by Tom Gaylord, a.k.a. B.B. Pelletier
This report addresses:
• What is a pneumatic?
• No. 1 lubrication need.
• A short pneumatic history.
• Which oil to use?
• Other lubrication.
• Wipe down.
This report was written for blog reader Joe, who asked for it specifically; but I know that many of our newer readers also found the information useful. Today, we’ll look at pneumatic guns. There are 3 very different types of pneumatic airguns — precharged, single-stroke and multi-pump — but I think they’re similar enough to cover all of them in the same report.
What is a pneumatic?
Pneumatic airguns store compressed air for one or more shots. Single-strokes get just one shot per fill and so do most multi-pumps, though there are some that do get multiple shots. Precharged pneumatics (we shorten the name to PCP) get many shots per fill.
Big bores, which are always PCPs, get the fewest number of shots per fill, but the smallbores (.177, .20, .22 and .25) get many. How many depends on the output power of the gun and the amount of compressed air that’s available (i.e., the capacity of the air reservoir).
No. 1 lubrication need
The most important reason to lubricate a pneumatic of any kind is to seal the gun. This is similar to gas (CO2) guns; but since pneumatics use air — which is thinner than CO2, their lubrication is extremely important. The seals in the guns are all sized to their jobs. In the case of o-rings, they sit in channels that assist in their sealing role; but without the right lubrication, all would be lost.
A short pneumatic history
Pneumatics are the oldest type of airgun, and their technology has evolved over more than five centuries. The first pneumatic guns used leather seals in all places to seal the reservoir as well as sealing the firing valve.
As time advanced, airgun makers learned how to lap (polish until smooth) valve faces of animal horn that is much better and less porous than leather. These valve faces would be hand-lapped to match the exact surface of the metal (brass or bronze) valve seats to which they were fitted. When the lapping job was finished, these valves would hold air much longer than leather. Leather was still used to seal the junction around the threads of the reservoir, so the guns still leaked down — but the amount of leakage was reduced by a significant amount.
[Note: Airgun designer John Bowkett determined decades ago that precisely machined stainless steel valve faces and valve seats work best of all, providing there's enough lubrication and the machining is correct. The contact surface of this type of valve is extremely fine and narrow; but if it's perfect, this valve will be very controllable. The downside is that valves made this way are still extremely labor intensive.]
Leather seals and horn/brass valves were still being used in big bore PCP airguns up through the 1920s. Smallbore PCPs didn’t come into being until 1980, when Daystate converted one of their tranquilizer dart guns into a .22-caliber sporting rifle they called the Huntsman. Daystate was the first company to build a modern PCP; and when they did, synthetic materials were both available and far better suited for pneumatic valves. At the same time, o-rings in properly cut channels provided the remainder of the sealing solution in place of leather — and the modern PCP was born.
Synthetic seals are less porous than animal horn and last far longer. They’re not as hard as stainless steel, so the mating surfaces of the valve do not have to be machined as precisely (they have a little give to accommodate slight imperfections in the valve seats). Synthetics make the modern PCP possible. And lubrication is what keeps PCPs sealed almost forever.
Leather seals in other pneumatics
Leather has been used for the peripheral seals in multi-pump pneumatics up to as recently as the 1950s. Just like the leather seals of old, the problem has always been how to keep the leather seals lubricated so they remain soft, pliable and doing their job. Oil was used originally in these airguns in the late 1890s. But times change and today we have better lubricants. Petroleum jelly will stay on the job many times longer than straight oil, so even the leather seals in your vintage multi-pumps can be lubricated for a long time.
Which oil to use?
That brings us to the big question of the day: Which oil to use? In this instance, there isn’t just one answer. For PCPs, the right oil needs to have a very high flashpoint so it isn’t prone to explode when subjected to high pressure.
I know of two instances in which petroleum-based oil or grease has caused an explosion in a PCP. One was a vintage PCP reservoir that was pressurized to around 800 psi. The interior walls of the reservoir were coated with grease to trap any dirt particles that might get in during filling. This is a common practice with such airguns; but this time the person who greased the reservoir used petroleum grease instead of organic-based (animal) grease. The reservoir blew apart at the soldered seam! Fortunately, no one was hurt.
