M4 firing full auto only.

[Caveira]

I'm on the verge of throwing this thing out the window.

I chrono'd my d-boys M4 on Saturday, so I could get it up for sale. The fps was way down, so I stripped the box out and found that the piston o-ring had dried right out. So, I replaced it and greased everything up. Put it all back together and click. Stripped it, reassembled - click again. After about a dozen attempts, it's now firing, but only full auto. The selector plate looks all OK, so could I have done something wrong inside the box? I've stripped M4 boxes loads of times, but never had this happen before.

[Barny Hamon]

Re: M4 firing full auto only.

Is the little spring on the selector plate (outside the GB) still there? If its not you will not get semi.

[HuntR]

Re: M4 firing full auto only.

Also did you seat the AR latch properly

[Caveira]

Re: M4 firing full auto only.

Yes to both the above.

[johnnyj]

Re: M4 firing full auto only.

things it can be if it worked before :
cut off lever spring missing
contacts have been moved/pressed in by accident
spring of the trigger block is missing
trigger block not seated correct or is getting stuck

[Caveira]

Re: M4 firing full auto only.

Thanks for your help guys.

Sold it.

Mods, please close.