The R93 aside, a few points on the R8. (MINUTIA) Barrel Lengths: Blaser list their barrels with overall lengths, from tip of muzzle to very end of breach opening. Barrel lengths measured from bolt face to muzzle is about 2cm less or somewhere between 3/4 to 7/8th's of an inch. Iron Sights: If you have std. iron sights on your barrel then the rear sight can be adjusted for windage and the front sight adjusted for elevation. The Selous barrels have a rear leaf sight that can be adjusted for windage but the front sight is non adjustable requiring either a different height insert or filing the leaf sight if POI is too low. Fire Control Group & Magazines: The R8's fire control group is designed to be removed from the stock for changing out magazines and/or loading cartridges. Cartridges can also be top loaded. When the fire control group is removed from the stock/receiver the safety automatically engages. Magazines are somewhat caliber specific. Since in general magnum length cartridges are longer than say short action cartridges you will have a difference in the way they feed and in the distance the bolt cycles. Blaser takes that into consideration with their magazines, controlling both the feed angle and bolt throw.