General Troubleshooting Flow

Start by first inspecting your lower receiver:

1. Ensure the Trigger bar is flat and uncut/ full dimension and that your Milspec lower receiver has a low shelf or Full Profile Trigger pocket. 
2. Ensure Trigger functions independently of the Selector.
3. Install Selector into lower receiver with trigger installed.
4. Apply a small amount of gun oil on the control shaft portion of the selector where the spring engages the cam-lever.
5. While holding the lever forward (to simulate the upper receiver is on), switch the selector from safe to fire to super semi to ensure concentricity and that no fitment issues are present.
6. Proceed to do step 5 again, but this time pull the trigger in each position to ensure proper function without upper on. Simulate the upper by holding lever forward, rotate from safe to fire, pull trigger and hold, fan lever rearward and then forward; trigger should have the hammer still engaged with the disconnect.
7. Release trigger to reset hammer sear.
8. Hold the lever forward (to simulate the upper being connected), and rotate to the third position (super semi).
9. Pull the trigger and once the hammer releases, push it rearward to engage the disconnect again and then fan the lever rearward and forward while holding down the trigger. 

This should reset the trigger when the lever travels rearward. The hammer and trigger should release when the lever is rotated forward. 

Install upper receiver onto lower for next steps:

1. Perform a function check with the upper receiver on, ensure the weapon is clear of any ammunition or magazines. 

With the upper on and selector in safe position, press the trigger; it should not fire. 

Switch to the second position, aka fire, and press the trigger and hold. Charge the charging handle and let it go. Release the trigger; there should be an audible click where the hammer and trigger have reset and pull the trigger again to test ensuring you do not have a dead trigger.

2. With the upper receiver on and trigger reset, switch the selector to the third position; super semi. Pull the trigger and while pulling the charging handle to the rear you should feel the trigger reset; then release the charging handle and the trigger should release the hammer when the BCG travels forward. 

Do not slowly ride the charging handle, as this will not give you proper feedback. Make sure to pull and release the charging handle quickly to simulate live fire. 

Binding Test

Before moving onto live fire, please perform the following binding test. 

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 markers 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 bind on the excess material.

Live Fire Range testing:

When testing at the range, the main issue users experience will be bolt bounce caused by the high cyclic rate of the weapon system. To see if you are experiencing this issue, check the brass of a malfunction; there should be a light primer strike. 

Light primer strikes can be caused by a few issues but 90% of these issues are caused by having a buffer weight with too little mass OR the buffer does not have the “dead blow” effect (if it is a captured buffer assembly etc). 

Upgrading the buffer weight from H1 to H2 can fix the issue as well as going from H2 to H3 (if H2 is not enough weight). Adjustable gas blocks, ammunition types, whether you're using suppress/unsuppressed platforms all can affect the bolt bounce equation.