Fiberglass

Fiberglass is a composite material made from fine glass fibers bonded together with resin. The result is a lightweight, strong, and highly durable material used across industry, firearms manufacturing, and even airsoft. Fiberglass combines low weight, high tensile strength, and excellent corrosion resistance, making it an ideal material for firearm components. Thanks to its rigidity and resistance to heat and vibration, fiberglass is often used as a reinforcement for polymer parts — for example in stocks, pistol grips, handguards, and weapon frames. Fiberglass is therefore a very strong composite of glass fibers and resin. It is lightweight, durable, non-corrosive, and has a high tensile strength. It is used in firearm stocks and frames where low weight and durability are essential. In airsoft, it forms the basis of high-quality polymer gun bodies.

Why is fiberglass used in firearms?

High strength — glass fiber has higher tensile strength than most common aluminum alloys.
Impact resistance — it does not warp, does not crack, and absorbs vibration well.
Low weight — significantly lighter than metal.
Corrosion resistance — it does not rust and is unaffected by moisture.
Heat resistance — withstands heat from the barrel or suppressor.

Manufacturers of live firearms therefore use fiberglass-reinforced polymer in components such as:

rifle stocks (HK G36, Steyr AUG)
pistol grips
handguards
frames of modern carbines and pistols

Strength vs. metal alloys

Glass fiber has surprisingly high tensile strength:

Tensile strength of fiberglass: approx. 2,000–3,500 MPa
Tensile strength of common aluminum (e.g., 6061): approx. 150–300 MPa
Tensile strength of duralumin (7075-T6): approx. 500–600 MPa

This means that fiberglass is stronger than most metal alloys used in standard firearms — but its properties come from the resin matrix and the orientation of fibers. Metal, however, remains:

better for precise machining,
more resistant to point impacts,
more suitable for mechanical parts (bolt, barrel, trigger components).

For that reason, fiberglass is mostly used as a structural or outer layer, not for moving parts.

Use of fiberglass in airsoft

In airsoft, fiberglass is primarily used together with reinforced polymer:

airsoft gun bodies (polymer reinforced with fiberglass)
handguards and stocks
grips
magazines — more resistant to cracking

Well-known manufacturers using fiberglass-reinforced polymers:

G&G — their “Fiberglass Polymer” is one of the strongest on the market.
ICS — reinforced bodies for the CXP series.
Specna Arms CORE and FLEX — reinforced nylon with fiberglass content.