Ver. 2 switch assembly and selector plate.
 

i recently installed a new switch assembly and selector plate into my m4.

problem: the gun will only fire fully auto.

So safe=safe, auto=auto and semi=auto?

10-4

Is your cut off lever still in there and not broken? Lol.

well, its in there, i think i may have installed somthing backwards, or in the wrong position.

Your dog leg (cut off lever) may be not properly shimed (ie. it's binding with the selector gear and therefore not kicking out the trigger contact when cycling on semi). Check by sliding the selector plate through the three positions, and see if the spring is kicking the dog leg forward when selecting from full auto to semi.
-OR-
You may have bent the two copper tines (that stick out the side of the mech box under the selector plate) and they may be making continous contact. Try gently bending them back in.

Check both, and good luck.
SHA DO

Have you remembered to put the little spring back on the selector plate after you replaced switch block an selector plate?

I'm guessing that it's a high probability that the cutoff lever is getting stuck and not doing it's thing properly. Definitely check:
1. Cut off lever spring is in place
2. Cut off lever movement...should move nice and free by moving the selector plate back and forth by hand (no...I don't mean jerk it off :D )
3. Switch contacts aren't messed up
4. That it works before putting it into the lower receiver

If you have to open the mechbox, check:
1. That the cut off lever screw is not too tight (did that once), causing it to not travel far enough
2. That the foot on the cut off is actually engaging the switch block and flicking it up...you'll have to kind of hold things in place with both hands to do this.
3. That the -ve wiring is actually not reversed, where the battery is connected to the wrong contact point (done that twice..d'oh...but it makes your rifle fire nonstop as soon as you plug the battery in).
4. You haven't split the sheilding anywhere and created a short (happened in the 2nd last repair...it would fire FA with a slow/gradual semi trigger pull...neat..kind of like a reverse AUG trigger)...but it had a MOSFET in it, so don't know if that would happen without a MOSFET
5. That the shim under the sector gear isn't too large in diameter and is interfering with the oval-nub thing (on the gear's underside) and the cut off lever.

If all else fails...strip everything out...start over...cross fingers...

Can't think of anything else, best of luck!

of course

Check your selector plate spring if it is still there. If you loose that small spring your gun will go full auto and other reason is broken contact switch(the one that is pushed by your trigger pull).

Also try to not fully tighten your grip screws tighten them then turn 1/2 turn off, cause mine kept firing full auto in semi because the selector plate would jam and only go between the fullauto/safe positions, i could get semi auto but having the selector switch about 1/8 the distance from safe to semi

I've found this problem a couple times, generally it was from not putting the lower grip on properly, gotta work the selector switch into the plate by moving it to semi, then put the grip on fully. Worked a couple of the occasions, other times there were other issues like the cut off lever being too loose, worn out, etc.

I gotta remember that one. Armorlites are easy-cheesey to work on, but they occasionally suffer from the weirdest problems.

SHA DO