Maruzen P38 GBB problems

Sounds like the previous owner has not kept it lubed up.

You're best off passing it to someone who knows a bit about GBB guns to take it apart, clean it and lube it up.

Secondly, when putting gas into the bottom of the mag, you need to do it until the valve vents the gas back outwards, this is when the magazine is full of gas. You'll notice that it goes from the hiss of the gas going in, to fine 'almost white' gas spurting back, usually makes your fingers cold when this happens. The valve stops you putting too much gas in and refuses any more. A GBB magazine (depending on it's capacity) should hold enough gas to fire out a full compliment of BBs in warm weather, I have only ever known the TM .45 to struggle for gas in the winter when a full mag of BBs is used. If in doubt, use 134A gas in summer instead of Green/Ultra gas, as they have a tendancy to break the slides of guns which cant take the power. If you think it's too strong, use a lower powered gas and try that.

Thirdly, although .25s in a pistol makes the gun more accurate, it also has a detrimental effect on your range, I would recommend using .2s in the pistol.

Hope this helps.

Also if the slide is locking back when the mag isnt empty, on the magazines there is a little nubbin at the top which is attached to the follower which pushes the bbs up in the mag, when this reaches the top it sticks out, this pushes up the slide locking bar which makes the slide stay back. May have something to do with some dirt/debris inside the gun messing with the controls.

I know my .45 gets *incredibly* dirty just after normal use, requires a complete strip down and grease after each use.

Thanks for a quick reply webby.

I'm confident that I'm putting enough gas in the magazines because the gas does stop going in after about 3 seconds and the magazine rejects any more gas, like you say.

I'll try stripping it down tonight and pay close attention to the areas you mentioned. I'd rather learn how to do this myself for the long term benefits. Teach a man to fish and all that...

If that doesnt work then Ill try some 134a in it at the weekend. Though I suspect I maybe clutching at straws thinking that it is the type of gas that is behind the problems. Hopefully not.

If that doesnt work only then will I cave in and hand it in for a service!

Take pics of where bits have come out from for re-assembly purposes, always a good idea when taking apart unfamiliar things.

The main problem is that after a few rounds the magazine sounds like it is deflating and the magazine loses all charge. I can also cause the magazine to deflate if I pull the trigger whilst on safety, albeit the gas leaks at a slower rate this way. This happens with both magazines.

Could that be knackered seals in the firing valve on the mag? i.e the cooling caused by firing making the seal shrink a bit, making it leak?

If the problem isnt rectified by stripping and cleaning this week then fortunately there is someone at POW who has a Maruzen P38. So I'll also ask them to try my mags in their gun on Sunday. Then I should be able to zero the problem to either the magazines or my gun.

There seems to be relatively little info on the Maruzen P38 on the internet. I would have thought it would have been a popular airsoft GBB pistol.

If the seals are goner in the mags then I can buy new magazines from Hong Kong.

If the seals are goner in the mags then I can buy new magazines from Hong Kong.

Or maybe new seals...

If i buy seals and the magazines still fail then Ive wasted money.

Mags for it arent THAT expensive.

you can get seals from B&Q for next to nothing

Heh... if we are talking loose change cheap then I would be stupid not to consider trying that.

I pass by a B&Q on the way home so might pop in. Do you know what the specific product is called as I dont imagine they are labelled "airsoft GBB magazine seals"!!

Thanks again.

You're looking for a mixed bag of rubber o-rings. It should be in the plumbing department.

There may well be a suitable seal for what you need, but note that some seals in airsoft mags are funny shapes.

I was once recommended soaking my seals in WD40 over night to plump them up and did that on a few mags a couple of weeks ago. It seems to have worked and I now have 3 extra working mags for my carbine. So if you don't have any WD40, pick some of that up as well!

WD40 eats rubber, so i wouldnt recommend it for seals. Parafin oil(the pharmaceutical stuff, that makes you shit!) makes rubber swell. I use a mixture of it and lanolin oil for putting grips on golf clubs, found that leaving excess on rubber grips made them swell and go lumpy, works on o-rings too i found.

Well it worked for me!

Yeah, WD40 will work for a while, but the oil content will rot away the rubber after time - so don't ever use it.
It's a similar thing I experience on a monthly basis; where some nerk has squirted WD40 into the potentiometers/'controls' of their guitar amp to stop them from being 'scratchy'. It "fixes" the fault for a month or two and then the controls either seize up or become really loose due to the potentiometer shaft damping grease being eaten away, and the resistive carbon tracks inside the potentiometers rot away!

What should be used to plump up rubber seals safely (as well as Graeme's suggestion, I'll have to try that one!) is DOT 4 car brake fluid, most brands contain a 'plumping' ingredient to help maintain car rubber brake seals - this works very well

EDIT: Just to say; If you've no DOT 4 grade brake fluid, don't be tempted to use DOT 5 - It won't work and can cause harm to natural rubber seals. DOT 3 is similar to DOT 4 but usually doesn't provide the desired 'plumping' effect.

I got some O rings from the plumbing aisle. Although Yith I do find the WD40 bath an odd one seen as the advice with AEGs, at least, is to always use silicone based lubricants.
Ill plump my rubber with brake fluid.

Update.

Ive fixed the problem I was having with this gun catching after most shots.

There is a small nub inside the magwell that the magazine feeder spring grip pushes against once it reaches the required height. It reaches this nub after the last bb is ejected from the magazine.

The way this is nub is intended to work is that when the magazine feeder spring grip pushes againt this nub in the magwell, this nub pushes the slider catch up, therby locking the slider back using the power from the blowback from the last shot fired.

The problem I had was that somehow (god knows how) the spring tensing the slider catch was on upside down and the so the slider catch wanted to catch ALL the time as the spring was pushing it upwards. I reversed the spring to its proper position and now the catch is tensed in the downward position. So now the slider will only be pushed upwards when the magazine feeder spring grip pushes against the small nub in the magwell... as its supposed to.

I know this might be meaningless to anyone who has not seen this gun in detail, but its on here for reference anyway.

Nice one, another way to test to see whether it is that, is to hold the slide slide release down as you're shooting it.

Exactly Webby.
Before the fix I had to thumb the slider catch down after every shot.

What should be used to plump up rubber seals safely (as well as Graeme's suggestion, I'll have to try that one!) is DOT 4 car brake fluid, most brands contain a 'plumping' ingredient to help maintain car rubber brake seals - this works very well

EDIT: Just to say; If you've no DOT 4 grade brake fluid, don't be tempted to use DOT 5 - It won't work and can cause harm to natural rubber seals. DOT 3 is similar to DOT 4 but usually doesn't provide the desired 'plumping' effect.

I was about to say the same thing, good thing i read down, i used dot 4 on the seals of my broomhandle, it works a treat

NEVER USE WD 40 or any solvent based liquid, it WIll rot the rubber, just a question of time
(every aeg manual tells you to use only silicone based lube for this reason)