Nuprol Defender misfiring

[Belligerent_Honky]

Afternoon all,

Asking advice for a friend on this one. 

He's recently bought a Nuprol defender second hand. Decent condition overall. 

However, it's started to misfire on semi auto. It's shooting EVERY OTHER trigger pull, but shooting 2 rounds each time.  Obviously there's a timing or feed issue there somewhere. 

Firing on full auto fixes the issue for a couple of shots.  Then starts playing up again. 

Anyone come across this and can offer advice? 

Once again, thanks in advance!

 

[Sitting Duck]

first thing - try a few different mags

some mags work better/worse in some guns

sometimes a wobbly mag may misfeed and there is tape/velcro trick in magwell

could be folded over bucking lips, causing a jam when feeding

could be overhopping causing the gun to misfeed - there is a limit to how much hop you can apply

before the bb fails to fire with backspin from nub/bucking, so back off hop a bit maybe

could be $hit bb's jamming a ttb or even a stock barrel if really $hit bb's

could be an issue inside box - worn tappet plate or something not allowing nozzle to retract 101% fully

if nozzle only clears 5.5mm in hop feed tube you ain't never feeding a 5.95mm bb

(no matter how big/long delay clip fitted)

the double firing - is box running very quick on say beefy 11.1v say 25rps ???

you will get serious overspin with too much extra juice in a stock gun & light spring

you can also get similar effects with a worn Cut Off Lever that pops late on semi

however the Nuprol I think uses a more bespoke microswitch gearbox that might have bespoke COL

(pretty sure it has a bespoke trigger & selector plate along with microswitch inside)

hopefully it is more outside the box where most of your m8's issues are taking place

hopefully trying a few different mags & decent bb's like G&G's or Blasters might help

The bucking could be folded over, just a slight crease can cause feeding headaches

and once it begins to catch it never improves like fine vintage wine

I would try a few things like above - often the daft simple stuff can be the main root of problems

 

[Belligerent_Honky]

I've got to say I wasn't expecting anything that comprehensive. Massively appreciate the time you put in.  

OK.  So it's running nuprol 7.4v 1450mah "nunchuck" batteries. The wiring to the battery connection isnt great. Connector keeps falling off. 

I won't have access to the gun until the weekend, so I'll try a few things and update wit progress. I've asked him to try reducing hop so will see how that goes first.  

It's also worth mentioning that the safe/semi/auto switch seems kinda worn? It's slips between  modes without a solid "click" about half the time. I've had to move it to auto and then back to semi just to unlock it on a few occasions.  

Cheers!