Ok feel abit of a tit now all bk together firing great but everything is full auto lol what have I done wrong I'm guessing it a simple fix
Normally that will be selector plate & Cut Off Lever or COL related....
The selector plate should not be the case if all working OK perviously in same gun
sometimes when replacing the plate or different receiver a bit of modding might be needed
BUT I'm going to assume the selector plate operated perfectly in semi previously - so plate is ok
(had one crack on refitting into M4 receiver but I think it would struggle on full auto - nah doubt that too)
is the small spring - selector plate & COL present & fitted correctly, this returns the COL on semi
in auto the COL is pushed upwards and stays upwards disengaging the COL's action
in semi COL pops the trigger switch trolley off the trigger - the sear and flies back to reset
It needs that tiny spring to ensure the COL returns asap blah blah blah
I think most likely the COL spring is missing or not working correctly
or somehow the COL is not returning properly
sometimes if COL is tightly fitted inside the box it can bind or slow return
normally it operates a tiny bit loosely than too tightly if you understand - especially if COL gets changed or refitted
The COL itself could be worn - but if it was working beforehand on semi then I tend to doubt this is the case
COL's all look ok until you compare a brand new one and then you see the wear but I doubt if COL
is that worn tbh more likely the issue is not wear but operation or fitting issue is my gut feeling
If still no easy fix or joy then most likely it is going to need to be stripped down - bummer
At the point you have gears assembled and no cylinder/piston but you are doing a "spin test" for shimming etc...
This is the point you have trigger, switch, selector plate etc also fitted...
When conducting the gears "spin test", engage semi with selector in center and pull trigger on semi....
now roll the sector backwards through cylinder window whilst trigger pulled in semi...
as the sector's teeth finally disappear then the COL should soon rise, pop the trolley and reset the trolley....
If it doesn't operate correctly something like trolley/trigger/COL is not operating correctly & needs further investigation
Hopefully some pointers - but tbh re-reading some of you original post it is unclear if this box previously worked correctly
Also sometimes fitting or rebuilding a box from scratch throws up some other issues
or
fitting another gearbox or other make into another gun can throw up a few glitches - nothing major usually
but not everything is all 101% TM compatible no matter what they say
So it could be a qwirky issue with selector plate or fire select operation too
a little more info/history of gun/project might help but sounds like a simple mechanical COL issue at first guess
hope some of this helps - did my best from description or pointers to check