The other instance was one I got from a news story, and the person involved was, unfortunately, killed when his modern PCP reservoir exploded. The article said he had apparently introduced regular household oil into the reservoir.
On the other hand, I’ve safely oiled PCP tanks hundreds of times with a couple drops of Silicone Chamber Oil through the air intake port. I put several drops into the fill port before the gun is filled. When the air blows in, the oil is atomized and gets on all the sealing surfaces inside the reservoir and valves.
The oil to use in a PCP is silicone chamber oil. For single-strokes and multi-pumps, the answer is different. For either of these types of pneumatics I use Crosman Pellgunoil. Neither of these types of pneumatics are pressurized nearly as high as a PCP, and Pellgunoil always does the trick.
Can other oils be used instead of Pellgunoil? Certainly. I’ve used Gamo Air Gun Oil in my single-strokes and multi-pumps for many years. I use it exactly as I do Pellgunoil for single-strokes and multi-pumps, but I do not use it in any PCP guns.
The thing about multi-pumps and single strokes is to keep their pump cups sealed and working well. These are the flexible pump heads that force air into the guns, either one time or several. They tend to get hard over time and lose their ability to seal, but keeping them oiled and in use frequently will prolong their service lives. Not using a pneumatic airgun is what really hurts it.
For normal lubrication of moving parts, both Pellgunoil and Gamo Air Gun oil work fine. So do most gun oils, like Remoil. What you do not want to use is silicone chamber oil for this purpose because it doesn’t have enough surface tension to lubricate properly. Your parts will rub against each other and wear.
As always you can use the lubricating oils to wipe down your gun’s metal and wooden parts, but Ballistol neutralizes acidic fingerprints and lasts on the surface of metal far longer than plain oil. So, it gets my recommendation for this job. It also gets the nod for the insides of all airgun barrels.
Airgun lubrication is important, for the reasons mentioned in this 5-part report. Sealing is the biggest role lubrication performs, in all cases. We’ve looked at some very specific examples of products that should be used for the reasons stated. If you decide to substitute, you do so at your own risk.
by Tom Gaylord, a.k.a. B.B. Pelletier
The See All Open Sight is revolutionary!
This is the first test of the See All Open Sight. I chose the Crosman M4 –177 as the first rifle to be tested because the See All comes only with a Weaver base, and the M4-177 has a Picatinny rail that will accommodate it. The choice was based solely on that and little else, except the M4 had been shown to be fairly accurate at 10 meters.
For the test, I decided to fire a 10-shot group using the factory sights, which are a peep in the rear and a post up front. Since the rifle was stored in the box without its sights, they had to be mounted and sighted-in. I started with Crosman Premier Super Match wadcutter pellets but switched to 7.9-grain Crosman Premier lites after seeing the size of the Super Match group.
I was shooting from a sandbag rest at 10 meters. Five pump strokes were used for every shot in this test. The group of 10 Premier lites measured 0.84 inches, so that’s what I’ll use to compare the results from the See All sight.
Mounting the See All Open Sight
The sight went on the flattop receiver easily enough, and the 2 screws that hold it in position work well. But after I mounted the sight, I discovered that it was impossible to get my head low enough on the stock to see the reticle. All I could see was the See All name that’s beneath the triangle. The sight needed to be adjusted up.
I adjusted the sight up as far as it would go and got the reticle up to where I could just barely see it if I held my head artificially low on the stock. To sight the rifle on the target, I had to tilt my head far to the right to get my eye low enough to see the full reticle. I used a 6 o’clock hold on the bull for all my shooting with this sight, which is the only way to be precise with a sight that covers the bull.
With this sight picture, I missed the entire paper at 10 meters. So, I walked up to within 10 feet of the target and aimed again. This time the pellet struck the target backer board about 6 inches below the aim point. Something had to be done, and done quick!
