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Education / Training Methods of power adjustment — springers: Part 1

Methods of power adjustment — springers: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • More power!
  • Example
  • Stronger mainspring?
  • Piston stroke
  • Increase the piston length
  • Dual power is possible through piston stroke
  • Larger piston?
  • Cost
  • Transfer port size
  • Port location
  • Piston weight
  • What can be done with this knowledge?

Today’s topic was suggested last week by reader Riki from India. A lot of other readers jumped on the bandwagon when he asked for it, so I agreed to write a series of reports. The question is — how do airgun manufacturers control the power/velocity output of the guns they make?

More power!

An American airgunner who is new to the hobby will look at this in a different way. He will wonder how airgun manufacturers get the highest possible velocity/most power from an airgun. He won’t appreciate that in nearly every country in the world other than the United States the governments have limited the power of airguns. And there is no common way they limit it. In the United Kingdom they limit the output by energy, allowing no more than 12 foot-pounds for air rifles and 6 foot-pounds for air pistols, I believe. They aren’t concerned with velocity, except as it produces energy. This is a thoughtful regulation that forces airgunners in those countries to learn basic ballistics. It also forces manufacturers to test their airguns with almost every pellet to be sure they are not exceeding those limits.

Spain and Germany also limit airguns by energy, though they vary widely. Spain allows around 17 foot-pounds, I believe, while Germany is just over 5 foot-pounds.

Other countries like Denmark and Canada limit airgun velocity rather than energy. That’s a more simplistic way of doing it and it does allow the larger calibers to slip past with energies sufficient to kill deer and similar game. But the point is, no matter what country you are in, with very few exceptions (New Zealand?), airgun power is limited.

Where this comes into play is when a manufacturer wishes to sell their airguns in different markets. They must learn what those markets permit and not only produce guns that meet the specifications, they also have to ensure that their guns cannot be easily converted into an illegal configuration for that country.


Let’s say Crosman makes a breakbarrel rifle that’s very popular in the United States. It’s accurate, easy to cock and has a great trigger, plus the price is just under $300. It gets 1,100 f.p.s. in .177 caliber with a 7-grain lead pellet. The U.S. market will be good for around 10.000 sales over the next three years. That’s good, but if you could sell this rifle in the UK, the sales potential would almost double. Canada, Germany and the rest of Europe are pretty much out of reach for this gun without a major redesign. But is it worth it to try to reduce the rifle’s power from 1,100 f.p.s./18.8 foot-pounds with a 7-grain pellet to 12 foot pounds/879 f.p.s., for the UK market? A bunch of airgunners sitting around and having a bull session will probably say yes, but do they know what that involves? That is what today’s report is all about.

How do airgun manufacturers control the power output of the airguns they make? Today we will look at spring-piston powerplants.

Stronger mainspring?

The novice response to gain more power is to install a stronger mainspring, and of course the reverse would also be true. But it often doesn’t work as you might think. Not only does a more powerful spring usually not increase the power/velocity, it almost always decreases it, while increasing the effort to cock. A strong mainspring has a place in spring gun power, but it is one of the last things to consider. Several things are far more important.

Piston stroke

One of the easiest ways of controlling spring piston air rifle power, all other things being equal, is by changing the length of the piston stroke. Hot-rodders knew this way back in the 1940s, but airgun designers didn’t catch on until the late 1990s. Now they all know about it. The longer the piston stroke the greater volume of air that gets compressed and the more power it produces. But there are several ways to do this and not all of them work well.

Increase the piston length

I have read where people advise others to just put a piston extender between the piston and the seal to reduce the length of the stroke and decrease power. This can work (though some alteration of the cocking slot may be required) but it can also be easily overcome by removing the extension, and customs inspectors are wise to it. They may not catch a single gun coming into the country, but they will certainly stop an entire shipment of airguns that have this feature. You see, customs inspectors are used to being fooled, tricked and hoodwinked. There isn’t much they haven’t seen. No reputable company would ever try to pull the wool over their eyes, because Customs has the power to seize entire shipments and fine shippers for violations.

The better (read more acceptable) way of limiting piston stroke is to redesign the piston and cocking linkage so the stroke is permanently reduced. Diana inadvertently did this in the 1970s with their Diana model 35. It’s a large breakbarrel rifle that looks like it ought to be a powerhouse, but the short piston stroke limits its capability, with no easy fix. When the model 34 came out a decade later, it was vastly more powerful — just from having a longer piston stroke.

