armor. Gw. St. G. 58: Anti-personnel fragmentation with impact detonator (direct or indirect-fire). Gw. Nb. G. 58: Smoke canister for reducing visibility (direct or indirect-fire). Gw. UG 58: Practice (inert orange rubber), with or without booster charge. Accuracy potential The following tables list accuracy statistics for typical in service Stgw. 57 rifles firing 7.5×55mm Swiss GP 11 service ammunition obtained by average marksman. The statistics were computed under the 1950's Swiss method for determining accuracy, which is more complex than Western methods which usually involve firing a group of shots and then measuring the overall diameter of the group. The Swiss method differs in that after a group of shots is fired into the target from a machine rest hits on the outer part of the target are disregarded, while only half of the hits on the inner part of the circles are counted (50% or R50), which significantly reduces the overall diameter of the groups. The vertical and horizontal measurements of the reduced groups are then used to measure accuracy. This circular error probable method used by the Swiss and other European militaries cannot be converted and is not comparable to US military methods for determining rifle accuracy. When the R50 results are doubled the hit probability increases to 93.7%. R50 means the closest 50 percent of the shot group will all be within a circle of the mentioned diameter. R93.7 means the closest 93.7 percent of the shot group will all be within a circle of the mentioned diameter. The single shot dispersion was determined from the bipod in the rear position. The 4-6 shot sort burst dispersion determined from the more stable bipod at the front position. For reference a 1 minute of arc (MOA) circle at has a diameter of and at has a diameter of . The radius of a circle is half its diameter. Civilian use Upon completion of their military service, members of the Swiss armed forces could obtain ownership of their personal Stgw. 57 rifle by paying an administrative fee. These "civilianised" Stgw. 57 rifles were converted to a semi-automatic only configuration. Dedicated factory-built, semi-automatic only rifles for private purchase were available and designated PE-Stgw. 57, PE means Privat Einzelfeuer ("private single fire"). These civilian rifles incorporate subtle design changes to avoid some cross-compatibility with army rifle parts. As of 2007, around 40 percent of discharged soldiers choose to retain their weapon