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Slow / failed cycling M3


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Hi all,


I'm new on here, new to M3's and new to semi autos in general. I bought a second hand M3 for PSG and sad to say it's misbehaving on its first outing.


I've tried a few different shells, 28-32 and it's the same. I had a friend watch and he says it cycling really slow and it'll eject but fail to cycle every 2nd or 3rd shot. There were a few guys there with plenty of experience on M2's in all it's variations, so some local knowledge was available, but no, it wouldn't play along.


Now, I did fit the GG&G bolt release and charging handle myself, following the instructions and the m3 manual all the way.


a second clue might be that if I switch it to pump (while empty) it gets into all sorts of problems. Bolt doesn't return forward, the pump action will lock at the rear position, it won't load correctly etc etc.


I am concerned a little that the fore end grip touches the GG&G bolt release pad when trying to pump cycle the gun.


any advice before I strip it and reassemble will be gratefully received!





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What variant is the M3? (import marks, forend selector) --- If the M3 is empty, it IS SUPPOSE to lock the forend back. The bolt is connected to the action bar IF YOU CORRECTLY locked it in and not just sitting on top the slot. You may want to check the recoil spring tension and if anything is gummed up. I don't have the GG&G pad but I have seen it on M3s.

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If the gun is new, oil it. Oil it well (action spring, bolt, bolt rails) with a non-aerosol oil like BreakfreeCLP, Militec-1, etc. A dry gun cannot operate. I agree, if the gun is empty it will lock back all the time. In the pump mode, it is designed to work as a pump. The action spring will not be strong enough to return the weight of the entire assembly back to battery, you should do this yourself as if it had no action spring. If you're putting all kinds of gear on the M3 remember, it's an inertia operated gun. Weight acts like a recoil reducer. The more weight on the gun, the slower it will operate until it ceases to operate. General rule is no more than 1 pound of extra weight over stock configuration especially if you have a PG stock.

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  • 8 years later...

Along with what was said 8 years ago, inertia guns MUST be held tight for them to function. Make sure to hold tight to shoulder. I have a couple of the HK era M3T top folding models and are flawless if held firm, but I can intentionally keep them from cycling even once properly just by the way I hold it.

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