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Ammo Air Arms S510XS Ultimate Sporter with Laminate Stock: Part 9

Air Arms S510XS Ultimate Sporter with Laminate Stock: Part 9

Air Arms S510XS
Air Arms S510XS Ultimate Sporter with Laminate Stock.

Part 1
Part 2
Part 3
Meopta MeoPro Optika6 3-18X56-scope: Part 1
Part 4
Part 5
Part 6
Part 7
Part 8

This report covers:

  • Background
  • The test
  • Air Arms 16-grain dome
  • First group
  • H&N Baracuda 15
  • Air Boss
  • Is BB shooting his best?
  • Discussion
  • Summary

Today’s report is really another test of the Apolo Air Boss .22-caliber pellet. But as Pyramyd AIR doesn’t carry the Air Boss pellets yet, I put it under the Air Arms S510XS Ultimate Sporter with Laminate Stock.


The S510XS is the most accurate .22 caliber precharged pneumatic (PCP) that I own, so I use it as a testbed. It mounts a Meopta MeoPro Optika6 3-18X56 scope with an illuminated reticle. When I got ready to shoot I discovered that the scope’s CR2032 battery had gone dead. I try to remember to turn off the scopes with illuminated reticles and this is a note to myself that I did indeed turn it off after today’s test.

I also didn’t bother sighting-in because the scope was already on at 25 yards in my December test of Baracuda pellets then and now. It was sighted low and to the right to preserve the aim point. They might have hit just a little lower today than they did then, but I did not adjust the scope.

The test

I shot from 25 yards with the rifle rested directly on the sandbag. I will have more to say about the rest in a bit.

I shot 10-shot groups with every pellet. After the smoothness of the TX200 Mark III with the Tony Leach kit it was a surprise that the S510 wasn’t as stable on the sandbag. More on that in a moment. Let’s get started.

Air Arms 16-grain dome

In the past the Air Arms 16-grain dome has been the most accurate pellet in this rifle. Back in October of 2019 this rifle put 10 of these pellets into 0.18-inches at 25 yards. In Part 8 of this report ten of the same pellet made a 0.193-inch group at 25 yards. I felt this was the right pellet to use as a baseline for today’s test.

First group

Unfortunately while shooting the first group I discovered that the S510 isn’t as stable on the sandbag as my TX200. It’s so tall that it’s top-heavy. The first group was larger than I would have liked as a result. Ten Air Arms 16-grain domes went into 0.486-inches at 25 yards. Look at the group. The first shot went high and to the right and shot number seven went low and right. The other 8 shots are in a tighter group that reflects the pellet’s true accuracy in this rifle, but it doesn’t matter because those two shots messed it up.

Air Arms S510XS-AA-16-group1
This group of 10 Air Arms 16-grain domes measures 0.486-inches between centers.

Stock Up on Shooting Gear

H&N Baracuda 15

The next pellet I tested was the new H&N Baracuda 15 that was the second best one in my test of Baracuda pellets then and now. It was only a little less accurate than the Baracuda 18 pellet, grouping 10 in 0.322-inches at 25 yards.

This time I adjusted the hold of the rifle by sliding my shooting hand forward until it was pressed into the rear of the sandbag. This was a more stable hold, though not as stable as the TX200 in that recent test. Still, I was able to keep the illuminated dot over the bullseye central dot most of the time. But by the end of this report I will prove to you that this is indeed a more stable hold.

Air Arms S510XS Barracuda 15 group
Ten Baracuda 15 pellets made this 0.329-inch group at 25 yards. Now we’re cookin’!

Air Boss

Now for the group that this whole test is about. But before we look at the group, so many of you asked whether these pellets are hard lead or soft that I did the very unscientific fingernail test. The pellet was scratched by my fingernail. In my opinion it is dead soft.

And what about the accuracy, now that BB is shooting his best? Ten Air Boss pellets went into a very round group that measures 0.478-inches between centers.

Air Arms S510XS-Air Boss group
When the rifle was held steady ten Air Boss pellets went into a very round 0.478-inch group.

Is BB shooting his best?

Okay I said I would get to this. I knew the Air Arms 16-grain domes were more accurate than we saw in the first group. So I shot another group of them. This time ten made a 0.241-inch group at 25 yards. That is the best I could do on this day, folks.

