Milspec Active Reset Conversion (MARC)
Copperhead Safety Cornfire Arsenal Ambidextrous forced reset trigger for AR-15. The MARC features an S7 tool steel lever, 4140 selector, and three-position milspec operation drop-in compatible, easy to install and built to duty-use tolerances.
The Milspec Active Reset Conversion — available in standard and ambidextrous configurations — is a three-position forced reset trigger system built to the tolerances and material standards we demand in our own rifles. Clone-correct geometry, S7 tool steel lever, 4140 selector lever. No compromises in the bill of materials, no untested configurations shipped to customers.
Product Features
- S7 Tool Steel Lever — properly heat treated and nitride coated for superior wear resistance and surface hardness under repeated cycling
- 4140 Steel Selector Lever — mil-spec material selection throughout, no substitutions
- Engineered Interaction Surfaces — precise dimensional control on all mating surfaces, specifically designed to prevent binding against the trigger during hammer reset
- Rounded Edges — all lever edges are radiused to prevent stress concentration and crack initiation under load
- Three-Position Operation — standard semi, enhanced semi, and full reset modes
- Ambidextrous Configuration Available — increased control surface access for both left and right-handed operators; right-handed shooters may find the additional surface area beneficial for rapid mode transitions
- Clone-Correct Profile — designed to mil-spec geometry for drop-in compatibility with standard lower receivers
FRT Requirements Checklist
Sufficient Buffer Weight — your rifle must run a heavy enough buffer to prevent bolt bounce. Bolt bounce causes dead trigger and light primer strikes. If you experience either, increase buffer weight before anything else. See tuning recommendations below.
M16-Cut Bolt Carrier Group (BCG) — required for proper hammer reset cycling. Standard BCGs will not function correctly.
Low-Shelf Lower Receiver — required. Users must either have a low-shelf lower or be comfortable modifying their existing lower to low-shelf configuration.
Geissele Over Travel Stop — required only if running a Geissele trigger. Available separately from Copperhead Safety.
Standard Test Configurations
Standard carbine buffer tube · carbine spring · H2 buffer
A5 buffer tube · A5 spring · H1 buffer
Tuning Recommendations
Based on our personal test configurations. Results may vary depending on your specific build.
| Caliber | Barrel Length | Gas System | Suppressed | Recommended Buffer |
|---|---|---|---|---|
| 5.56 | 16" | Mid-Length | No | H1 / H2 |
| 5.56 | 16" | Mid-Length | Yes | H2 / H3 |
| 5.56 | 16" | Carbine-Length | No | H2 / H3 or Rifle Spring + Carbine Buffer |
| 5.56 | 11.5" | Carbine-Length | No | H1 / H2 |
| 5.56 | 11.5" | Carbine-Length | Yes | H2 / H3 |
| 300 BLK | 7.5" | Pistol-Length | No | H1 |
| 300 BLK | 7.5" | Pistol-Length | Yes | H1 / H2 |
Trigger Compatibility
This list is not exhaustive. Inclusion or omission does not guarantee compatibility in every configuration — variables in individual builds may affect results.
| Brand | Model | Type | Compatible |
|---|---|---|---|
| Geissele | SSA | Two Stage | YES * |
| Geissele | SSA-E | Two Stage | YES * |
| Geissele | S3G | Single Stage | YES |
| Geissele | SD3G | Single Stage | YES |
| Geissele | G2S | Two Stage | YES * |
| Geissele | SD-E | Two Stage | YES * |
| Geissele | SSAEX | Two Stage | MODIFICATION REQUIRED |
| Geissele | SSAX | Two Stage | MODIFICATION REQUIRED |
| LaRue | MBT-2S (Flat & Curved) | Two Stage | MODIFICATION REQUIRED |
| CMMG | Milspec | Single Stage | NO |
| DPMS | Milspec | Single Stage | NO |
| Jacob Gray | Single Stage | Single Stage | YES |
| MimTac | MimTac Drastic | Single Stage | YES |
| Noveske | Single Stage | Single Stage | YES |
| PSA | EPT | Single Stage | YES |
| PSA | Custom SS Drop-In | Single Stage | YES |
| Rise Armament | Rave 140 | Single Stage | YES |
| Rise Armament | RA-434 | Single Stage | YES |
| Rise Armament | RA-535 | Single Stage | YES |
| Rise Armament | RA Blitz | Single Stage | YES |
| Rise Armament | RA LE145 | Single Stage | YES |
| Rise Armament | ICONIC | Two Stage | NO |
| Schmid Inside | Two-Stage | Two Stage | MODIFICATION REQUIRED |
| Schmid Inside | Pro Line | Single Stage | YES |
| Schmid Inside | GI Flat Face SS | Single Stage | YES |
| Schmid Inside | Match Flat Face SS | Single Stage | YES |
| Smith Defense | AR-15 LPK | Single Stage | YES |
| Sons of Liberty Gun Works | SOLGW LFT | Single Stage | YES |
| Spikes Tactical | ST Battle | Single Stage | YES |
| Timney | Competition 3LB | Single Stage | YES |
| Timney | Calvin Elite | Single Stage | YES |
| Heckler & Koch | HK MR556A1 | Single Stage | NO |
* Geissele two-stage triggers marked YES may require minor polishing or small material removal on the top of the trigger shoe tail due to increased travel distance and tolerance stacking. See installation guide for details.
Firearm Functionality
This product, when properly installed and left unmodified, is designed and intended solely for lawful semi-automatic operation. It is not capable of automatic fire, nor is it readily convertible to enable automatic or burst-fire operation. The MARC actively resets the trigger, producing one discharge per individual trigger pull, in full compliance with applicable federal firearm law. End users are responsible for understanding and complying with all state and local regulations applicable to their jurisdiction.
ATF FRT Legal Determination →Intellectual Property
The MARC operates on general mechanical principles consistent with those recognized as lawful in prior judicial and regulatory determinations. It does not use, reproduce, or infringe upon any patented, copyrighted, or otherwise protected intellectual property belonging to any third party.
The trigger group interaction and reset system were developed entirely in-house, without access to or use of any competitor's CAD files, proprietary data, or patent-protected materials. The MARC incorporates distinct mechanical geometry, material composition, and sequencing that result in substantial design deviations, reflecting independent engineering judgment and upgraded material selection.
The mechanical act of resetting a trigger or releasing a hammer at defined points in an operational cycle represents a functional process within the public domain and is not subject to copyright protection. The MARC features aesthetically distinct components — including a modified mil-spec safety selector profile and externally visible differences — providing clear differentiation in both form and trade dress.
Inquiries
Copperhead Safety LLC is committed to transparency and good-faith communication. Any individual or entity with questions or concerns regarding the design, function, or legality of our products is encouraged to contact us prior to pursuing legal action.
Contact: admin@copperheadsafety.com
