Home :: What are PCP Air Rifles?

What are PCP Air Rifles?

What are they and how do they work?

PCP's (Pre-Charged Pneumatics) - How do they work?
PCP guns use compressed breathable air as the propellant to fire pellets. For this purpose the air in the gun's air tank is compressed to 2700-3000 psi (pounds per square inch) by using a high pressure hand pump, scuba tank or carbon fiber tank. Once the gun's tank is filled to the desired pressure level, the gun is ready for use. The firing sequence of a PCP is really quite simple. When the trigger is pulled a valve opens and a quick burst of compressed air is released to travel up the barrel pushing the pellet in front of it. Each time the gun is fired the pressure and volume of available air in the gun's air tank is slightly reduced.

How many shots can you get before recharging is necessary?
Eventually the gun's air tank will not have enough air pressure or volume left to propel a pellet at the velocity needed to maintain a predictable trajectory. At that point, the pellets path degrades and alters the point of impact by as much as a quarter inch or more. Subsequent shots will not be "predictable" for shooting with pinpoint accuracy so the gun should be recharged.

We refer to all those shots with a nice, flat, predictable trajectory as "usable shots". Simply put, once the trajectory degrades due to lack of air pressure/volume, they are no longer "usable" in any predictable sense. The number of usable shots a shooter can take before reaching the recharging point varies due to a number of factors such as the gun's power, original charge level and the distance one is shooting. Does all that sound rather complex? Well it actually is much easier to work with than it sounds, so don't let these factors scare you off.

Remember the simple, less confusing days of PCP ownership?
For readers who are new to the PCP airgun market, let me assure you that getting started in the PCP world wasn't always as confusing as it is today. Mostly because there were only a few PCP models available to purchase. Beeman offered the Super 12 and Mako, BSA offered the Super10 and RWS had the 75to1 and the CA-100. Those were about the only guns available to the mass US market. There was no high pressure compressor to use for charging the guns and no hand pump either. Those items wouldn't arrive until the Career 707 showed up on the scene a number of years ago.

All the guns were charged using scuba tanks and each gun required it's own scuba charging adapter (purchased separately) that was designed for use with only that one model. But it did make purchasing a PCP less confusing. When a person decided to purchase a PCP, they simply purchased the specific scuba adapter for that gun model. If a person decided to purchase a second or third PCP rifle, they bought additional scuba charging adapters dedicated to a specific gun.

Although that was a simple concept , it was also rather expensive to purchase two or three scuba charging adapters. Why did this happen? Because some guns had a detachable bottle and their scuba adapter was designed to have the bottle screw directly into the adapter. Others were designed for use with "probes" with specific thread sizes. See following paragraphs below for details on charging types and parts. Well, we still carry all of those separate, specific scuba adapters and they are wonderful purchases for a person who only wants to buy one PCP rifle or pistol. No adapters needed, no special parts...just buy the gun and adapter that is made to charge it. Feel free to ask us about those specific scuba adapters pictured on the site if your goal is to keep it as easy and simple as possible.

But today there are new charging options available to the purchaser as well as many new PCP rifle and pistol models as well. And if you ever intend to own more than one PCP rifle, there are now additional options available to charge all those guns quickly and easily. In the following paragraphs we will explain the different charging methods needed for different PCP rifles, the individual parts needed to charge these rifles and the new quick connect adapters available for owners of multiple PCP rifles. But for those that only want one good PCP rifle, don't forget that a scuba adapter designed just for a specific gun can still be ordered in most cases.

Filling Methods for Pre-Charged Airgun
In the previous section we talked about the simpler, earlier days of using only a scuba tank and specific charging adapter for each rifle. But nowadays, a buyer can choose from a number of new charging tools. There are multiple hand pumps available on the market today from Hill, Benjamin Sheridan and Air Force. They all use the same thread patterns so all can be used for PCP charging. All three brands are very universal because they have a hose to which any number of adapters can be attached as needed for different gun models. The Hill also features a moisture filter called a Dry Pac which the other brands do not have. 

Before your airgun will function it needs to be filled with compressed air (not CO2) as stated above. There are three basic tools that can be used to fill your PCP airgun:
1. A handpump, which works much like a bicycle pump except for the high pressure.
2. A scuba tank or Carbon Fiber Tank. Scuba tanks are standard 80 cu. ft. diver's tanks. All scuba charging adapters are made to fit the dinn on a 80 cu. ft. tank. Carbon Fiber tanks are 88 cu. ft. in volume and are charged to 4500 psi which is a lot higher pressure than scuba tanks.