Dual power is possible through piston stroke

Since the piston stroke does control the power, it is possible, through design, to control and vary the power on a gun that way. The Beeman P1 pistol is such a gun. In .177 and .20 calibers the P1 has two power levels. They are selected when you cock the gun. Stop at the first place where the piston is caught by the sear and you have low power. Continue to cock the pistol to the second and final detent and the power will be greater. This is a dramatic demonstration of how piston stroke affects power.

Larger piston?

Okay, BB, I get it. Longer stroke means higher power. But, what about a bigger bore?That’s also what hot-rodders do — they increase the bore size of their pistons.

Yes, but hot-rodders don’t have to fit the engine block to their shoulders. A bigger bore does increase power just like a longer stroke, but when you get over a certain size, the spring tube becomes unmanageable. Stroke length is the best way to increase power and piston diameter is second best.


Before we move on I just want to say that, while stroke length is a great way to control the power of a spring gun, there is a cost involved when you want to make a change. The individual airgunner thinks it’s just the cost of the parts, and as far as he is concerned, that’s all it is. But the manufacturer that wants to produce those parts has to look at the additional engineering that’s required to make the changes.

The piston and cocking linkage will have to be changed at a minimum, but usually changing those parts necessitates a new mainspring, as well. Instead of $90 for just the new parts for each airgun (yes, the other parts do come out, so the cost of the gun remains the same), think about $35,000 to design the changes, prototype the parts, test the prototypes, make additional changes, test those, baseline the software for the new parts, including cataloging the parts and their new numbers to keep the inventory straight, making catalog, advertising and online changes that differentiate the new guns of different power but the same model name (remember the 4 power levels of the Diana Mauser K98?) and any legal fees involved in getting the new guns accepted by the state departments/home offices (and their customs departments) of the various nations to which you wish to export. Did I say $35,000? Perhaps even more!

Are there other ways of controlling spring gun power? You bet!

Transfer port size

There are two ways to LOWER the power of a spring-piston airgun using the air transfer port. First, make the air transfer port smaller and second, make it larger. It turns out that the air transfer port is usually optimized for a particular model of airgun, although caliber changes in a specific model does blur this optimization a small amount. What I mean is — a certain springer in .177 may need a port of a certain diameter, while in .22 caliber in the same gun a slightly larger diameter port might work slightly better. The differences I’m talking about are extremely small, thousandths of an inch, which is why when companies make a certain model. the transfer port is the same size regardless of caliber. Nobody can afford to make three different spring tubes for one model airgun just to optimize the transfer port size.

When I wrote The Airgun Letter and also the Beeman R1 book, I did some testing that demonstrated that a port size of around 0.125-inches or 3.175 mm seems to be a good size for many guns. If you want to read more about this I extracted the chapter of the R1 book that deals with transfer ports and put it into a report.

I once saw a production port as large as 0.150-inches which is 3.81 mm, but that was on a mega-magnum gun that had a huge piston. I’ve also seen ports that were smaller than 0.125-inches, but not by much. However, port size isn’t the only thing.

Port location

Where the transfer port is located in the airgun also makes a difference, when it comes to power. A port in the center of the compression chamber that flows straight to the breech is the most efficient and will give the highest power. A port that is located in the center of the compression chamber and then angled to the breech, or a port located on the edge of the compression chamber end and angled to the breech is less effective. However, these port location choices are never made to control power. They are fundamental design choices for the entire airgun. But when a company like Air Arms puts a central port in the chamber of a rifle like the TX200 Mark III, they demonstrate how effective it is.

Piston weight

When the weight of the piston is changed you don’t really change the power as much as you bias the gun to lighter or heavier pellets. Heavy piston equals heavy pellets and so on. All it does is keep the piston from bouncing off the cushion of air that it compresses.

What can be done with this knowledge?

Here is where Mr. Wizard wows the kids. Knowing all the above, you can build a spring piston airgun that’s easy to cock because it has a light spring, yet it generates lots of power because of a long stroke. The TX200 approaches this ideal, but more can be done, I believe. Pay attention to dampening vibration, and such a gun would become a world-beater.

