Type: Double Action
Caliber: .357 Magnum, .38 Special
Barrel length: 76 mm, 102 mm or 152 mm
Capacity: 6 rounds
Weight: ca. 1000-1300 g

The Ruger GP-100 series revolvers are manufactured by Sturm, Ruger & Co company of USA since 1985 or so. The GP-100 model replaced in production the erlier Ruger Security-Six and Ruger Service-Six revolvers.

All GP-100 series revolvers are all steel, six round, swing-out cylinder, double action revolvers. All models chambered for .357 magnum round featured fully underlugged barrels, some models chamberd for .38 Special featured short underbarrel lug around extractor rod. All GP-100 revolvers had following design features:

firing pin, mounted into frame, with transfer bar safety, which allows the hammer to strike the firing pin only when the trigger is completely pressed
coiled main spring
trigger mechanism mounted into single unit complete with triggerguard, which is easily removable at once for maintenance
dual cylinder crane lock, operated by pushbutton on the left recoil plate. One lock is located behind cylinder and locks the ejector rod/cylinder axis, another lock is located inside the crane and locks the crane to the front part of the frame. The forward lock is operated automatically with rear lock.
The butt part of the frame is completely enclosed inside the grips, which are made from synthetic resin with wooden sideplate inserts.
The GP-100 series revolvers available in blued steel or in stainless steel (marked with first letter K, such as KGP-141, KGP-161, for example), and with ajustable or fixed rear sights (the latter are marked with last letter F, such as KGPF-331, for example).

All GP-100 series revolvers are extremely durable and reliable, and moderately priced