What makes this BCG different from a standard mil-spec BCG?

Three things. First, the Rainbow PVD finish — a Physical Vapor Deposition coating process that produces the iridescent color and adds a harder wear surface than standard phosphate. Second, high polished components — every surface is polished before PVD coating, giving the BCG a mirror quality that standard BCGs don't have. Third, Carpenter 158 steel bolt — the original mil-spec bolt alloy, magnetic particle inspected. Everything else — M16 cut, mil-spec gas rings, mil-spec O-ring, 4140 cam pin, 8740 firing pin — runs to standard mil-spec.

Is the Trigger Supply Rainbow PVD BCG made in the USA?

Yes. The Trigger Supply Rainbow PVD BCG is 100% USA made.

Trigger Supply Rainbow PVD BCG | High Polish AR-15 Bolt Carrier Group | USA Made

Q: What steel is the bolt made from?

The bolt is machined from Carpenter 158 steel — the original mil-spec bolt steel specified by the US military for M16 and AR-15 bolts. Carpenter 158 is a chrome-moly-vanadium alloy specifically formulated for bolt lugs under the stress of repeated firing cycles. Every bolt is magnetic particle inspected (MPI) for internal defects before leaving the factory.

Q: Is this BCG M16 cut?

Yes. The Trigger Supply Rainbow PVD BCG uses an M16 full auto cut carrier profile. In a semi-auto lower it functions identically to a standard BCG — the M16 cut adds mass for smoother, more reliable cycling without any legal concerns. Compatible with all mil-spec AR-15 uppers.

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Trigger Supply · Rainbow PVD · High Polish · M16 Cut · Carpenter 158 · MPI · USA Made

The Trigger Supply Rainbow PVD BCG is the build piece that makes your AR-15 stand out without sacrificing anything on reliability. Physical Vapor Deposition coating over high-polished components produces the iridescent rainbow finish — every unit catches light differently. Under that finish is a fully spec'd Carpenter 158 steel bolt, M16 cut carrier, mil-spec gas rings and O-ring, and magnetic particle inspection on every bolt before it ships.

It looks like nothing else on the market. It runs like a mil-spec BCG should.

What Makes It Different

Rainbow PVD Finish

Physical Vapor Deposition deposits an extremely thin, molecularly bonded coating that produces the iridescent rainbow color. Harder than phosphate, does not chip or peel. The finish is applied over high-polished components — the polish is what gives the reflection, the PVD is what gives the color and durability.

High Polished Components

Every carrier and bolt surface is polished before PVD coating. The result is a mirror-quality finish that no standard BCG produces. High polish also reduces friction at contact surfaces for smoother cycling — form and function together.

Features

Rainbow PVD finish — Physical Vapor Deposition iridescent coating over high-polished components. Harder than phosphate, bonds at molecular level
Carpenter 158 steel bolt — the original mil-spec bolt alloy specified by the US military. Chrome-moly-vanadium formulated specifically for bolt lugs under repeated firing stress
Magnetic particle inspected (MPI) — every bolt inspected for internal defects before leaving the factory. The most reliable non-destructive testing method for bolt integrity
M16 full auto cut carrier — heavier carrier profile for smoother, more reliable cycling. Functions as standard semi-auto in any mil-spec lower
Mil-spec gas rings — standard mil-spec gas ring set for consistent gas seal and reliable cycling
Mil-spec O-ring — standard mil-spec O-ring for gas retention
8740 steel firing pin — hard chrome finish — high-strength firing pin alloy with hard chrome plating for long-term durability
4140 steel cam pin and extractor — standard mil-spec alloys for both components
100% USA made — all components manufactured domestically

Component Steel Breakdown

Carrier

9310 Steel — Rainbow PVD finish over high polish

Bolt

Carpenter 158 Steel — MPI tested, Rainbow PVD finish

Firing Pin

8740 Steel — hard chrome finish

Cam Pin

4140 Steel — mil-spec

Extractor

4140 Steel — mil-spec

Gas Rings

Mil-spec — standard ring set

O-Ring

Mil-spec

Full Specs

Caliber	.223 Rem / 5.56 NATO
Carrier Profile	M16 Full Auto Cut
Finish	Rainbow PVD over High Polish
Carrier Material	9310 Steel
Bolt Material	Carpenter 158 Steel
Extractor Material	4140 Steel
Cam Pin Material	4140 Steel
Firing Pin Material	8740 Steel — Hard Chrome Finish
Gas Rings	Mil-Spec
O-Ring	Mil-Spec
Inspection	Magnetic Particle Inspected (MPI)
Platform	AR-15 — all mil-spec uppers
Country of Origin	100% USA Made

Looking for Utility Over Aesthetics?

The Trigger Supply M16 Full Auto Cut BCG ($149.99) is the workhorse option — same M16 cut, USA made, built specifically for FRT builds. The KAK Industry DBC K-SPEC BCG ($199.99) is the first BCG engineered specifically for forced reset triggers with a patented dead-blow weight system.

Frequently Asked Questions

What is PVD finish on an AR-15 BCG?

PVD stands for Physical Vapor Deposition — a vacuum coating process that deposits an extremely thin, hard layer of material onto the surface of the BCG. PVD produces the rainbow iridescent color while adding a harder, more wear-resistant surface than standard phosphate or nitride. The high polish preparation before PVD gives the finish its mirror-like reflective quality.

What steel is the bolt made from?

Carpenter 158 steel — the original mil-spec bolt alloy specified by the US military for M16 and AR-15 bolts. It is a chrome-moly-vanadium alloy specifically formulated for bolt lug stress under repeated firing cycles. Every bolt is magnetic particle inspected (MPI) for internal defects before leaving the factory.

Is this BCG M16 cut?

Yes. M16 full auto cut carrier profile. In a semi-auto lower it functions identically to a standard BCG — the M16 cut adds mass for smoother, more reliable cycling. Compatible with all mil-spec AR-15 uppers. Legal in all 50 states in semi-auto builds.

Will the rainbow PVD finish hold up under hard use?

PVD is one of the hardest surface coatings available for firearm components — harder than phosphate and comparable to nitride. It bonds at a molecular level and does not chip or peel like paint. The rainbow color remains vibrant under normal use and cleaning. Like all BCG finishes, sustained high round counts and harsh cleaning chemicals will show wear over time.

What makes this different from a standard mil-spec BCG?

Three things: Rainbow PVD finish over high-polished components, Carpenter 158 steel bolt (the original mil-spec alloy), and magnetic particle inspection on every bolt. Everything else — M16 cut, mil-spec gas rings, mil-spec O-ring, 4140 cam pin, 8740 firing pin — runs to standard mil-spec tolerances.

Is this made in the USA?

Yes. 100% USA made.

Related Products

It is the buyer's responsibility to comply with all applicable local, state, and federal laws regarding firearm parts and accessories. Install by a qualified individual familiar with AR-15 platforms. Trigger Supply is a brand of TTT Innovations. 100% USA made.

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