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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…
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.