I had positioned the See All sight as far forward on the receiver rail as space permitted, so now I moved it back as far as it would go, like the position of a peep sight. This made sighting easier, though I was still tilting my head way over to the right to see the reticle.
With the sight in this position, I put a Shoot-N-C bull at the top of a blank sheet of target paper and shot 4 shots at it from 10 meters. They landed about 7.5 inches low on the paper, as you can see in the photo.
This wasn’t working! And the reason it wasn’t is the straight line of the M4-style rifle. The flattop receiver doesn’t permit mounting the See All Open Sight high enough to be seen easily. It’s not the sight’s fault — it’s the rifle’s.
I was ready to call it a day when Edith suggested that I mount the sight to the Picatinny rail where the rifle’s front sight is supposed to go. It was simple enough to move the sight, so I tried it and found I could see the reticle much easier. A test shot showed that it was hitting the target way too low, however. Because the sight had been moved from the rear to the front, the adjustments had to be reversed to work.
You move a front sight in the opposite direction you want the strike of the round to go, so now I had to adjust the sight as low as it would go, to bring the point of impact up as high on the target as possible. The See All sight doesn’t have much adjustment up and down — only 45 minutes of angle. When it was down as far as it would go, the pellet was still hitting the target about 2 inches below the aim point, but that was a lot better than it had been before. So, kudos to Edith for this suggestion that kept the test running!
I shot 2 groups with the sight in this position. The first one isn’t very good, as I had half the aim point covered by the target paper, and the tip of the triangle was on the center of the bull rather than at 6 o’clock. But I still got a group that is good horizontally. It’s just spread out too much vertically.
This 10-shot group is tall, at 1.803 inches between centers, but not that wide. The aim point was an estimate of where the center of the top bull was located because the target paper covered half of it.
When I mounted the second target, I fixed the situation. The second group was shot with a 6 o’clock hold on the top bull. The aim point was much more precise in this case, and the group shows it. Although the overall group is the same 1.803 inches as the first group, 9 of the holes are in 1.125 inches. Like the first group, this one is also strung out vertically.
It seems that the See All sight isn’t made for a rifle with a straight stock line like the M4′s. The eye is too high relative to where the line of sight is. This can be seen when the factory sight is mounted next to the See All.
The straight lines of the M4 rifle are all wrong for use with the See All Open sight. With a flattop receiver, it’s impossible to get the sight mounted high enough to see without holding your head at an odd angle. So, this test was inconclusive. All it proves is that the wrong rifle was used. However, this should serve as a warning to those who might think of using the sight on their other M4-type rifles. Unless you put a high adapter under the sight to raise it up, it won’t work.
The vertical adjustment range of the See All sight is not large enough for an air rifle whose barrel is slanted downward, as so many of them are. It’ll be necessary to mount the sight on some kind of compensating base for the next test. I’ve selected a TX200 Mark II as the next test rifle, and we’ve already done a test of this rifle with a red dot sight. I have a drooper base that Leapers made when we developed the UTG drooper bases for RWS Diana rifles, and this one has no recoil shock shoulder; so, it’ll go right on the TX200 without a problem.
I’m encouraged by how easy it was to acquire the sight picture once the See All was mounted in the right position. It was much faster than a peep sight picture; and even though the overall group made with the sight is larger than the group made with the peep sight, I see that many of the pellets went to the same place. That gives me confidence that the See All Open Sight will work well when mounted on the right rifle.
I also see a bright future for this sight on pistols. The farther away from the eye the sight is, the easier it is to see the reticle. Holding it an arm’s length from the eye is no problem. I’ve already confirmed that the Leapers base fits my Beeman P1, so a test of that pistol is in the works, as well.
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, we’ll begin testing the accuracy of the Crosman MK-177 multi-pump pneumatic. Because this rifle shoots both pellets and BBs, I’ll test both, but not at the same time and not in the same way. Today’s test of lead pellets was done at 10 meters, using the iron sights provided with the rifle.
I decided to use 5 pumps per shot for the entire test. That was both easy to do and was also pretty quick. According to the velocity test we did last time, Crosman Premier lites were averaging just over 500 f.p.s. on 5 pumps.
