The Challenger Arms Corporation Plainsman Air Rifle (Pneumatic) (1948 to 1951)

Back in October of 2017, I came across this Challenger Arms Corporation Plainsman pneumatic air rifle in a closed bid auction. The condition was unknown, however, as I already have a few Challengers in the collection and had recently written about the rifle in the pneumatic pistol article, I thought I would have a punt. The trouble with closed auctions is that you just don’t know if someone has bid more than you. So, as the days passed and the closing date drew closer I wondered if I would be outbid. Well, as you know, I was successful!

Some weeks later I collected the rifle and took it back to Jimmie Dee HQ. Once I had unwrapped it and looked it over I tried to pump it up. Sadly, but not unexpectedly, the air leaked straight out of the exhaust port and down the barrel. It was going to need a full strip-down and reseal.

strip down and repair

Surprisingly, there were no seized or broken parts and the rifle came apart very easily. I began by removing the pump lever pivot pin, the barrel and pump chamber end cap and then the pump lever assembly. Next, I removed the walnut stock which is attached to the action with a single bolt underneath the stock. Oddly this bolt protrudes from below the stock whereas I would have expected it to be recessed and flush with the bottom of the stock. 

The barrel is held in place by a screw situated on top of the breech. This screw is used to lock the barrel in place once the barrel has been correctly positioned. The correct position of the barrel is achieved when the bolt-action pellet probe not only seals against the barrel but also locks against the action. Once the barrel support bracket was removed by sliding it off the barrel and the barrel locating screw was removed, I used the bolt-action pellet probe to push the barrel out with a few gentle taps of a small brass hammer.

Although not necessary, I then removed the bolt-action pellet probe by driving out its locking pin and then withdrawing the bolt from the rear of the action. Again, although not necessary, the trigger can be removed by tapping out the pivot pin. The pin is serrated at one end and therefore only comes out in one direction. Once you see the pin coming out of the other side, if there are no serrations, then you need to drive it out the other way. Otherwise, you risk damaging the trigger blade and the action of the rifle. If you wish to remove the rear sight it’s a simple case of removing the two screws. Be careful not to lose the elevation adjustment screw!

The pump tube simply unscrewed from the action. I used a pin punch through the pump lever pinholes to help make this easier. Certainly, when refitting the tube you will need something to help you tighten the tube down onto the valve seal. Just be careful you do not deform the tube. Certainly, there is no need to use any form of toothed grip to remove the pump tube. Doing so will damage it.

Next, I removed the hammer assembly by unscrewing the end cap and pulling it out of the action. The hammer pull rod should unscrew from the hammer weight. If it doesn’t, it may have been thread-locked in place. Heat the hammer up with a hairdryer or over a gas hob to get it hot. Then try to unscrew it. Try not to use tools such as mole-grips as the teeth will chew the pull rod and handle.

To remove the valve, first remove the valve body retaining screw from the underside of the action. Then, unscrew the internal lock nut which is accessed from the hammer end of the tube. You can make a tool for this from a hex socket with a hacksaw or grinding wheel. Once the lock nut is removed, gently tap the valve at the pump end with a wooden dowel or something soft to push it out through the rear end of the action.

fault-finding

I knew that as the air was leaking straight out of the gun through the barrel that the fault would lie inside the valve. The valve face seal would have perished and quite probably the inlet seal too. The best way to open up the valve is to push the valve stem in to push the valve body apart. Do not be tempted to use mole-grips to twist the valve apart as the grips will chew the delicate brass body with ease. Once damaged, the valve body with not be able to seal against the pump tube seal. If the body is particularly “stuck” together, you may need to use a pin punch to push the valve further in to help separate the valve body. Sometimes a gentle tap with a hammer is needed to encourage the valve body to separate.

Once I had disassembled the valve it was clear where the fault lay. The exhaust valve seal had been made from a very hard piece of plastic which was incapable of creating an airtight seal against the valve face. The inlet seal wasn’t much better either.

There was only one thing for it. It would have to be sent to Lawrie to work his magic and make some new seals. It took me a while to get it to Laurie though. I had plenty of distractions such as an airgun fair and another auction to attend! Eventually, I found the time to deliver it to Lawrie and a few weeks later he called to say it was ready.

Lawrie completely rebuilt the valve unit. He replaced the valve with one that had a captive seal and made a new inlet seal from his red polyurethane rods. He also made a new valve body to pump tube seal and a new upper to lower valve body seal. Incidentally, o-rings will also work just as well.

One feature you may have noticed is the threaded valve stem. It appears to serve no functional purpose whatsoever when fitted to the rifle. Perhaps it had some purpose during the production of the valves.

design reuse

When Daniel Fogel designed the Plainsman pneumatic range of airguns, he did so with the reuse of parts in mind. He had learned a valuable lesson from his Apache days and knew that to be successful, he had to reduce production costs. With that in mind, not only did Daniel reuse the same valve assembly in the rifle, pistol and probably the air shotgun, he also reused the entire receiver. The only major differences between the airguns are longer pump tubes, longer barrels and a rifle stock instead of a pistol grip. Having said that, I have noticed one minor difference in the receiver. Whilst the receiver is attached to the pistol grip or rifle stock at exactly the same place under the body, the threaded “pillar” used to attach to the stock or grip is much longer for the rifle than the pistol. I suspect the same moulds were used and the pillar was cut down if it was destined to become a pistol.