There is no right or wrong tool to perform the charging function. Each of these methods has its pros and cons. A hand pump requires multiple strokes to add air and although they pump quite easily, the process can be a bit tiring. On the other hand it is a portable tool which can quickly renew your air supply wherever you happen to be when you wish to shoot. Scuba tanks require periodic refilling at a dive shop and are heavy to carry. But on the plus side, they make refilling quick and easy with little physical effort. The carbon fiber tank is fairly light (15 lbs. when filled) and more expensive but it yields many PCP fills.

What items/parts are required to fill an individual PCP?
Determining which parts are needed to charge an individual PCP will depend largely on the gun one chooses, so some explanation is required at this point. It's quite easy to understand if you think of it in the following way. There are only three elements in the charging process. The air source (hand pump, scuba tank or Carbon Fiber Tank)), the gun's air tank (fixed to the gun or detachable) and the parts in-between which are the link between the air source and the gun's air tank. The confusing part for a buyer has been trying to figure out which part or parts are needed to link the air source to the gun's air tank. Hopefully this section will make that task a lot easier.

The main reason for the confusion in determining which parts are needed to connect the air source to the gun's air tank has been that there aren't many common standards. Not only are there multiple ways of linking the air sources to the gun's air tanks but there are multiple thread types as well. Let's take a closer look at some of these linkage types.

1. Probes - these are threaded units that simply attach to the air source's hose (hand pump, scuba charging adapter or carbon fiber tank) and then are pushed into the gun's charging port when recharging is needed. Examples of guns that use probes for charging are the Eun Jin Sumatra  and Weihrauch HW100 air rifles. Probes are always provided with the gun in the purchase price.

2. Collars - these are units that look and work just like the ones we use to fill our car's tires. They have collars which pull back and then attach to the male charging unit on the gun's air tank and lock in place when the collar is released. Guns that use a collar for recharging are the Benjamin Sheridan Marauders and Discovery's.  Collars units are provided with the gun in the purchase price.

3. Twist Caps or Collars- this is a unit that is similar to the collar charging unit except for one variation. The twist cap is screwed onto the air source's hose and then is pushed onto the male unit on the gun's tank and given a small 1/8 turn twist to lock it in place. Air Arms S500'sand S510's utilize this type of system and it's quick and easy to use.
is threaded, while the air source's hose has a female coupling which screws directly onto the male unit on the air source. The gun that uses the screw-on method is the

4. Adapters for Detachable Bottles - These are adapters that are needed to accommodate gun's which utilize detachable air bottle/tanks. The larger sized thread pattern of most  detachable bottles do not fit the smaller thread pattern on the standard air source's hose so an adapter is needed to allow the gun bottle to be mated to the air source hose. Gun's with detachable bottles that will need an adapter are the Theoben Rapids and Air Force Talons or Condors. The adapter is not provided in the purchase price and needs to be purchased separately. However, Theoben now offers a quick-fill option to eliminate the need to remove the bottle from the gun for charging.

What if I own multiple PCP's? Quick-Fill adapters to the rescue.
The previous section was an introduction to the various types of charging parts needed for individual guns. However, anyone that owns more than one PCP knows how irritating it can be to have to use a linkage probe for one gun, a collar for another gun and an adapter for yet a third gun. Well, all three ends won't fit on the air sources' hose at the same time, so that's where the Quick Connect parts come into play.

To simplify the whole process, we would suggest setting up the Quick Connect System. The Quick Connect System has a Quick Connect Kit for all your guns. The Quick Connect Kit provides a Female fitting which screws onto your air source hose, a special adapter if necessary and a Foster Male fitting which attaches to the special adapter or the gun's charging probe. The Male fitting unit easily snaps into the Female Quick Connect unit by simply pulling the collar back, inserting the Male fitting and releasing the collar on the Female to lock it into place.

Once the Female fitting is installed on the hose, adding new guns is simple. Simply purchase a Male fitting for the new rifle. Some rifles will require a special adapter so be sure to ask when ordering. The  Male attaches directly to the probe that comes with the gun or to the special adapter if one is needed. The male then plugs into the female on the air source hose.

The Quick Connect System requires only a scuba adapter, hand pump or carbon fiber tank with a hose. Hill and Benjamin Sheridan handpumps, scuba adapters and carbon fiber tanks have hoses that will work well with the Quick Connect System. 

Hopefully this information will help new shooters understand that owning and charging a PCP pistol or rifle need not be complicated or frustrating. But it does require the proper connecting pieces to make your shooting experience a pleasant one.

Other Items for PCP use
There are a couple of other items which can help you maximize the performance of your PCP. One of these items is Napier Pellet lube which is a pellet lubricant.  Lubrication slows down lead build-up in the gun's barrel and provides some protection against rust in the bore. Special synthetic Silicon Grease is another product that extends the life of breech seals, O-Rings of all kinds and magazine seals (multiple shot guns) and is easy to use. Simply rub a little silicone grease on those parts after using to keep them supple and pliable.