Airsoft Canada - View Single Post - G&G UMP Feeding Problem ( shoots 2 bb at the time )

mcguyver · August 15th, 2006, 20:17

It could be due to poor engagement between the tappet and the sector gear.

Apparently, G&G had issues with their first tappet and released a "new and improved" one last fall. I worked on one last Sept. and the fellow got about 1/2 of a mag out of it before it failed. As it turned out, the tappet wasn't broken as initially suspected (the nozzle didn't move during the firing cylce) but rather the sector gear was shimmed so that it bypassed the tappet entirely. It did engage enough of the tappet to work for about 40 rounds before it wore a groove in the tappet and then failed to engage it.

All I had to do was to re-shim the gears for a proper sector gear/tappet engagement and it's been running ever since from what I hear. I did have to re-use the tappet as no replacements were available at that time, but so far so good.

But this did require a complete teardown of the gun and mechbox.

And while you're in there, remove the lithium grease from the cylinder. It'll save you from the other G&G problem of too much resistance to piston movement and the resulting stripped piston.

August 15th, 2006, 20:17	#2
mcguyver Trader rating Join Date: Aug 2005 Location: Northern Alberta	It could be due to poor engagement between the tappet and the sector gear. Apparently, G&G had issues with their first tappet and released a "new and improved" one last fall. I worked on one last Sept. and the fellow got about 1/2 of a mag out of it before it failed. As it turned out, the tappet wasn't broken as initially suspected (the nozzle didn't move during the firing cylce) but rather the sector gear was shimmed so that it bypassed the tappet entirely. It did engage enough of the tappet to work for about 40 rounds before it wore a groove in the tappet and then failed to engage it. All I had to do was to re-shim the gears for a proper sector gear/tappet engagement and it's been running ever since from what I hear. I did have to re-use the tappet as no replacements were available at that time, but so far so good. But this did require a complete teardown of the gun and mechbox. And while you're in there, remove the lithium grease from the cylinder. It'll save you from the other G&G problem of too much resistance to piston movement and the resulting stripped piston. __________________ Age verifier Northern Alberta Democracy is two wolves and a sheep discussing what's for dinner. Freedom is the wolves limping away while the sheep reloads. Never confuse freedom with democracy.