Keen readers of Jimmie Dee’s articles will know that the Challenger Arms Corporation eventually ran out of money and was bought by the Goodenow Manufacturing Corporation which added the CO₂ gas variant to the pistol, rifle and air shotgun lines. It is clear that Goodenow reused the same receiver and replaced the pump tube and valve with a CO₂ valve body and tube.

Unlike the Apache airguns, Daniel fitted a rifled steel barrel in either .177 or .22 calibre to the Plainsman air rifle and pistols. When the Apache was developed, it was decided that non-standard sized ammunition would be used. The intention may have been to improve the companies revenues by forcing owners of the Apache rifle and pistol to purchase Apache ammunition. Using a .177 or .22 barrel allowed the Challenger Arms Corporation to focus solely on airgun production. It also meant that there was plenty of readily available ammunition to hand and has allowed the rifle to be useful 70 years later!

There are a couple more things that I have noticed about the rifle. The stock is stamped “R9” on the joining faces of the pump handle and main stock. This probably identifies the two halves once the stock was cut in two. Marking them in this way would ensure that they would be reunited following oil treatment and during the assembly of the rifle. I also noticed that in the same place on the main half of the stock that it was stamped “R149”. Perhaps this is the rifle’s serial number.

The other feature is the rear sight. It is similar to the pneumatic Plainsman pistol except that the rifle is fitted with a peep sight. Those with good attention to detail will notice the elevation adjuster is missing from previous photographs. However, I have since had a replacement manufactured making this rifle complete once again.

capped power

In the standard U.S. configuration, these air rifles can produce a significant amount of power and it is easy to pump them over the unlicensed British 12 ft/lbs legal limit. I have painstakingly ensured that this air rifle cannot produce more power than the 12 ft/lb limit no matter how many times the rifle is pumped. The power chart below shows how much power this rifle is now producing according to the number of times it is pumped. An average was taken of five readings for each group of pumps. For example, five shots for three pumps, five shots for four pumps and so on up to thirteen pumps. Believe me, that was quite a workout!

The rifle now achieves its “capped” maximum power of 11.5 ft/lbs at ten pumps. Adding more pumps begins to reduce the power. This is because the pressure of the air inside the valve is now counteracting the force of the hammer and hammer spring. In fact, there is a limit where the hammer and hammer spring will be unable to open the valve at all. This is called valve lock.

Also, when fired, not all of the pressure is used as the hammer spring is not able to keep the valve open for long enough. Therefore it is important to dry fire the rifle once again before pumping otherwise the next shot will not be of similar power to the previous. If you forget, you will probably miss your target as the power will be quite different which would affect to point of impact. Alternatively, limiting the number of pumps can ensure that no excess pressure remains in the valve. For this particular rifle, six pumps will deliver 8.5 ft/lbs and would ensure all the pressure is released when fired.

However, I think a fair compromise of the number of pumps versus power would be eight pumps giving a respectable average of 10 ft/lbs of power. What’s more, the variance of the rifle with eight pumps is just 6 fps! Now that’s not bad at all!

range time!

Of course what really counts is how the rifle performs with targets. I packed the rifle and a tin of pellets and headed out to the range. First things first, she needed to be zeroed in and I began by zeroing her in at 6 yards. The first shot struck at 10 o’clock and was 1 inch out from the bull. I fired two more shots and was pleasantly surprised that they grouped reasonable well. I adjusted the rear sight to bring the group to the right and fired three more shots. They were close enough to the central line for me to tackle the knockdown targets and various items hanging on strings.

Shot after shot from 6 yards to 25 she hit every single target. The smile on my face was as big as a Cheshire cat’s! To give you an idea of how good it was, I thought I’d let her have a bash at a 12g CO₂ capsule that was hanging by a piece of string at 25 yards. I pumped her up to eight pumps, loaded a pellet and took aim through the peep sight. I gently squeezed the trigger and she fired. Ping! She hit the proverbial nail on the head!

Before packing up, I thought I’d see how the rifle actually grouped. I set out a board at 25 yards with some paper stapled to it. I fired one shot which I would then use as an aim point for five more shots. The first shot is the lower pellet hole on the group photo. It was very hard to see this mark with open sights from 25 yards. For this reason, I may have fluffed the second shot which is the far left pellet hole. Nonetheless, I fired four more shots which gave a group about the size of a fifty pence coin or 1 inch. That’s not bad considering I haven’t tried to find the pellet that this rifle likes and especially considering she’s 70 years old!

It has given me immense pleasure to restore this rare vintage American air rifle to shooting condition and far more pleasure discovering how well she still shoots at the range. There’s no doubt that this rifle will be making many more trips to the range!