FAQs

The Atrius Forced Reset Selectors (Single-sided and Ambi) require MILSPEC triggers that have a squared off trigger bar at its rear end. Mil-spec triggers that have “U” notches and relief cuts are not compatible. Competition and cassette type triggers may or may not work due to their varying trigger bar designs. For our updated list of compatible triggers please see our product page descriptions or Compatibility Page.

Binding usually happens for 1 of 2 reasons. The cam is binding with the trigger bar OR the lever is binding with the upper itself. Here’s what you can do to test for binding: 1. With the upper off, switch the selector to the third position. Apply downward pressure on the trigger hammer. Maintain that downward pressure and check that the lever on the selector manually moves all the way to the rear take down pin and back up to the hammer. If there is any resistance or binding, the trigger bar tolerance may have varied just enough to bind with the cam. 2. If you passed binding test 1, put paint marker all around the top of your lever, put the upper receiver on. Run a dry function test. Open up the receiver and see where the paint Scratched off on the upper. If you have paint scratching on the bottom side of the rear of the upper receiver, it may binding on the excess material there.

In order for the Atrius FRS to function properly, you need to use a MILSPEC AR-15 lower receiver with a low shelf and a full profile trigger pocket. Ensure your bolt carrier group is full profile as well. If you are experiencing light strikes ensure that you are using an H2 or H3 buffer. Experimenting with different buffer springs may also help.

No brand’s manufacturing process is perfect which is why there is always some level of “tolerance”. Tolerance stacking refers to the way variations in part dimensions add up which could lead to fitment and or function issues. For the Atrius FRS, tolerances between the lower and upper receivers, trigger, bolt carrier group, and gas/buffer system all play into this and contribute to whether your weapon platform is functioning properly or not.

A high shelf receiver has a material shelf that extends upwards and is leveled with the top of the safety selector’s hole in a lower receiver. If your lower has this characteristic - it is not compatible with the Atrius FRS.
Whereas a low shelf receiver does not have that material shelf below the top of the safety selector’s hole. For our product, the lower the shelf the better!

Also known as a M16 fire control group pocket, a full profile trigger pocket refers to the space directly behind the safety selector and the trigger bar. This space is needed for clearance of the cam lever to actuate and move freely.

If you broke your lever, have no fear. Simply take a picture of your broken lever and submit a replacement ticket on our site under the Contact Us page. Please provide your order number and or a copy of your receipt if you bought our product from one of our dealers and we’ll get you a replacement mailed free of charge!

It certainly can, however, ensure that your AR pistol is using a carbine length buffer tube. Pistol length buffer tubes will render your platform incompatible with the Atrius FRS.

If your trigger is dead in the 3rd position and is unable to fire, your bolt cut may be the issue. Please be sure that you are using a full profile BCG. Otherwise you also may be using an incompatible trigger. Ensure that your trigger bar’s rear is squared off and does not have any relief cuts or a “U” shaped notch.

Check one of the casings from your malfunction to look at the primer. If you are experiencing light primer strikes changing to a H2 or H3 buffer may help aid your cycling consistency. If you are using an adjustable gas block - ensure that your rifle was properly tuned before installing the Atrius FRS as well. Spent casing ejection pattern is not 100% indicative but in general they should be ejecting towards your 4 o’clock.

Piston style AR-15’s that utilize a standard full profile BCG and carbine buffer tube should still operate with the Atrius FRS. However, bufferless rifles generally require unique bolt carrier groups that do not interface with our Selector and may require a special trip bar or other modifications to work.

No! The Atrius FRS is a drop-in solution for many MILSPEC AR-15s. In general, you can drop this product into most AR15 rifles without any issue. However, if you have a custom or specialty build that requires some modifications, these should be done by a professional gunsmith. Atrius Development Group is not responsible for modifications done to your firearm or other parts as our Selectors are designed and intended to be a drop-in solution.

Yes! Due to varying tolerances the Atrius Forced Reset Selector may stick out more than traditional safeties on the left or right sides of the lower receiver.

Our compatibility list is a constantly growing document and is not the end-all-be-all answer to everything! If you have a build that is functioning consistently but features parts not already listed in our public Master Compatibility Sheet, please let us know and we will add them to help other customers’ builds in our community as well.