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Sig ASP20 rifle with Whiskey3 ASP 4-12X44 scope: Part 9

Sig ASP20
Sig ASP20 breakbarrel rifle.

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7
Part 8

This report covers:

  • The test
  • Sig Crux Pb domes
  • JSB Exact Jumbo
  • JSB Exact Jumbo Heavy
  • Muzzle report
  • Sig Crux Ballistic Alloy
  • Discussion
  • Summary

Today we look at the velocity of the Sig ASP 20 .22-caliber breakbarrel pellet rifle. The ASP20 has a gas spring and readers are concerned that it may have leaked down over the nearly five years I’ve had it. Now we find out. This is in preparation for the first test of the Integrix 2-12X36 scope that will be mounted on this rifle next.

The test

I have all four of the pellets that were used in the 2018 test, so I used them all today. You will see a comparison of the the velocity averages they gave in November of 2018 and the velocities they gave today.

Sig Crux Pb domes

The first pellet tested was the Sig Crux Pb dome. They appear to be no longer available. In December of 2018 this rifle shot ten of them at an average 856 f.p.s. the spread went from 850 to 868 f.p.s. — a difference of 18 f.p.s. At that velocity this 14.66-grain pellet develops 23.86 foot pounds of energy.

Today ten Crux Pb pellets averaged 784 f.p.s. The low was 774 and the high was 790 f.p.s. — a difference of 16 f.p.s. At the average speed the Crux Pb develops 20.01 foot pounds of energy.

The average velocity has decreased 72 f.p.s. over four years. The spread has remained more or less constant.

The Crux Pb pellets loaded very hard. I had to push them into the breech with a ballpoint pen to get their skirts below the end of the barrel.

JSB Exact Jumbo

Next to be tested was the 15.89-grain JSB Exact Jumbo dome. In December of 2018 ten pellets averaged 830 f.p.s. The spread went from 824 to 835 f.p.s. — a difference of 11 f.p.s. At the average velocity this pellet developed 24.31 foot pounds of energy.

Today the same Jumbo pellet averaged 767 f.p.s. The low was 762 and the high was 777 f.p.s. That’s a 15 f.p.s. difference.  At the average velocity this pellet developed 20.76 foot pounds of energy.

The average velocity has decreased 63 f.p.s. The spread is close enough to say it remained constant.

JSB Exact Jumbo Heavy

The next pellet tested was the 18.13-grain JSB Exact Jumbo Heavy. In December of 2018 ten of these pellets averaged 776 f.p.s. The spread went from a low of 771 to 780 f.p.s. — a 9 f.p.s difference At the average velocity this pellet developed 24.25 foot pounds of energy.

Today the same pellet averaged 699 f.p.s. The low was 690 and the high was 708 f.p.s. That’s a difference of 18 f.p.s., which is double what it was four years ago. At the average velocity this pellet developed 19.67 foot pounds of energy.

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Muzzle report

I measured the loudness of the rifle at this point. It is reasonable quiet, at 98.9 dB.

Sig Crux Ballistic Alloy

The last pellet I tested both in December, 2018 and today was the Sig Crux Ballistic Alloy. These also appear to have disappeared from the market. They also pushed into the breech hard, requiring the aid of a pen. In 2018 this 10.03-grain dome averaged 1064 f.p.s. The spread went from a low of 1056 to a high of 1070, a difference of 14 f.p.s. At the average velocity this pellet developed 25.22 foot pounds of energy.

Today this same pellet averaged 982 f.p.s. That’s 74 f.p.s. slower today. The low was 976 and the high was 987 — a difference of 11 f.ps. which is very similar to before. At the average velocity this pellet generated 21.48 foot pounds of energy today.


You can see that the ASP20 has lost power over the four years I’ve had it. The loss has been around 4 foot-pounds, which works out to different velocities, depending on the weights of the pellets being tested.

In 2018 this rifle cocked with 33 pounds of effort. Today it cocks with 30 pounds. The trigger pull was adjusted last time, but I set it back to where it was at 1 pound 9 oz. for stage one and two pounds exactly for stage two. It remains at those settings today.


