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Unintended Firing

1744 Views 19 Replies 6 Participants Last post by  OutlawAirsoft
Hey all,
I am installing a very simple 3034 mosfet in an ar47 I recently purchased and am having an interesting issue. The 'fet works fine, but with everything put together, when I switch from semi auto to full auto it starts cycling. It only cycles about a quarter of the way, but it is anoying and sometimes that causes it to fire. I have looked inside the gearbox but don't see anything obviously wrong. I suspect the cutoff lever is bumping the trigger trolley enough to complete the circuit, but I can't tell for sure. It also occasionally fires full auto in semi auto mode.
Any advice would be greatly appreciated.
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I think you have the right idea. It could be difficult to isolate the issue since the sector gear can affect the position of the cutoff. If you re-shimmed, try shimming the gears a bit higher or maybe try a stronger spring on the trolley. When I was first starting out, I was having issues shimming too low in standard mechanical switch systems, causing the sector to rub on the cutoff lever and not allow full range of motion. It would commonly block the trigger trolley completely or otherwise make a clicking noise if it was able to slip by OR just not allow the COL to engage the trolley at all and just shoot full auto in semi. At the time, I was having trouble getting good shimming on the gun (VFC avalon), so I opted for modding the trolley by sanding more of a slope on the surface that was meeting the cutoff lever so it could slide by. After this mod, it worked flawlessly, but this did not prove fruitful for me in another attempt, in which I opted to re-shim higher (Specna Arms Edge M4).
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