Internal Corrosion The PCP Airgun Killer

OK, here’s a subject most of us don’t like thinking about. Internal corrosion, the PCP airgun killer, is on the rise. Here’s why and what you can do to prevent it…

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Internal Corrosion The PCP Airgun Killer – Why Is It Rising?​

Hard Air Magazine first brought attention to the danger of internal corrosion in PCPs back in 2018. And yes, the cause is still the same – it’s water vapor (moisture) in the air entering the gun when it’s filled.

Once inside the gun, the water vapor attacks metal parts and causes corrosion. That corrosion builds-up unevenly on the metal surfaces. We’ll give more details about this below. But why is the amount of corrosion in PCPs rising?

There’s basically two reasons for this…

1. When HAM first published this story in 2018, 3,000 PSI was a fill pressure used by the majority of PCP airguns. Now fill pressure is commonly much higher – 4,500 PSI, for example and trending higher. The higher the pressure, the more corrosive the water vapor.

Yes, most modern PCPs use a regulator. But it’s not uncommon for guns filling to 4,500 PSI with High Pressure Air to be set to 3,000 PSI – or thereabouts – on the regulator. Regulators have not entirely caused the problem to disappear!

Below. The Air Venturi Avenge-XL has its regulator set to 2,900 PSI in .30 caliber, combined with a 4,500 PSI fill pressure.

2. Due to these higher average fill pressures, more PCP shooters are filling their guns directly from their own electric compressor. Eight years ago, compressors were more expensive and less widely available. More shooters charged their guns using HPA tanks filled at a paintball or dive store than they do now.

Plus, you can fill a PCP to 3,000 PSI multiple times from one large 4,500 PSI HPA tank. That same HPA tank will not even completely fill one air rifle to 4,500 PSI.

So more PCP owners are filling their guns to a higher pressure – on average – using their own HPA compressor.

But many PCP owners are not using a desiccant system with their compressor. Dive and paintball store tank fills give you DRY AIR. But without a decent desiccant system – and I’m not talking of the “cigarette filter” type either – many owners are filling their shiny, new PCP air rifles with High Pressure Air that’s full of water vapor.

That’s the problem and it’s a recipe for long-term disaster…

---

Internal Corrosion The PCP Airgun Killer – What Does It Look Like?​

So, PCP airgun corrosion is caused by moisture in the air that’s used to fill an air rifle. But what does this corrosion look like and how bad really is the damage?

These HAM photographs show how bad the corrosion actually can be. Our heading photograph shows a corroded Marauder gauge port. Look and be warned!

Note that our photographs happen to show corrosion in Benjamin and Crosman airguns. That’s because these are examples we have been supplied by a Crosman Repair Center. But every PCP airgun – not just Crosman/Benjamin models – can suffer from this problem.

And – as we can see – corrosion occurs on Aluminum parts, not just as rust on steel.

You can find PCP airgun corrosion in any make of airgun!

Above. There’s plenty of corrosion on this Marauder fill adapter. You can also see oxidization build-up on the sintered filter.

Every time you fill your PCP airgun without a high quality desiccant system, you are causing this problem. You’re pumping water vapor – moisture – into the gun every time you fill it with High Pressure Air.

Over the long-term – say 3 years or more – PCP airgun corrosion will be the number one cause of failure for PCP air rifles.

First, you find that your favorite PCP is starting to loose pressure between uses. Then the pressure loss becomes more rapid. Then, finally, the gun will no longer hold pressure.

Below. Here’s corrosion on a Discovery gauge port. It’s even inside the gauge adapter (arrow). And this is on a gun operating at just 2,000 PSI maximum fill pressure…

Again – if you have been filling with “wet” air – that is air that has not been passed through a quality moisture-removal system – it’s guaranteed that your air rifle will build-up internal corrosion.

The problem will be worse if you live in a naturally-humid area. It will be worse still if you live by the ocean – think salt water corrosion now. So if you live in – say – Florida and you’re filling your PCP with no desiccant system, your PCP air rifle WILL suffer from corrosion!

Below. Here’s another corroded Marauder gauge port.

