HFC HGA194b (M9 pistol with semi/full auto) fires a couple of shots and then loses its sh*t ;)

[RostokMcSpoons]

I bought this pistol from bbguns4less about 8 months ago, so it's out of warranty with them.

It was absolutely fine for a while, but started to act oddly a couple of games ago.

Basically it'll fire up to 5 shots or so, then start acting up with clouds of gas coming out and it firing full-auto briefly before whooshing the last of the gas out.
The sort of behaviour it'd do when it was still working, after firing lots of BBs and then running low on gas.

I have two cans of Abbey Predator gas that I've used with it:
Whilst charging the mag with one of them, gas shoots out everywhere and it's a noisy, frostbite-inducing bit of drama.
With the other can of gas, nothing seems to happen and I have to wiggle it around to hear anything  at all.
To rule out either or both the cans being the problem, the site tech borrowed a can of green gas, and didn't have any different luck with that.

I've tried purging the mag.  Didn't help.

So what's wrong with it, and is it fixable? 

• Is it worth trying maintenance gas to see if an O-ring has dried out?   I can't hear the mag leaking though.
  
• Could the input valve be (technical term ahoy) buggered?   As the gun is acting like it's low on gas I am rather leaning towards this possibility.
  
• I've looked inside the slide, and the end of the air nozzle looks a little ragged, could that be the issue?
  

I hear HFC guns are hard to find spare parts for, but I'm sure I can buy a new magazine, if that's the likely failure.

I don't want to spend much money on it speculatively (I'd rather put any cash towards a TM Hi Capa) but it would be a shame to write-off a gun that cost me ... well, let's say 'too much'    , if it's salvageable

Edit:  In the spirit of adventure, I checked on YT that taking apart a mag wouldn't spring any surprises on me.  I then found my can of WD40 Silicone lube, yanked out the magazine fill valve, checked it wasn't  blocked, squirted some WD40 inside, reassembled and retried.  
It seems to have helped... a bit.  I managed to fire off 20 rounds before it de-gassed itself.  So it does look like this mag is refusing to fill properly, but basically the gun itself is working.  
Well, that's my take anyway.

So is the mag repairable or do I spend £30 on a new one?

 

[EDcase]

It does sound like its not filling properly.  How did you purge it?

Its quite normal for GBBs to vent as they use the last bit of gas when there isn't enough pressure to close the valve.

Don't use WD40 except for cleaning things as its more of a de-greasant than lubricant.

Take out the valves and soak in silicone oil.  Check O-rings and replace if you can.  (Spare generic O-ring packs are available)

Worst case, you can also try to find a replacement output valve.  I think KJW might be compatible but best to check that.

Take apart the piston and clean it up. (Its not very difficult)

Ragged nozzle indicates it hasn't been feeding well but shouldn't affect actual firing.

Check the Hop rubber hasn't been damaged.

For everyone I'd advise getting some fill valve O-rings, also known as silent fill O-rings.

They fit into the outer fill valve and prevent any leaking while filling.

You can find them in airsoft supplies but THESE are the same for a lot less money.

 

[heroshark]

Sounds like pretty much every HFC gbb pistol. Stop using it before it hits the next stage and get it shifted?

 

[RostokMcSpoons]

One thing I noticed is that I could buy a CO2 capsule mag for an extra fiver on top of the price for the gas one, and I have to think that would be an interesting experiment anyway.  And maybe make it more sellable

 

[heroshark]

Just stop using it and sell it in the warm weather. The new owner will be happy till it gets cold. Maybe they will come here for advice and I can give them the same answer, if it it hasn't got completely kaput ?. I'd also say although there are not as many aftermarket parts the newer 15mm bbu TM models are more efficient and work better in the cold.

 

[RostokMcSpoons]

Just stop using it and sell it in the warm weather. The new owner will be happy till it gets cold. Maybe they will come here for advice and I can give them the same answer, if it it hasn't got completely kaput ?. I'd also say although there are not as many aftermarket parts the newer 15mm bbu TM models are more efficient and work better in the cold.

I can't sell a gun I know is not working properly, that's just not going to let me sleep at night. 

Besides, it's not working  inside my house, and yes - the heating is on!

But I take your point.  Spend the cash elsewhere.  

 

[EDcase]

DON'T use it with Co2 ?

That will end with a catastrophic failure.

A pistol has to have a Co2 nozzle valve to function properly and a strong slide to withstand the recoil.

Pistols sold with a Co2 mag will be configured for their use.

Is THIS the magazine you need?

According to THIS, the HFC can use TM, WE, KJW and Taurus mags.  Some may be a bit tight but will cycle.

I can't sell a gun I know is not working properly, that's just not going to let me sleep at night. 

I applaud your scruples

Maybe keep it for spares.  Certain parts may be reusable with other pistols...

 

[RostokMcSpoons]

Yeah that's the right magazine, I hadn't realised there compatibility there, so I might be able to pick up a cheaper one, that's good to know!

There's an official CO2 magazine for my gun, which is why I thought it an option

https://www.kombatkit.co.uk/hfc-hg190m-airsoft-gun-magazine-hg-series-co2-c02-gas-blow-back-guns-multi-fit-4128-p.asp

 

[heroshark]

That was a joke btw, should have specified. Enjoy the paper weight for what it is and save up for something that will work. That co2 mag will die quicker than the gun did and while it does hold gas it'll kill the gun quicker.

 

[RostokMcSpoons]

That was a joke btw, should have specified. Enjoy the paper weight for what it is and save up for something that will work. That co2 mag will die quicker than the gun did and while it does hold gas it'll kill the gun quicker.

Sorry about that,  it was late, humour detector must've switched off

I won't go for that mag then.  Useful advice.   I guess I'll buy a can of maintenance gas, a diddy can of green gas that'll fit in a pouch, and maybe buy a new fill valve.  That won't break the bank, and have some usefulness with my next pistol (when I get around to buying something).  If I can get 10-15 shots out of this gun sort-of-reliably per attempt to fill it, that'll make it worth carrying as a backup and not a total paperweight

 

[Tank423]

TM and WE mags will fit and feed fine, i use a mix of TM, HFC and a WE extended mag in my 15 year old m9 and never have issues ?