MARC Trigger Compatibility Chart: AR-15 FRD Fitment Guide
What's in this guide ▾
The MARC and MARC II are ATF-determined lawful forced reset trigger systems: one discharge per trigger pull. Both install alongside your existing fire control group, which means trigger fitment matters. This chart records our team's documented fitment experience.
Before you start: compatibility also depends on your buffer, bolt carrier group, and lower receiver. Set those with the AR-15 FRD Tuning Guide first.
The chart
Verdicts match the trigger table on the MARC and MARC II product pages. Pick a trigger to see the fitting it needs and where to buy it.
Mil-spec patternStandard loose-part fire control, including polished and enhanced mil-spec.
13 triggers · 10 drop-inDrop-in cassetteSelf-contained housing that drops in as one unit.
11 triggers · 10 drop-inPremium matchLoose-part match and two-stage triggers.
11 triggers · 2 drop-inWhy two-stage triggers need fitting
A two-stage trigger has a longer pull than a single stage. Mechanically, the tail of the trigger has to rise higher inside the lower before the hammer drops. When the tail rises too far, it contacts the bottom of the MARC's axle before the hammer can release. The symptom: the trigger breaks in semi-auto (sometimes with a heavier pull than normal), but will not break in the active-reset position.
The documented fix is removing a small amount of material from the top of the trigger tail, typically less than 0.5 mm. We will never instruct or advise anyone to modify a sear surface.
Full step-by-step fitting procedure, including what to do if the trigger stops resetting after tail relief, is in the tuning guide's "Won't reset" fix ladder.
Safety notes: read these
- Function-check on Safe frequently. Removing too much trigger-tail material can delete the surface that interfaces with the safety selector, and the weapon can become capable of firing on Safe. This is rare and only seen in extreme cases, but it has been observed. If your trigger needs material removed and a hump remains on the right (ejection-port) side of the tail, remove less material from that side. It interfaces with the safety surface.
- Trigger modification is done at your own risk. It may void the trigger manufacturer's warranty. Copperhead Safety is not responsible for damages, lack of function, loss of warranty, or unsafe firearms resulting from modifications. Individual triggers vary; the amounts described here came from our test units and yours may need more or less.
- Never modify a sear surface.
FAQ
Does the MARC II work with a stock mil-spec trigger? Most do. Mil-spec single-stage triggers on our list drop in, but CMMG and DPMS mil-spec groups are not compatible. Check the chart.
Does the MARC work with the Geissele SSA-E? Yes, with minor fitting. Most SSA-E units need light trigger-tail relief (typically under 0.5 mm, usually sanding and polishing) so the tail clears the MARC axle in the active-reset position.
Does the MARC work with the LaRue MBT-2S? Yes, with modification. The MBT-2S requires trigger-tail relief before it will run in the active-reset position, and some units also need light disconnector work.
Why won't my two-stage trigger break in the active-reset position? The trigger tail is contacting the MARC axle before the hammer can release. Small tail relief (under 0.5 mm in most documented cases) resolves it. See the fitting guide.
Will modifying my trigger make the gun unsafe? Done correctly, no, but excessive tail removal can delete the safety-interface surface. Function-check on Safe after every pass, and stop at the minimum material removal that achieves function.
Is the MARC legal? The MARC family is ATF-determined lawful: one discharge per trigger pull. State restrictions apply; see our shipping restrictions page.