Or, a dual-power spring rifle could be built. It could generate low power (5 foot-pounds) by stopping at the first detent and high power (18 foot-pounds) by stopping at the second detent. Like the P1, power would be controlled by the length of the piston stroke. By using a progressive rate mainspring in conjunction with the cocking mechanism, the cocking could be very light (15 lbs.) for low power and heavier (30 lbs.) for high.

I hope this has answered some of your questions about how spring-gun power is controlled. We will look at pneumatic powerplants next. I might be able to do a third report on CO2 powerplants, though I haven’t decided yet.

65 thoughts on “Methods of power adjustment — springers: Part 1”

  1. Very informative. I look forward to the next in the series.
    I think a co2/dual fuel report would be a good blog.
    How does Crosman determine the optimum size/tuning for co2 as opposed to air, as the co2 molecule is larger, and at a lower pressure than air in say the Discovery or Maximus.

    Or pertinent to their latest release, the Wildfire, running co2 at 850-1000psi, what is entailed to get what is technically a 1077 to function on air from 2000 psi down to about 950psi?

    Also, I have a question.
    At Crosman’s main production shop, (not the custom shop), do they assemble the guns on an assembly line, or does one technician build a gun from a bin of parts from start to finish?

    • 45Bravo,

      We are stepping on BB’s next report on controlling PCP power, but with the Discovery and likely the Maximus, the transfer port is sized large enough for CO2. One of the guys I met at the GTA Fun Shoot has a Disco Double that he made a smaller transfer port for and actually increased the power and efficiency. Now by making it smaller yet, he could reduce the power and air consumption. He also had a modification that allowed him to adjust the striker spring tension. Now the Marauder has an adjustable transfer port.

    • 45Bravo,

      I don’t know the details on the Wildfire yet. As soon as I do, I’ll tell everyone.

      As for the Crosman assembly line, it’s a mix of things and probably unlike anything you have every seen. I wish I had pictures. We filmed it for American Airgunner, but the footage was never aired.


  2. I know other countries also have different classifications of firearms that vary in degree of regulation, and this is the same situation in Canada with air guns.

    Air guns that exceed 500 FPS are still legal – but they are regulated by the same laws as the firearms of their class (rifle/pistol). In the case of high power spring guns, this often leads to the sale of both full power and lower-power guns of the same model. Since many hunters are likely also licensed firearms owners, they have little to gain by buying the lower-power models. In other cases, the sub-500 FPS mean that hobbyists can experiment without having to go through the process of obtaining a license.

    • FYI –
      For all Pistols in Canada there are 2 limits which exist – velocity and energy.
      If it is under 500 fps and ALSO under 5.7 joules of muzzle energy- it is an uncontrolled firearm and needs no special licenses to own/buy/use one.
      If BOTH over 500 fps and 5.7 joules of muzzle energy – it is considered a full firearm and you need an R-PAL (Restricted Firearms License) to own/buy/use one.
      This you can have a .50 calibre pistol shooting at 495 fps with 50 joules (or more) of muzzle energy and it would be considered an uncontrolled firearm and you could own/buy/use it with no special license needed.
      And you could have a Steel BB pistol shooting 5.1 grain BBs at around 600 fps and it would also be an uncontrolled firearm because the muzzle energy it still below 5.7 joules.
      Confusing; I know!

  3. B.B.,

    5 STARS! Excellent article and good refresher. One question : Is there any rifles with a “progressive rate mainspring” in current production?

    I brought that up in the past by using the analogy of an automobile strut spring. At the time I noted too that the wire diameter was progressive, the pitch varied over the length and the diameter of the overall coil also varied.

    In the case of air guns, I would imagine that only the pitch varies, while coil diameter and wire size remains the same.


  4. BB,

    I think a multi power sproinger would be a great product as long as it was made with quality in mind. I myself would not be too concerned with cost if it was top shelf like a TX200 with a nice walnut stock.

    Would it not be nice if Crosman did build a sproinger with a nice trigger?

    • RR,

      That would be interesting. Though I think a multi-pump would fit the bill better on a varied power air gun. For someone that does pesting and only had a springer, it would make the difference between taking a bird out of barn rafters vs taking the bird out, or missing (and) putting a hole in the roof as well. The idea has merit too in that one gun could be cocked by a youth or an adult.

