Dimensions & WeightOverall Length: ~3.55 inches (approx. 90 mm) from the bolt face to the tail.Stem Diameter: ~0.43 inches (approx. 11 mm) on a standard AKM pattern.Weight: ~2.6 to 3.0 ounces (fully assembled with firing pin and extractor).Material & ConstructionSteel Grade: Generally milled from 8620 or 9310 alloy steel forgings, or forged 4140/4340 chromoly steel.Hardness: Heat-treated to a rockwell hardness of roughly Rc 42 to Rc 48 to withstand explosive chamber pressures without deforming.Finish: Black phosphate (parkerized), black oxide, or left in the polished white (common on older European surplus).Mechanical FeaturesLocking Lugs: Dual opposed locking lugs that rotate roughly 35 degrees inside the trunnion to lock the breech.Bolt Face: Counter-bored circle with an integrated recess depth of roughly 0.115 inches to hold the 7.62x39mm cartridge rim snugly.Firing Pin Channel: Straight through-bore, designed for a free-floating or spring-reset triangular/cylindrical firing pin.