Rocket Airsoft Pro-1 M4 Metal Hopup Chamber 6mm (0.23-0.66g) so no heavy modification is

so no heavy modification is needed to change its stock

We sell more of these in our storefront than any other vest simply because they look great

and a 14mm threaded outer barrel for muzzle brakes

steel gears

Rocket Airsoft Pro-1 M4 Metal Hopup Chamber 6mm (0.23-0.66g) so no heavy modification isThe Rocket Airsoft Pro 1 M4 Metal Hopup Chamber is an advanced design similar to the Prowin, but with a different cut and some extra parts included. Clean and aluminum make will fit in all M4 AEG airsoft guns' gearboxes. Includes SHS rubber bucking, but we recommend another bucking, such as a Maple Leaf, sold separately. Great for HPA gun installs! Packaging is Rocket Airsoft (OEM SHS).