      • Chris,

        Or better yet, a PCP with a power adjuster. Back to the sproinger though, I truly think there is a market for a variable power sproinger. To have a nice quality sproinger that you could leisurely hunt feral soda cans on a nice sunny afternoon and then take out for some serious small game hunting would indeed be the ticket. I just hope someone like Weihrauch or Diana or Air Arms comes out with it before Crosman does.

        As for our conversation yesterday concerning a light, quality PCP for hunting, one that you might want to put on your short list is the Daystate Huntsman Regal XL. It is on mine. Another that is made in the same factory is the Brocock Compatto, also on my short list.

        As far as FX is concerned, I am considering the new Streamline and the Impact.

        From RAW I would get another HM1000X in either .25 or .30 with a walnut sporter stock. They are not light, but they can reach out there pretty far with amazing accuracy.

        • RR,

          Thanks for the ideas. I will look them up. I just can not (ever) see plopping down 1500+ for one rifle.

          Besides, you need to get that tank, pump and chrony bought first. Hopefully the Maximus will be sufficient for my lightweight 15-40 yard “critter getter”. It should be here today so I will be getting it set-up and shoot some this afternoon (indoors).

            • RR,

              REALLY?,…. REALLY???????,……. I have (just) unpacked the Maximus and now I got to hear about THIS!!!!!! 😉 I do like. Cheek riser, repeater, 3000, 900 fps in .22. 8.5# is a bit on the heavy side though. Thanks for the heads up. Doc Holiday posted a link below.

              Should have something to report on the Maximus later or tomorrow.

                • RR,

                  Me happy. A few flaws, but worked around them. Sight in with 5 shots and 5 more shots were .300″ at 41 ft.. Scope good too. 6×40 with front A.O.. Picked up notebook paper lines at 41′ just perfect. Long looks good too. It does have a good “pop”,… which I like. More tomorrow.

                  p.s.,….. you ain’t gettin’ it! 🙂

                  • Chris U
                    So you got your Maximus.

                    First question I have. What brand scope is it. A Centerforce?

                    Second question. How’s the trigger?

                    And last one. Did I get the only accurate .22 caliber Maximus in the world or is there more than one. 😉

                    • GF1,

                      Center Point. Only have 10 shots through it. I can live with the trigger. Accuracy was as good as the TX and LGU at 41′. Will give the full “low down” on 1/12 blog, probably afternoon.

                  • Chris U
                    Yep that’s what I meant on the scope name. My phone changed spelling again. There’s a racing clutch for stick shift cars that called a Centerfire. So of course my phone thought I spelled Centerpoint wrong.

                    But ok will see what more you have to say about the Maximus.

  5. Well BB, manufacturing air guns is a lot more complex process than I was led to believe, but anyways, wasn’t there a guy who built a larger Beeman R1 for more power, and increased nearly everything ? Why was not he successful?

  6. I am happy with 14 fpe at the muzzle. BB, what do you reckon would be the power required to penetrate a 1 inch thick softwood (like pinewood) from 5 feet with the most pointed pellet possible with a .177 rifle? The arms act says that if the pellet exits the other side, it is a firearm. Ordinary citizens are unable to perform this test and I am asking you for a calculated guess.
    The arms act which banned .22 in August and limited to 15 fpe has lapsed.

  7. B.B.

    Very interesting article! Progressive mainsprings-If Air Arms has so much success with them, why aren’t more other manufactures copying the idea? Imitation and all that……….please explore this further at some point.

    For 2 hypothetical air guns with with different bores and stokes, but the same swept volume, same spring, same transfer port size; would they shoot the same speed?

    Lastly, for air gun manufactures that sell in all different regulatory environments, couldn’t they just change the location of the trigger seer detent on the piston? Having different pistons for different regulations would seem to be the easiest way to only make one change in order to be in compliance?

    Sorry to be so long winded,


  8. BB,

    I love these reports, back to the basics is always interesting. Thanks.

    Actually, there is much more room to export than you describe. For a comprehensive survey of current laws regarding airguns in Europe see: https://en.wikipedia.org/wiki/Air_gun_laws.

    For instance France and Holland would fall in the range for export as decribed by the UK market. Holland even has no restrictions.

    Export is quite well possible, but it needs a good knowledge of law and language to succeed,



      • August,

        I just scanned that Wiki article and saw one error. They say it is legal to own a 5.5mm airgun in South Africa, but when I worked at AirForce Airguns we could not ship 5.5mm Condors there because they were considered firearms. Only .177 caliber was legal.