I find my .22 caliber Sig ASP20 rifle to be accurate, gentle and pleasant to shoot. It has lost power over the past four years, so I will keep an eye on it as time passes. I think if I shoot it more the power loss may slow or even stop, but only time will tell.

40 thoughts on “Sig ASP20 rifle with Whiskey3 ASP 4-12X44 scope: Part 9”

  1. B.B.,
    She’s still got some decent power to her, but is there any way to put her back to where she was?
    I’m thinking of the HW90…it would be nice if you could do the same here.
    Blessings to you,

    • Dave,

      There is undoubtedly a way to re-pressurize the gas piston as Ed Schultz would not have left that out. But who how and where are things I don’t yet know.


      • It sounds like a time to contact Ed. I would not bet money on it being rechargeable. Something that is rechargeable like a Theoben is expensive and may have been overridden by the accounting committee. It was probably anticipated that the gas sproing could be replaced from spare parts, but that was before Sig decided to dump it.

        Maybe you can replace the gas sproing with a real one.

  2. B.B.

    How appropriate, you test pellets that are no longer available in a gun that is no longer available!
    Perfect symmetry.


    PS Some people believe that gas spring guns should be stored with their piston stem facing down.
    Is that how this gun was stored?

  3. BB,

    This does not bode well for the use of gas sproings. This is also not the first time I have heard of these things leaking down. Will storing them in a certain orientation help? I seriously have my doubts, but though I am indeed brilliant, there are a few things I do not know. There is not likely any documentation to support this thesis.

    Yes, metal sproings can and do experience “fatigue”. At least metal sproings can be easily modified and/or replaced, most of the time anyway. Try and find that particular gas sproing now.

  4. Hmm. Maybe it would be useful for other ASP20 owners to remind us what velocity they are getting with the pellets they use and whether they experienced the same decrease over time.

      • B.B.,

        So far I have seen no degradation in performance in either the .177 and the .22 rifle. I have the initial numbers from the LabRadar and can do a compare anytime i set up to shoot. But havent recently shot and used the LabRadar because the rifles both still shoot to the expected POI according to my D.O.P.E.
        (Data On Last Engagement) to include Elevation turret settings. I’m not using the bullet drop compensating turret(s) on either rifle because of personal preference to use D.O.P.E. instead. The Distance/Elevation Compensating turrets do work well within a narrow band of pellet weight/form factors.
        Not at all for Boolits (Slugs) in my experience and that is exactly as it should be.

        More next time i shoot the ASP20’s with the LabRadar set up.

        I will do a Meteorological (Atmospherics) factors comparison as well if the conditions pan out.


    • Roamin & all

      Here are some before and after velocities for my 2 year old (at that time) .177 ASP20. Having just bought my first chronometer I measured velocities for several guns on 12/2/2021. My ASP20 with Baracuda 10.65 grain pellets averaged 863 fps and 18 fpe. Over the next few weeks I began having Sig accuracy problems. Cocking effort got less and less so I got out the Caldwell. Velocity had dropped to 388 fps with the same pellet. On 1/10/2022 Sig authorized return for repair. On 1/21/22 I received my ASP20 from Sig Sauer Repair by UPS. Repair form stated the piston seal was replaced and rifle now shoots to spec. There is a reason I didn’t test the velocity after the repair to see if any slow leakage had happened in the first 2 years. These pellets were hard to seat. I was using credit card flat strips to flush the skirts even. My unproven theory is this technique was causing ill timed piston bounce. Maybe I’ve read too many Cardew books. I have not shot the Baracuda 10.65 grain pellets in this rifle since and I avoid any others that don’t fit reasonably well. I also got rid of the credit card strips.

      Does BB’s rifle need a new piston seal? I don’t know. Do car trunk gas springs leak over time? Not enough to matter. Do I wish there was a “real” spring in my rifle? Yes, providing accuracy is not compromised. I’m getting excellent accuracy with AA and JSB 8.44 grain pellets.


        • Shootski

          On a couple of occasions I put one drop of Silicon non petroleum oil in the air chamber. Although the manual does not comment on frequency I use the same regimen as on my other air/gas spring guns.


