
now, back to the Blaser. The Blaser doesn't have that "front part" of the recevier. The "back half" of the reciever attaches to the stock. This includes the part that moves, which mounts to the lower half rather like a 1911 slide mounts to a frame, in other words it is not the bolt being pulled through a receiver, rather, the whole receiver top with the bolt face is pulled backwards to work the action. Just in front of the two pieces of the receiver is the magazine, which uses a few different inserts, depending on the round being used. Now, you add the barrel to the equation, which is attached to the stock in front of the magazine. On the Blaser, the scope is mounted to the barrel itself so there is no change in that relationship. Also, the barrels relationship to the stock is as constant as modern manufacturing allows (pretty damn constant...) The boltfaces are particular to the round being used and have a 360 degree lock up and push the round into the chamber the same way for every barrel. all of this consitency, with the key factor being that the barrel is really the heart of the rifle result in some the Blaser's almost unique ability to change calibres without changing the feel of your rifle, nor compromising its ability to perform as an outstanding rifle in any of the calibres. In fact, in Europe, the fact that the Blaser's barrels can be changed is often an afterthought. The R-93 is the gun of the hunting elite in Europe and most of them can afford to buy as many rifles as they need, it is not uncommon for people to have more than one complete Blaser over there. (lazy continentas!)
Whew.. that said, as far as benchrest accuracy goes, I cannot make a statement until I have some serious time for testing it out. So I will reserve comment.
The CISM issue goes back to what I was talking about with rifle being built around the barrel. So, Although I am not familar with the internal workings of the CISM platform, I can only assume that the stock could be added to any Blaser Barrel.
sorry for the length...