        The law may have changed, because they are always in flux, but I know the .22/5.5mm used to be restricted.


        • BB,

          I subscribe to a youtube channel, AirArmsHuntingSA, that shows airgun reviews and hunting in South Africa. He usually hunts with a 22 but I believe I’ve heard him say that he has an FAC (firearms certificate) or the South African equivalent.


  9. Greetings BB and Fellow Airgunners
    Thank you for such an informative blog about controlling the power of a spring piston airgun to comply with the laws of various countries. As you stated, here in Canada we are limited to 500fps, and 5.7 joules without the need of a PAL(Possession and Acuasition License).
    I often wondered how the Weihrauch HW45 worked with the dual power cocking system. Thanks for clearing up that mystery.
    There is another way to limit the power of a full power airgun without resorting drastic changes. Crosman limited the speed of some of their full power spring piston airguns to conform with Canadian airgun law simply by drilling a hole through the head of the piston, and piston seal. This let enough excess compressed air to escape through the hole, and into the rear of the air chamber to comply with the 500fps limit. I have heard of people using putty, crazy glue, or epoxy to seal the hole to obtain full power. Of course they risk arrest, a hefty fine, and/or jail time for illegal possession of a firearm should they be caught.
    I’m looking forward to reading similar articles on PCP’s, and CO2 powered airguns.

      • Welcome to the confusing world of Canadian airguning! This post is a little long. We didn’t actually have a power restriction until about 2001 or so. Before that we just had a 500fps rule and we figured the velocity was set using Crosman pellets. We all thought it was Crosman because that was the brand you could find at every sport shop or hardware store. Then one day the Royal Canadian Mounted Police (RCMP) started testing airguns with the new Marksman Laserhawk pellets. If you recall they were half plastic and weighed about 5 grains in .177. As you could imagine all kinds of air pistols could suddenly be considered restricted firearms as they blasted out these light weight pellets! Luckily someone at the RCMP decided that wasn’t right and they came up with the 4.2fpe limit. The thing is that at the time the wording for the limit was 500fps AND 4.2fpe. So your .22 rifles and pistols that we under 500fps were still fine at 7.8 fpe because although they surpassed the 4.2fpe limit they didn’t exceed the velocity limit. Both had to be exceeded to be considered a firearm. The odd thing is that they still did not specify a weight for the pellets that airguns were to be tested with. We figured they went back to the 7.9gr for .177 and 14.3gr for .22. So there is still a gray area that I will mention later. More recently the wording on the RCMP website has changed. The wording for the limitation is now 500fps AND/OR 4.2fpe but this does not seem to be correct and has sparked a lot of debate on Canadian forums. Changing the wording to and/or would indicate that you only need to exceed one limitation not both. Currently though, if you buy a .22 Weihrauch air rifle specifically detuned for Canada from one of our vendors it will chrony at about 495fps with a 14.3 grain pellet. The same goes for most of the other brands. So in the end, basically, at the moment, if you stick to the 500fps rule using Crosman pellets you should be fine. One company that has taken advantage of the no pellet weight being indicated is Diana. Airgun velocities are no longer tested in Canada, the manufactures data is used instead. As no pellet weigh is specified Diana pistols such as the P5 (.177) and LP8 are unmodified for the Canadian market. The velocity figure was set using a 9 grain pellet to keep the velocity figure under 500fps. With their .177 rifles they set the velocity using the 10.5 grain H&N Barracuda according to the sticker on the box your rifle comes in. This basically allows them to send unmodified rifles that were originally made for the German domestic market to Canada. Some vendors no longer carry the “detuned” Diana rifles as they think this practice is a little sketchy. Full power versions are still available for those with a PAL.
        One problem with using the manufacturer’s velocity numbers is that they are not always honest. When the Crosman 2289 first came out Crosman advertised a velocity over 500fps but in reality it was more like 475fps. Due to the advertised velocity rather than the actual velocity Crosman had to modify the 2289 if they wanted to sell it in Canada. At first they restricted the transfer port and then later switched to using a bleed hole just below the valve stem. The velocity was now down to about 395-405 fps and the 2289 got a bit of a bad reputation. They probably would have sold more in Canada if they stuck to the actual velocity. On the other hand they probably sold more in the US using the advertised velocity.
        As far as detuning spring guns goes there are a few methods used. HW rifles have lighter springs, Crosman short strokes their rifles, Norica drills a hole in their pistons. Back when the BSA Scorpion was a spring pistol instead of a PCP rifle they had different springs too.
        The HW45 is an interesting case. I bought my first HW45 in 1999. You could not buy a .177 HW45 in Canada at the time, only .22. The pistol has only one power setting and gets just under 6fpe. I bought my second HW45 in 2005. It was a .22 HW45 STL and other than the finish it was the same as the first. When the HW45 Silver Star came out (2009?) it now had the two power settings but was still only available in .22. Finally a year or so later when the Black Star came out we finally started to see the .177 HW45 in Canada. Mine does have two power settings but I never use the lower one. The stroke is identical to the full power .22 versions I have and it is putting out 4.1fpe. I guess it took a little longer for the engineers at HW to decide how to tune it! 🙂

