TM MP5 Tappet not cycling correctly

[Robbo DOA]

Been tinkering with my old MP5 recently but I'm having issues with it.

If I watch through the hop up I can see the air nozzle doesn't cycle back and forth fully on every shot (the gun shoot like 1 bb in ten) I've had it in bits loads of times I know the nozzel is in the tappet plat correctly and that the tappet spring is in place. I think the shimming on the selector gear is correct.

Any of you guys come up against this or got any ideas

cheers

Robbo

[Ells]

Re: TM MP5 Tappet not cycling correctly

try a sector chip or new nozzle, though its hard to say without seeing it, or knowing whats inside your mechbox

[richardy]

Re: TM MP5 Tappet not cycling correctly

i had an issue with an ics mp5 once which was a binding tappet plate, ie the tappet plate was to wide for the gb shell, you have to remember that theres always a chance for incompatibilitys in airsoft. You can remove all contents from the gb shell and just install the nozzle and tappet plate, tighten the shell and see how it moves... other times ive seen sector gears shimmed so high they also push on the tappet plate and when the gb shell is tightened the tappet plate / gears barely move. I try to word help as what i have seen, as opposed to what yours might be specifically, as with all tech problems you will have to go inside and take a look. just some ideas.

Theoretically a gun should be working fine before a sector chip is installed, its simply there to increase the feeding window time on high speed setups. So if its not working on singles and normal setups id look elsewhere.

That said it could be working fine and you just think its not moving.. a good test for mags is to turn the gun up side down and shoot on singles if it now feeds theres a potential mag feeing issue / hop issue.

[Robbo DOA]

Re: TM MP5 Tappet not cycling correctly

Thanks for the replies guys. As far as I'm aware its all standard TM parts in the box. The tappet moves fine when its installed (moved by hand)

I'll have another look at the cycling tonight and see if that throws anything else up.

[Robbo DOA]

Re: TM MP5 Tappet not cycling correctly

Thanks for the replies guys. As far as I'm aware its all standard TM parts in the box. The tappet moves fine when its installed (moved by hand)

I'll have another look at the cycling tonight and see if that throws anything else up.

Ok so I tested feeding the bb's one by one with the gun upside down and still its not feeding correctly. I took the GB apart removed the tappet spring and stepped the gears round it all seemed to track correctly, reattached the spring and (making sure everything was correctly positioned) I closed up the GB without the piston. I Positioned the GB correctly in the gun with the air nozzle in the hop up unit, again with the gun upside down and the feed tube loaded with bb's I started winding the gears round manually. The tappet seemed to cycle correctly loading a bb into the hop unit and pushing it down the barrel. I put the piston back in and tried to test fire (with the motor attached) but again it only fed one in ten or so shots! arhhhhhhhhhhhhhh

[richardy]

Re: TM MP5 Tappet not cycling correctly

well.. lets get into history.. is it a completely stock tm gun? when did it start doing this?

It only takes a mm off and suddenly its not feeding. I would go down the route of either A: shorting the nozzle 1mm at a time, chroning before and after each time. B: new tappet plate and nozzle if you dont want to phaff about.

turning upside down and shooting rules out mag, so it has to be the tappet plate not pulling the nozzle back enough, now if you say hop units in the correct possition and the the tappet plate and nozzle operate correctly then it has to be that its not pulling it back enough. Like has been said you could get a sector chip, its not a bad idea regardless but its a bandade on an underlying issue. maybe the tappet plates worn so its not pulled back as much as it previously could. maybe a bushings worn and the gears offset and not pulling it back enough.. maybe hop rubber bunched up or something stopping feeding.. spit balling here of course..

either way youve done your tests, nozzle not coming back is the cause, just gotta try either a or b for a resolution. Of course if you replace it then you need to look into reassembly and hop and or gearbox being out of position for somereason. as long as they stay lke that its still fixed with the nozzle mod.