ics sig 551 misfeeding misfiring and jamming

[seanycozzie24v]

Having serious problems with my sig 551. Its a v3 gearbox. I fitted a new steel tooth piston to it as the previous owner had told me it had stripped its original plastic piston. I replaced that and reshimmed the gears. Now something very weird is happening. With out a mag in it shoots fine but with the mag in it will misfeed misfire and jam. Sometimes it will unjam itself by just a few bb's rolling out of the barrel. It also makes a grinding noise when it jams or misfeeds. Also I don't think the anti reversal latch is working because after firing a burst on auto after I let my finger off the trigger the gearbox will continue to turn. Would the arl cause all these problems?? Also the piston looks worn already and I fitted a brand new one today!! All help appreciated guys!!

[wilko129]

Re: ics sig 551 misfeeding misfiring and jamming

Has the piston got fully steel teeth? If so i have been told that they have to be shimmed and AOE'd perfectly to work properly otherwise they can cause problems in gearboxes. Have you got a polycarbonate piston that you can pop in and try?

[Genista]

Re: ics sig 551 misfeeding misfiring and jamming

You should be aiming to solve why the first piston stripped before ever considering a full metal teeth piston.

The jamming sounds like an AOE issue at best. Are you sure it's ok without a mag in?
Get it open and look for wear on the piston and gears.

As for the arl, the noise of a gb un-winding is very different to over spin. So, when you stop pulling the trigger, does it sound the same as when the gb is firing or different?