  10. Cheers from Brazil, BB! The Government controls airgun power by restricting calibers (6mm max)… pretty stupid, in my opinion. But… what country has the most stupid gun laws on the planet these days? I think we would be on the top 5 for sure!!
    About the different power strokes, do you know any rifle that has two (or more) detents?

    • Fred,

      You know, when I wrote this report I was thinking that Webley once had a rifle with two detents, but I looked through the new Blue Book and couldn’t finds a mention. I thought it was selling in the 1970s.

      Perhaps Dom or one of our other UK readers will know.


    • India has the most stupid gun laws my friend!!!
      I think we will be in the first place!!
      Even in this day the power of air rifles is tested by deal wood test. And I have seen wide variations, sometimes a Diana 350 magnum is passed , sometimes a .22 shooting 650 fps is detained. And ,, if you fail the test ,you are treated as same as having a firearm, no distinction between AK 47 and Diana 350 , you get 7 years rigorous imprisonment.!!!
      If you still don’t think it is the most stupidest,, I will give you more clauses of the arms act to prove my point.

  11. BB

    Must reading for anyone hooked on air guns. I am impatiently waiting for the next and next reports. So much to learn. I do have one question. Can a built in sound suppressor reduce both energy and velocity without adversely affecting accuracy?


    • Decksniper,

      I don’t know that a suppressor/silencer reduces velocity, except indirectly. Because you have to shoot subsonic ammo in a suppressed gun if you want it to be quiet, the velocity has to be slower. But I don’t think the suppressor has much to do with it.

      As for accuracy, when I tested my suppressed 10/22 (screw-on silencer) the accuracy was always a little worst with the can installed.


  12. B.B.,

    This is obviously a compelling topic. Your report makes me appreciate the painstaking design elements — each working in concert with and affected by each of the other design elements — of the very best springers. The difference between sophisticated powerplants (TX200, HW77/97, late 20th Century 10 meter springers, perhaps the new Umarex Throttle) and blood simple ones (early Xisico, Industry, etc) is indeed a huge.

    Consider the potential pittfalls: the Steel Dreams rifle that lost potential power in part because its strong and long spring was too heavy, the reduced-power Diana K98s for restricted markets that have transfer ports so small that the piston bounces like a tennis ball, ultra-magnum breakbarrels with spring strokes so long that their lock time can be measured with a calendar, and so on.

    Every time I pick up my TX200 from now on, I will for a moment consider just how much of a design marvel it is.

    Thanks for this report.


  13. BB,

    I am really intrigued with the possibility of a quality sproinger with variable power. Are you aware if there are any manufacturers looking at that possibility? Perhaps when you go to the SHOT Show this year you will take the time to discuss this possibility with Weihrauch, since they have some experience with such, and also with some of the other manufacturers?

  14. BB

    Here’s a question for ya…you touch on dual power

    You reference the P1. Which is an obvious choice when discussing a piston gun that can produce two different power levels. But what about the lesser known Dual Magnum that Beeman had? I believe it was a VERY small run, less than 150 is what I was told by a former Beeman employee. I had the opportunity to shoot one once, the owner said it shot around 20 FPE with a single cocking stroke, and just under 30 with two. It was a gas ram if I recall correctly. I don’t believe this was a dual pistol design like a Whiscombe….but I never asked the owner how it worked. If you have any info, was this like a P1 where the first cocking stroke only takes the piston back so far, then the second even further? Or something different entirely?