---

Internal Corrosion The PCP Airgun Killer – But What Actually Happens?​

Yes, rusting of steel HPA pressure tubes is one obvious result. If a pressure tube shows any signs of internal rusting, it should be replaced immediately!

You see, the O rings inside the gun seem to attract moisture like a magnet. The result is that rust occurs between the O ring and steel HPA tubes – usually in a circular pattern, exactly matching the location of the O ring.

Below. It’s difficult to photograph inside an HPA tube. But you can see both rust caused by the O ring and random rust in this badly-corroded Marauder tube.

I may be a coward, but the prospect of holding a rusty steel tube containing 3,000 PSI of air right next to my face every time I shoot doesn’t sound too clever. DON’T DO IT!

But surprisingly, perhaps, the majority of PCP airgun corrosion happens on Aluminum parts inside the gun, rather than in the HPA tube itself.

High pressure, moisture-bearing air causes the Aluminum to oxidize into a white substance. This white oxide then builds-up underneath the O ring seals inside the gun. But it doesn’t build up evenly!

Because the Aluminum oxide builds-up in peaks and troughs, eventually the rubber O rings inside the gun can no longer fill the gaps and leaking starts. It’s downhill all the way from there…

---

Internal Corrosion The PCP Airgun Killer – Prevention Is Better Than Cure.​

The way to prevent – or at least massively reduce – PCP airgun corrosion is to ALWAYS fill your gun with “dry air”.

If you use a hand pump, make sure it is filled with a dessicant system such as this Hill pump has.

Alternatively, if you fill HPA tanks from a compressor, use a dessicant system – such as this Diablo Air Dryer – between the compressor and the tank.

The Dry-Pac Pro Air Dryer Filter from Hill (below) delivers dry air every fill. Manufactured in the UK from corrosion resistant materials, the filter unit features four stages of internal filtration that remove moisture and particulate matter.

It’s designed to fit onto Hill compressors, of course, but the filter can be fitted to the output side of most compressors, big or small. There’s two versions: one uses common 1/8-Inch BSPP threads for the high pressure hose, it sells for $149.99 at Airguns of Arizona. The other (at $204.99) includes “Foster-type” quick disconnects.

In any case, you also need to monitor the desiccant beads and dry-out or replace them appropriately.

The Hill video gives a good overview of what is involved…

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PCP airgun corrosion WILL happen to your air rifle unless you always fill it with dry air. A desiccant filter system could be one of the best investments you ever make for your PCP airgun!

BUY FROM AIRGUNS OF ARIZONA​

Hill Dry-Pac Pro Air Dryer Filter System​

The post Internal Corrosion The PCP Airgun Killer appeared first on Hard Air Magazine.

 

[Billm]

Great article, very informative.

 

[duchunter007]

I can attest to this firsthand on a gun I bought used that came from the Southeast. I wanted to change the bottle on my gun to a larger one, so I thought I would pull out the bottle valve and put in the new, larger bottle. Well, when I finally got the valve out, the bottle had moisture in it, and the valve was a rusty mess. took the gun apart, and it all checked out good, thank goodness. I use a good filter on both of my compressors.

 

[Beanflip]

I started out only filling with the cigarette filter on my GX compressor. I used the compressor for roughly 8 hours total filling my first gun and my current gun. Now I’ve purchased and been using the GX filter and putting a couple drops of silicone oil in the hose before each fill. Are there any valuable additional maintenance procedures to remove water from the rifles? Perhaps an annual degassing accompanied by some sort of draining or drying?

 

[FL22]

When I first started filling my Taipan Veteran II tactical, I witnessed water squirting from the fill probe when I removed it. It was then that I realized I had to do something better.

My compressor is (now) on the floor with a decent size desiccant filter with color indicating beads (along with multiple cotton filters) always filling my Airguns on top of my workbench.

I have disassembled to tune and make repairs several times since and haven’t observed any issues.

Moisture damage is a preventable and unnecessary expense.

I am starting to think that used Airguns should have a basic moisture inspection included or at least available as a flat rate charge.

Such as bottle/tube removal and inspection also the regulator if visible without removal.

 

[Jaabaa]

Desiccant was used often in my field as a Lineman.
Mostly for the old Paper insulated cables..