          • Decksniper,

            Thank you!
            Let us hope your experience was simply the case of the Bathtub Curve with its Infant Mortality being the case.
            I wonder if Tom used the same Chronograph to do both tests? I also wonder about Density Altitude being at least a contributing factor.
            That is one of the reasons I use D.O.P.E. to follow performance numbers.


  5. The “no-deal” reason for FM’s no-purchase of the ASP20 was finding out SIG would not make spare parts available to owners. There are aftermarket breech seals being made for it; maybe replacing these would help somewhat with velocity loss but remember this is advice from an amateur who’s never handled/shot this rifle.

  6. So much fight over a lost cause. Do we really need an expertly designed product that was dropped from production by its own makers? Certainly not me. A rare bird shot down. What a pitty, especially for the company that made it. On the other hand the original Sig Sauer might had treated their customers differently.

  7. I wonder if anyone can imagine the seemingly impossible:
    Can you imagine the SigSauer ASP20 purely as an airgun?

    I have several airguns that qualify, simply because they survived their manufacturer. Imagine my political misgivings about a vintage Giffard for example and the impact that would have on future Giffards? 🙂
    Occasionally I remind myself of the bigger picture, you know, one of those pin-sharp, high resolution stunning photos in which, I too, appear…
    … as a pixel, because it helps me visualise my importance! 🙂
    So, for me, my ASP20 in 4,5mm (0.177″) calibre means, it’s the one with the silencer that sticks up above the rest. It really looks a big black beast!

    Despite showing an “F” in a pentagon, the impacts on target sound quite powerful.
    Anyway, to realise the accuracy potential that extends beyond my eyesight, I need an appropriate visual aid, ie a scope. 🙂

    My SigSauerASP20 is one of my fun 50metre (~54.68yd) plinkers that I realise I want to play more with… 🙂

    • hihihi,

      “Can you imagine the SigSauer ASP20 purely as an airgun?” YES! hihihi you have cut right to the nut! I just got back from the shop for emissions and safety checks (like TÜV) after my 2001 SAAB 9-3 VIGGEN
      (THEY DON’T MAKE THEM ANYMORE either) and only made 1,500 or so examples, mine is a Convertible so even rarer, and I drive it almost every day mostly with the top down. Even in Winter; love those MAXIMUM Swedish heaters, and my wind block over the rear seat allows me to go (sans aquarium look) with all my side windows down.
      So what does that have to do with airguns like the SIG ASP20? Well you seem to know but others let their damaged Id get in the way of enjoying all things enjoyable.
      They spend lifetimes muttering about how unfair it all is. How does shootski compensate? He has walked in The Valley of the Shadow of Death numerous times; after a few you learn what Truly matters.

      Here endeth the Wednesday Sermon on the dirt bump.


      • In my case, the mutterings have a different context…when I was first getting back into airguns couple of years ago, I was researching all things airgun and realizing there is a lot more to this hobby than Crosman, Daisy, and Gamo. I saw an article by this guy named Tom Gaylord in Firearms News about his visit to the Sig factory and then a sequel article about the ASP20. I was really enamored with that story. That led me to this blog and my new friends here. So the ASP20 in a way brought me here. It’s just a shame that such a groundbreaking airgun just vanished without a word from Sig. Is it weird to have nostalgia for an object one has never seen? Probably, but my kids think I’m weird so I guess it’s true. I have recently seen one sell for over $1000! A Sig ASP20, not a kid.

        Moving on, I just won an auction on a Winchester 333 for $175, so my Id is still intact! And now I have more of my bucket list filled.

        • Roamin Greco,

          I certainly hope at that price the buyer(s) were Collectors! The guns are not worth that much money to a shooter.
          Nice find at a good price.
          Are you going to shoot the Winchester 333 ({stage whisper} he asks) knowing full well the answer.
          I don’t do remote diagnostics and know i’m not qualified but I suspect your Id is intact too.


    • hihihi,

      I forgot to address the “F” in Pentagon Frei symbol that is on my ASP20s. I thought that mark was for Germany and indicated below 7.5 Joules; the firearm certificate/license power level? I know for a fact that neither of my SIG ASP20s meets that minimum.


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