    Thanks and see you @ SHOT

      • It was a gas ram, believe used the Theoben Ram. May have even been released under their name for a time. Poking around, can’t find any pics. But it had a laminate stock (similar to the RX2). Also had a pop up breech, which was kind of an oddity.

  15. B.B., Thank You so much for this report. It’s always good to be reminded of how it all works. I do hope you do the Pt. 3 to include C02’s also. I’ve never owned a P1, but have always liked the idea of the “dual” power level with just one cock.
    Off subject, all the news leaking out on upcoming air guns has me like a kid on Christmas Morning. Air guns just seem to get more exciting all the time. First the Crosman 1077 in a PCP! And now Umarex sounds like they have a real winner coming in PCP. https://hardairmagazine.com/news/umarex-gauntlet-sets-new-standard%e2%80%a8-pcp-air-rifle-performance/
    Thanks again for the reports.

  16. New here.
    Great blog…:o)

    Living in Denmark with hunting grounds in both Denmark and Sweden, I would like to update your information, regarding the legislation on airguns here.

    You say, that ao Denmark limit airgun velocity rather than energy.
    Well, that is not really so.

    Since 2012 rules were changed from having absolutely no restrictions on spring and PCP airguns to the following:
    If you have a Hunters Licens / Fire Arm Certificate (FAC), you can still buy any airgun unrestricted.
    If you do not have a FAC, you are only allowed to buy airguns with a caliber of .177 or less.
    It’s netiher velocity nor power.
    Even though it seems rather stupid from a safety point of view, it is still possible to buy a very powerful +25J .177 airgun withoult any restrictions, whilst you have to have a FAC to buy a powerless .22 or above airgun.

    In Sweden there is a 10J limitation, no matter which caliber, if you do not have a FAC.

    Anyway, this only goes to prove your point, that there are an endless combination of restrictions, that an airgun manufacturer has to consider, before introducing an airgun to a new country.

  17. Very thorough. I don’t think I saw the phrase “swept volume” in the blog, but it is consistent with the rest of the discussion.

    Gunfun1, I didn’t read the pellet reloading article carefully. Judging from the centerfire case, I assumed that the pellet was shot in a larger caliber. However, the fact that it fit into the case mouth means that the caliber must be small. Anyway, another obstacle for me is the issue of power. If I want more than an airgun can offer, I’ll use a firearm rather than try to create a hybrid.

    As for rapid fire, I’m not talking about hosing the target. I’m thinking more of how accurate fire can be pushed to the very cusp of automatic fire, so you will have both firepower and precision. That would be a formidable combination. And I suspect that is why the assault rifle design has been so effective. It is set up to find that cusp and adapt to circumstances as the first smart weapon.


    • Matt61
      I believe the idea of the pellet firing cartridges was invented to let people practice with the firearm they shoot. Less power for shooting indoors, quieter and cost less.

      I was just trying to think of ways to get more accurate results from it.

      And I would say maybe the 3 gun competition is similar to the type of rapid fire shooting your talking about. I do like that kind of shooting.

  18. Another method of reducing power is a small hole drilled in the piston. This allows a bit of air to got through instead of out the transfer port, reducing velocity. The problem with this is, the mainspring remains the same! More cocking effort
    A number of modders have found airguns with this and plugged the hole. Increasing velocity.

    Silver Eagle

    • Silver Eagle
      Titus brought that up about the hole in the piston above.

      To me I would not want that blow by. I would rather reduce power with different size coil diameters and spring length. Or increasing power too.

  19. BB,

    On the longer stroke vs. bigger bore points, don’t you think it is possible that longer stroke is preferred mainly because it allows more reuse of components in a design? Ie some tubes and linkages may have to be altered, but most parts can be identical to or at least come from the same stock as a shorter design.

    My objection is that lengthening stroke noticeably increases “lock time” whereas increasing bore size either keeps it the same or could possibly reduce it by shortening stroke. Yes, there is a practical limit, but due to the geometry a small bore increase results in relatively more volume. On the down side, almost every part needs to be redesigned.

    Just wondering about your thoughts on this.

  20. Great article BB. I have learned so much since joining this blog. I have a Gamo Shadow Sport spring air rifle. I watched your video on the artillery hold for shooting springers accurately. Awesome video! You are the MAN!
    I purchased that rifle for my father-in-law. When he passed it was retuned to me. It came with the scope installed. I’m looking forward to shooting it with your advice. I’ll bet my groups shrink significantly!

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