Rugged Suppressors Piston .578X28 Thread Pattern Obsidian 45 Bronze. This drastically lowers gas blowback for a more enjoyable shooting experience. Machined from 17-4 Stainless Steel and heat treated this piston is built to last. When using a piston on a fixed barrel platform such as a carbine or subgun the spring must be replaced with a Fixed Barrel Spacer. Specifications for Rugged Suppressors Piston: Manufacturer: Rugged Suppressors Color: Bronze Additional Features: Piston Features of Rugged Suppressors Piston: Non-slotted design creating a full circumference gas seal Lower gas blowback for a more enjoyable shooting experience Machined from 17-4 Stainless Steel Package Contents: Rugged Suppressors Piston