M4 Only fires Full Auto,

[Exarach]

I have recently been disassembling and completing work on my M4, and had a rather interesting problem, when I resembled the gun, with nothing new but a good shimjob, it wont fire on semi auto, the gun will only fire fully automatic.

-Perplexed I removed, inspected, and replaced the selector plate, still nothing, I am at a loss as to what is going on,

Anyone have any good ideas? The internet has given me very few viable solutions so far in my searching, so I figured I would throw it out there and ask a group with a live reaction.

Is there anything in the trigger mechanism that could cause this?

Thanks in advance.

[airsoftguy01]

Cut off lever, cut off lever spring?

[Exarach]

its possible, however, it looks ok. Not too tight either, and the contacts on the mechanism look good as well

[Sk8rSeth]

talk to C_Ham about it, he did the same thing and we figured it out, basically there was something that was making a constant connection with the trigger switch

[yammie r6s]

i have had the same thing in the past and upon inspection opened up the gun and everything looked fine, drove me apeshit but after lengthy hours i swapped out the cam worn cut off lever and it worked. if you have spare parts compare the two cam contact points on the end of the lever.

either that or your spring that controls the lever is gone..

[rockettravis]

If you checked everything and its good than here is the problem......
I think your sector gear is shimmed to high, If its too high the cut off cam can't engage the lever fully.