 

[Scriv]

Here in the South East we chew our air, especially in the summer. I use an inline filter, but have always stored, and operated my compressor in air conditioned comfort. The point being that the air it consumes has had the humidity reduced already (notice that I didn't say eliminated) before it gets to the filtering system.

 

[Billm]

I fill in a climate controlled room and use the dessicant filter. I open the drain several times while filling and I’m amazed by the amount of water that blasts out. I’ve been shooting in between downpours today. At 6:30 am, it was 72f 98.8% humidity. By 10am it was 83f and 88% humidity with a sweaty heat index of 93f. I wipe the airguns down when I’m done. That’s a major difference between most PCPs and Springers: I was taught to wipe the outside of my springer barrels and cylinders with an oily cloth to protect that beautiful German bluing from moisture and finger prints. None of my PCPs have any beautiful mirror blued finishes to wipe down.

 

[Murfdurf82]

I started out only filling with the cigarette filter on my GX compressor. I used the compressor for roughly 8 hours total filling my first gun and my current gun. Now I’ve purchased and been using the GX filter and putting a couple drops of silicone oil in the hose before each fill. Are there any valuable additional maintenance procedures to remove water from the rifles? Perhaps an annual degassing accompanied by some sort of draining or drying?

I could have typed this out myself. Questions included. I thought about the 2 rifles I filled most when I had just the cigarette filter. One has been completely apart multiple times with the regulator exposed, haven't seen any damage.

Also I picked up a dehumidifier for my basement area the compressor is after I thought about humidity. Never had any issue with moisture or mold but I'm amazed how much water I'm pulling out of the area

 

[Madhatter]

A tip for those who use a fireman scba. Remove the valve and then remove that tube that sticks out of the valve into the tank. Then every once in a while turn the tank with the valve down and just slightly open the valve after leaving it upside down for around an hour. That tube is to ensure that when a fireman is wearing that tank he or she don't end up with water in their lungs as they wear the tank with the valve down. Aluminum and steel with water causes galvanic corrosion. Carbon fiber composite and any metal that's not high grade stainless or titanium will result in Electrolysis and will eat the metal. That's why there should be a layer of fiberglass between metal and carbon fiber. Think of a double a d cell or c cell battery.

 

[Danman]

I have that Hill filtration system for my compressor...worth the money and then some. That pre-filter on the hand pump though...is it good enough? Think again!!
My first 2 years of pcp where hand pump only. A/C on, replaced the dessicant twice a year, put the gun up higher than the pump....still got moisture!! Run an inline filter as well, believe me.
My Hill compressor makes quite a pool of water before i close the bleed valve before a fill, but when I changed the filter kit it was completely dry inside after 1 year of moderate use. Hill designed the water drain system very well! I have read many people running same compressor with no inline filter and have zero issues, but I wont chance it! Summers here are Humid usually.

I agree with @Beanflip .....a complete drain and quick check of the cylinder/bottle on a gun is a good idea once in a while (Anually?). Did it on my S510 when I swapped the fill port to a quick connect. Don't know if there was much moisture inside but the outside of the tank sure did get condensate on it from the de-gas.

 

[MMCM13]

I have a very quiet and accurate Gen 1 Marauder that suffers from this issue. The big disappointment is that the air cylinder has been discontinued, making the repair a problem. It annoys me that you can get so many parts for really old Crosman/Benjamin air guns, but not this air tube…

 

[Bdempsey]

OK, here’s a subject most of us don’t like thinking about. Internal corrosion, the PCP airgun killer, is on the rise. Here’s why and what you can do to prevent it…

---

Internal Corrosion The PCP Airgun Killer – Why Is It Rising?​

Hard Air Magazine first brought attention to the danger of internal corrosion in PCPs back in 2018. And yes, the cause is still the same – it’s water vapor (moisture) in the air entering the gun when it’s filled.

Once inside the gun, the water vapor attacks metal parts and causes corrosion. That corrosion builds-up unevenly on the metal surfaces. We’ll give more details about this below. But why is the amount of corrosion in PCPs rising?

There’s basically two reasons for this…

1. When HAM first published this story in 2018, 3,000 PSI was a fill pressure used by the majority of PCP airguns. Now fill pressure is commonly much higher – 4,500 PSI, for example and trending higher. The higher the pressure, the more corrosive the water vapor.

