The GrovTec Crush Washer .308 - 5 Pack (MPN: GTHM320) provides essential mechanical hardware for installing and timing directional muzzle devices on centrefire rifles. Manufactured from high-strength steel and treated with a protective Black Nitride finish, each washer is engineered to deform plastically under applied torque. This controlled deformation allows precise rotational alignment of muzzle brakes, compensators, and flash hiders while maintaining continuous mechanical tension against the barrel shoulder to resist loosening under recoil forces. As an unregulated mechanical firearm accessory, it is fully compliant for purchase and use across all Australian states and territories.

Key Features

• Controlled Plastic Deformation: Crushes progressively as torque is applied to facilitate exact rotational timing of directional muzzle ports before reaching final installation tension.
• Black Nitride Surface Finish: Delivers enhanced surface hardness, thermal resistance, and protection against corrosion and carbon fouling accumulation.
• Constant Mechanical Tension: Secures the interface between the barrel shoulder and the muzzle device to prevent backing off during sustained firing strings.
• Multi-Piece Pack: Supplied as a 5-pack, providing sufficient single-use replacement hardware for multiple rifle builds or muzzle device swaps.

Specifications

• Brand: GrovTec US Inc.
• Model / MPN: GTHM320
• Thread Pitch: 5/8"-24 TPI
• Calibre Compatibility: .308 Winchester / 7.62mm (and related calibres sharing 5/8"-24 threads, such as 6.5 Creedmoor and .300 AAC Blackout)
• Quantity: 5 washers per pack
• Material: High-strength steel
• Finish: Black Nitride
• Lifecycle: Single-use (must be replaced upon removal)
• Package Weight: Approximately 22 g to 45 g (0.05 lbs to 0.10 lbs)

Who is the GrovTec Crush Washer .308 - 5 Pack for?

• Modern sporting rifle builders — Requires 5/8"-24 TPI thread compatibility to correctly time and mount directional muzzle brakes on .308 calibre barrel platforms.
• Precision rifle armorers — Needs a 5-pack of single-use .308 rifle muzzle device crush washers to ensure fresh, properly tensioned hardware during routine maintenance and barrel upgrades.

Less suitable for: Barrels threaded with 1/2"-28 TPI interfaces (such as standard .223 Rem / 5.56 NATO platforms), which require a 1/2"-28 specific crush washer (such as GrovTec model GTHM319), or mounting direct-thread and quick-detach suppressor adaptors, which require a precision-machined shim kit or direct shoulder mounting to prevent asymmetric deformation and non-concentric alignment.