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Atrius Mil Spec Ambi Foced Reset Selector

$254.00

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Product Code: atrius-milspec-ambi Categories: , , , , Brand:

Ambidextrous Atrius forced reset selector with a mil-spec style switch on both sides. Requires a full-profile (M16) bolt carrier, an H2 or H3 buffer and a trigger without a relief cut. No FFL — ships to your door where legal.

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Product Description

The Atrius Mil-Spec Ambi Forced Reset Selector is Atrius’s ambidextrous forced reset selector (“super safety”) with a traditional mil-spec style switch and a position pointer on both sides of the rifle. It drops into a standard AR-15 in place of your safety selector and gives you three positions: Safe, Semi and Super-Semi. In the third position it forces your existing trigger to reset after every shot. It ships to your door with no FFL.

  • What it is: an ambidextrous 3-position forced reset selector for the AR-15: Safe / Semi / Super-Semi.
  • Trigger compatibility: mil-spec triggers without a relief cut (U-notch), and single-stage drop-in cassette triggers such as Rise Armament, per Atrius.
  • What your rifle needs: a full-profile (M16) bolt carrier, an H2 or H3 buffer, a low-shelf or full-profile lower and a carbine-length buffer tube.
  • Build: heat-treated 4140 steel, corrosion-resistant black nitride, mil-spec style ridged switch with a pointer on each side. Ships in an Atrius M81 camo bag.
  • Rounds per pull: one, in every firing position.
  • Ordering: a part, not a firearm. No FFL, ships to your door in states we can ship to.

Who the Mil-Spec Ambi is for

Choose this model if you shoot left-handed, train to run the safety with either thumb, or simply want a selector that looks and feels like a standard mil-spec ambi safety. Functionally it does the same job as the single-sided Atrius Forced Reset Selector; the difference is the lever on both sides and the traditional switch shape. Geissele SSA, SSA-E and G2S owners should look at the Atrius G-Lever instead.

How it works

In Safe and Semi it behaves like any AR-15 selector. In Super-Semi, a cam on the selector shaft uses the hammer’s rearward travel as the bolt carrier cycles to push your trigger forward to its reset point. Keep pressure on the trigger and it is ready again almost at once. You still pull the trigger for every round.

Compatibility checklist

Trigger Mil-spec trigger with a squared-off trigger bar, or a compatible single-stage drop-in cassette. Not triggers with a U-notch or relief cut.
Lower receiver Low-shelf or full-profile trigger pocket. Not high-shelf lowers.
Bolt carrier group Full-profile (M16) BCG required
Buffer H2 or H3
Buffer tube Carbine length; pistol-length tubes are not compatible
Calibers .223 / 5.56 NATO and .300 Blackout AR-15s
Not for AR-10 / SR-25 without significant gunsmithing; AR-9 may need a gunsmith
Lever screws T10, 4-40; Atrius recommends 15 in-lb with blue thread locker

Pair it with an M16-profile bolt carrier from Rankin Industries, Daniel Defense or Faxon, and an H2 or H3 buffer from our buffers and buffer tube kits.

Installation in brief

Unload the rifle, remove the pistol grip, selector spring and detent, take out the old selector, install the Atrius detent shaft and cam lever, reinstall the grip and fit both levers with the T10 screws. No buffer tube removal. Run the binding test and a full function check before live fire. See the full steps in our Atrius forced reset selector guide.

Compare Atrius forced reset selectors

Model Levers Choose it for
Atrius Mil-Spec Ambi (this page) Ambidextrous, mil-spec style with pointers Left-handed shooters and a traditional look
Atrius Forced Reset Selector Single-sided, ergonomic The lowest-cost Atrius model
Atrius G-Lever Ambi Ambidextrous Geissele SSA, SSA-E and G2S triggers
Ambi 3-Position Forced Reset Selector Ambidextrous Our own unbranded two-sided option (not an Atrius product)

Browse every forced reset trigger and selector, or compare styles in super safety vs FRT.

How ordering works

Western Sport has been a licensed FFL/SOT dealer since 2007. This selector is a part, so it ships to your door with no FFL transfer. When it shows as available on backorder, you can still order and we will ship as soon as Atrius stock arrives. Every address is checked against our restricted-state list before it ships. Questions? Send us a message.

Shipping Restrictions

This item ships to most U.S. states. State and local laws on forced-reset and rapid-fire devices vary and continue to change, so we do not ship this product to any state or jurisdiction where its legality is restricted, disputed, or dependent on the carrier. The list below is deliberately conservative: if there is meaningful risk, we do not ship there.

States and jurisdictions we do not ship to

  • California
  • Colorado
  • Connecticut
  • Delaware
  • District of Columbia
  • Florida
  • Hawaii
  • Illinois
  • Iowa
  • Maryland
  • Massachusetts
  • Minnesota
  • Nevada
  • New Jersey
  • New York
  • Oregon
  • Rhode Island
  • Virginia
  • Washington
  • U.S. territories
  • International destinations

Florida and Minnesota restrict retail sales of these devices, and shipments into Iowa and Virginia depend on carrier and distributor policy rather than on a settled rule. We treat all four as no-ship states. Municipal bans such as Chicago, Illinois and Denver, Colorado sit inside states already on the list above.

State statutes and retail shipping policies change frequently. Always verify current local legislation and consult legal counsel prior to shipping. If you are not sure whether we can ship to your address, send us a message before you order and we will tell you before we take your money.

Atrius Mil-Spec Ambi FAQ

What is the difference between the Atrius Mil-Spec Ambi and the standard Atrius FRS?

Both are 3-position forced reset selectors with the same internal function. The Mil-Spec Ambi has a mil-spec style switch with a position pointer on both sides of the rifle; the standard Atrius Forced Reset Selector is single-sided with Atrius’s ergonomic switch.

Does the Atrius ambidextrous forced reset selector work with drop-in triggers?

Atrius lists single-stage drop-in cassette triggers, such as Rise Armament, as compatible, along with mil-spec triggers that do not have a relief cut or U-notch. For Geissele SSA, SSA-E and G2S triggers, use the Atrius G-Lever.

Does it need an M16 bolt carrier?

Yes. Atrius requires a full-profile (M16) bolt carrier group and an H2 or H3 buffer.

Will it work in an AR pistol?

Only if the pistol uses a carbine-length buffer tube. Atrius says pistol-length tubes are not compatible.

Is the Atrius Mil-Spec Ambi legal?

It fires one round per function of the trigger, and forced reset devices that do so are not being treated as machine guns at the federal level after the May 2025 DOJ settlement with Rare Breed Triggers. Several states restrict them; we do not ship to CA, CO, CT, DE, DC, FL, HI, IL, IA, MD, MA, MN, NV, NJ, NY, OR, RI, VA or WA. This is not legal advice.

Specifications and compatibility from Atrius Development Group. Western Sport is a retailer, not the manufacturer.

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