Yes, most modern PCPs use a regulator. But it’s not uncommon for guns filling to 4,500 PSI with High Pressure Air to be set to 3,000 PSI – or thereabouts – on the regulator. Regulators have not entirely caused the problem to disappear!

Below. The Air Venturi Avenge-XL has its regulator set to 2,900 PSI in .30 caliber, combined with a 4,500 PSI fill pressure.

2. Due to these higher average fill pressures, more PCP shooters are filling their guns directly from their own electric compressor. Eight years ago, compressors were more expensive and less widely available. More shooters charged their guns using HPA tanks filled at a paintball or dive store than they do now.

Plus, you can fill a PCP to 3,000 PSI multiple times from one large 4,500 PSI HPA tank. That same HPA tank will not even completely fill one air rifle to 4,500 PSI.

So more PCP owners are filling their guns to a higher pressure – on average – using their own HPA compressor.

But many PCP owners are not using a desiccant system with their compressor. Dive and paintball store tank fills give you DRY AIR. But without a decent desiccant system – and I’m not talking of the “cigarette filter” type either – many owners are filling their shiny, new PCP air rifles with High Pressure Air that’s full of water vapor.

That’s the problem and it’s a recipe for long-term disaster…

---

Internal Corrosion The PCP Airgun Killer – What Does It Look Like?​

So, PCP airgun corrosion is caused by moisture in the air that’s used to fill an air rifle. But what does this corrosion look like and how bad really is the damage?

These HAM photographs show how bad the corrosion actually can be. Our heading photograph shows a corroded Marauder gauge port. Look and be warned!

Note that our photographs happen to show corrosion in Benjamin and Crosman airguns. That’s because these are examples we have been supplied by a Crosman Repair Center. But every PCP airgun – not just Crosman/Benjamin models – can suffer from this problem.

And – as we can see – corrosion occurs on Aluminum parts, not just as rust on steel.

You can find PCP airgun corrosion in any make of airgun!

Above. There’s plenty of corrosion on this Marauder fill adapter. You can also see oxidization build-up on the sintered filter.

Every time you fill your PCP airgun without a high quality desiccant system, you are causing this problem. You’re pumping water vapor – moisture – into the gun every time you fill it with High Pressure Air.

Over the long-term – say 3 years or more – PCP airgun corrosion will be the number one cause of failure for PCP air rifles.

First, you find that your favorite PCP is starting to loose pressure between uses. Then the pressure loss becomes more rapid. Then, finally, the gun will no longer hold pressure.

Below. Here’s corrosion on a Discovery gauge port. It’s even inside the gauge adapter (arrow). And this is on a gun operating at just 2,000 PSI maximum fill pressure…

Again – if you have been filling with “wet” air – that is air that has not been passed through a quality moisture-removal system – it’s guaranteed that your air rifle will build-up internal corrosion.

The problem will be worse if you live in a naturally-humid area. It will be worse still if you live by the ocean – think salt water corrosion now. So if you live in – say – Florida and you’re filling your PCP with no desiccant system, your PCP air rifle WILL suffer from corrosion!

Below. Here’s another corroded Marauder gauge port.

---

Internal Corrosion The PCP Airgun Killer – But What Actually Happens?​

Yes, rusting of steel HPA pressure tubes is one obvious result. If a pressure tube shows any signs of internal rusting, it should be replaced immediately!

You see, the O rings inside the gun seem to attract moisture like a magnet. The result is that rust occurs between the O ring and steel HPA tubes – usually in a circular pattern, exactly matching the location of the O ring.

Below. It’s difficult to photograph inside an HPA tube. But you can see both rust caused by the O ring and random rust in this badly-corroded Marauder tube.

I may be a coward, but the prospect of holding a rusty steel tube containing 3,000 PSI of air right next to my face every time I shoot doesn’t sound too clever. DON’T DO IT!

But surprisingly, perhaps, the majority of PCP airgun corrosion happens on Aluminum parts inside the gun, rather than in the HPA tube itself.