It took five shots to sight in the rifle. The first shot was 3 inches high and 2-1/2 inches to the right. Crosman supplies a sight adjustment tool with the MK-177, and I had to use both ends of it. One end is a flat-bladed screw driver that moved the rear sight to the left. The directions are printed on the sight, so there’s no confusion.
The front sight had to be raised because the rifle was shooting too high, so I unscrewed the front sight post several turns. Shot 2 was about three-eighths of an inch too high and three-eighths of an inch too far to the right. The hole was in the black bull, but it wasn’t centered. So, I made small adjustments to both the front and rear sights and fired again. This shot cut the 9-ring, which was close enough for me. I fired the other 2 shots, and they landed near the third shot. Sight-in was finished.
Crosman Premier lites
This is a Crosman rifle, so the first pellet I chose to test was the Crosman Premier lite. The first pellet hit the 10-ring of the bull, so I stopped looking through the spotting scope and just shot the gun. After the 10th shot, I looked at the target and saw a disappointing horizontal group that measured 1.173 inches between centers. None of the shots had been called as pulls (meaning the sights were off target when the gun fired), so this group surprised me.
Air Arms Falcons
Next to be tried were the Falcons from Air Arms. They’re domed pellets made by JSB and weigh 7.33 grains. Once, again, the first shot cut the 10-ring, and I never looked after that. This time, the group was much better, measuring 0.839 inches between centers. It’s also much rounder than the Premier lite group, leading me to think the rifle likes this pellet better.
The rifle’s behavior
At this point, I’ll comment on how the rifle performs. Shooting for accuracy I found the left-mounted cocking handle to be less of a problem than it had been when I tested the velocity. My procedure was to cock the bolt, advance the magazine, close the bolt, then pump the gun. This became a routine after a few shots, and it went surprisingly fast.
I rested the rifle on a sandbag for the shooting. Though it’s very light, the rifle was dead calm on the bag. The sights did not move one bit. And the MK-177′s trigger is so light and smooth that I found it very easy to shoot this way.
Pump effort identical to the 760
A reader asked me last time how this rifle compares to the 760 Pumpmaster in pumping effort. Silly me! I should have realized that the MK-177 is a 760 in another skin, but I tested my 40th Anniversary 760 just to make sure. The pumping effort is identical; or if there’s a small difference, the 760 is slightly harder because the MK-177 pump arm is a little longer.
The next pellet I tried was the RWS Hobby. These fit the clip a little tighter, and I could feel some resistance when the bolt pushed them into the breech. Again, I checked the target after the first shot then never again until I was through. I noted that this pellet moved over to the left side of the bull with no change to the sights. There’s a lesson to remember!
Hobbys grouped very close to Falcons, with the difference being due to measuring error more than any real practical difference. Ten Hobbys went into 0.858 inche…again, the group is fairly round.
Ten RWS Hobbys made this 0.858-inch group at 10 meters. This is so close to the Falcon group that it’s too close to call. Hobbys are wadcutters which cut cleaner holes, and may have lead to their group measuring slightly larger.
H&N Match Pistol
At this point, I was ready to declare the MK-177 to be an accurate multi-pump, but I had one more pellet on the table to test. And that one was the H&N Match Pistol pellet — another wadcutter. I’ve had remarkable results with H&N Finale Match Pistol pellets in some target rifles, but the straight Match Pistol pellet has never done better than average. Until this test!
Ten pellets went into a group that measures 1.239 inches between centers. No record there! But look at the tiny group that 9 of those 10 pellets made! It measures just 0.399 inches and is very round! Ladies and gentlemen, I think we have a winner!
From the results seen here, I think the MK-177 is a very accurate air rifle. It’s worthy of a 25-yard test with an optical sight. I’m thinking the red dot sight I’m using on the TX200 Mark III would be good for that. Before I do that, though, I’ll test the rifle with BBs at 25 feet.
So far, the MK-177 is a real winner! I enjoy the ease of use and the accuracy. If I didn’t already own a 760 and an M4-177, I would, perhaps, buy this one.