High pressure, moisture-bearing air causes the Aluminum to oxidize into a white substance. This white oxide then builds-up underneath the O ring seals inside the gun. But it doesn’t build up evenly!

Because the Aluminum oxide builds-up in peaks and troughs, eventually the rubber O rings inside the gun can no longer fill the gaps and leaking starts. It’s downhill all the way from there…

---

Internal Corrosion The PCP Airgun Killer – Prevention Is Better Than Cure.​

The way to prevent – or at least massively reduce – PCP airgun corrosion is to ALWAYS fill your gun with “dry air”.

If you use a hand pump, make sure it is filled with a dessicant system such as this Hill pump has.

Alternatively, if you fill HPA tanks from a compressor, use a dessicant system – such as this Diablo Air Dryer – between the compressor and the tank.

The Dry-Pac Pro Air Dryer Filter from Hill (below) delivers dry air every fill. Manufactured in the UK from corrosion resistant materials, the filter unit features four stages of internal filtration that remove moisture and particulate matter.

It’s designed to fit onto Hill compressors, of course, but the filter can be fitted to the output side of most compressors, big or small. There’s two versions: one uses common 1/8-Inch BSPP threads for the high pressure hose, it sells for $149.99 at Airguns of Arizona. The other (at $204.99) includes “Foster-type” quick disconnects.

In any case, you also need to monitor the desiccant beads and dry-out or replace them appropriately.

The Hill video gives a good overview of what is involved…

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

PCP airgun corrosion WILL happen to your air rifle unless you always fill it with dry air. A desiccant filter system could be one of the best investments you ever make for your PCP airgun!

BUY FROM AIRGUNS OF ARIZONA​

Hill Dry-Pac Pro Air Dryer Filter System​

The post Internal Corrosion The PCP Airgun Killer appeared first on Hard Air Magazine.

One word solution.....NITROGEN !

 

[dunz]

One word solution.....NITROGEN !

^ this is the way

 

[FL22]

Great The Nitro Warriors have shown up, time for yet another installment of “fill-wars” where is my stale popcorn!?!?

Just kidding around, but seriously isn’t the Airgun rabbit hole deep enough $$$$ ?

Just say no to nitro .

 

[Doc Holiday]

As been said before, some drops of silicone (real silicone) in the fill port at each fill will help with that and good for the seals (preventing leaks). Also shooting the Umarex Komplete with the Nitro Cartridges (or C02 Cartridges) eliminates the moisture problems.
I too also wonder if the moisture filter on the hill hand pump does enough since it’s on the uncompressed side.

 

[NateChrony]

Aluminium (yes, correct spelling) doesnt corrode due to its protective oxide layer, unless....

There's contaminants - i.e. chloride/salts, or sulfurs, so things like Extreme Pressure oils (HPA compressors!) that have additives can cause issues.
Also galvanic corrosion - poor design where there's dissimilar metals electrically connected

A+ good & timely advice!

 

[elwoodblues]

It's not just moisture it's oxygen and Co2 that corrode your o-rings and everything else.
None of my guns or bottles get fed anything but 99.995 aka grade 4.5 nitrogen

 

[Doc Holiday]

It's not just moisture it's oxygen and Co2 that corrode your o-rings and everything else.
None of my guns or bottles get fed anything but 99.995 aka grade 4.5 nitrogen

No doubting you but does the C02 react with other items to corrode? I ask because I have some C02 guns that are pretty old and the original seals are still holding.

 

[Danman]

too also wonder if the moisture filter on the hill hand pump does enough since it’s on the uncompressed side.

Oh its true....the pre-filter alone is not sufficient; I had full on water droplets coming outta my fill whip once or twice. Hill equipment is great, but that pre-filter is simply not enough, I lived it, so did my S510 rifle .
It's supplied with a short fill hose and no inline filter for faster filling, but the risk/cost (internal pcp damage) is too great.

Biggest problem with the Hill pre-filter?
Its always open to atmospheric air, so moisture gets into the dessicant beads all day everyday, regardless of usage, the color changing beads change color real fast lol, from the top to the bottom.
Grab a cigarette style filter, chop the front portion off of the element, fill that void with dessicant, cap it from atmospheric air when not in use and fill away.