Air Arms S510XS AA 16 group
And here is the proof that I’m holding the rifle in the best way. Ten Air Arms 16-grain pellets made this 0.241-inch grouip at 25 yards.


Today the Air Boss pellet made the largest group of the three pellets tested. The other two pellets were known to be good in the S510, so my conclusion is the Air Boss isn’t quite as good in this rifle as either of them.

In the test with the Dragonfly Mark 2 the Air Boss was the second best pellet tested. And from that, plus what we see today, my conclusion is that the Air Boss is a good pellet that will vary from airgun to airgun.

Two tests hardly establish anything, but they do point us in a direction. And that direction seems to be that the Air Boss is a good pellet. I want to try one more test with these pellets in the Sig ASP20 breakbarrel. I only got a few Air Boss pellets in each caliber, perhaps 40-50 or so, so my testing of them is limited.


It was nice to see some new pellets at the SHOT Show, and I still have both .177 and .25-caliber Air Boss pellets to evaluate. We will look at all of them over the coming weeks and months.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

46 thoughts on “Air Arms S510XS Ultimate Sporter with Laminate Stock: Part 9”

  1. BB,

    Despite it being unscientific it’s good enough that it can be scratched with your fingernail. The pellets are so new they haven’t had much of a chance to oxidize yet. You wouldn’t happen to have a .22 PelletGage on hand to compare the relative head sizes of the three pellets would you?


  2. They are off to a good start.

    After the Dragonfly test, I reached out to the company through their website, trying to buy a selection of their pellets in both 177 & .22 caliber to test in the Air Venturi Avengers. But I haven’t heard anything back from them yet.


  3. It looks like another pellet to be added to the collection. I have amassed several new pellets in recent times, most in .22. I need to pick up a couple more and then have a shooting party, pull out all my airguns and see who likes what. Just the sproingers will keep me busy for a while. Then tuning in the PCPs will keep me busy for a bit. Now if I can just get some warm, calm weather.

    I am really quite jealous of those who have indoor shooting ranges.

  4. Since we are talking about a new pellet there is something I have been thinking about.
    I wonder what would happen if one of the bullet/slug makers would put a o-ring groove towards the front of the bullet and at the rear also then put a o-ring on both grooves. That way the o-rings would be the only surface that would contact the rifling in the barrel or the smooth bore barrel.

    I wonder if they would be accurate.

    Also the metal part could be made out of lead or steel or aluminum or brass or even plastic. Also they could produce them on a machine like we do at work out of 12 foot long barstock. And our machines produce from 3 to 8000 parts in a 8 hour shift. And it would be a very simple part to make. The bullet/slug.

    Been wanting to mention it but I keep forgetting.

      • Yogi
        You don’t experiment much do you. You haven’t shot any .25 caliber and up big bore pcp’s have you. They make big power. And remember I only need to get those o-rings to last one shot. I just want to mainly get the slug/bullet out the barrel as true as I can and consistently. I’m thinking the o-rings with a smooth bore is going to work well. With a rifled barrel still not sure what will happen there.

        Oh and you mention a lead sealing ring. We have made 20, 25 and 30 mm bullets at work throughout time. They used a lead sealing ring. Then I mentioned the copper ring. Those were used for the 430 grenade launchers. So yes could work. But if you think about it that’s what the head diameter and skirt does with a pellet. A slug or bullet is different but basically seals like a lead seal your talking about.

        Read my reply to MisterAP below. And stop thinking spring gun’s for a change will you. 😉

      • Yogi
        And to make it clear I would use a few drops of silicone oil on the o-rings and make sure the o-ring was lubed all the way around.

        And no not any petroleum based lubes. You know how the barrel looked on Elmer’s barrel when he was hunting that rascaly rabbit Bugs Bunny. (split open like a banana peel) Yep I could see some major detonation happening if you used the other oils besides silicone oil. Maybe not but I bet so.

    • FM
      I could probably make a couple handful of them out of some scrap parts they throw away and give it a try. First things first things got to settle down at work and home a bit. Gunfun1 has been in overload mode for awhile.

      • Please use one with a micro verticle adjustment like my gun rest has.
        A bipod with a thumbwheel? Do I need to make one ?
        I am getting 80 shots @770fps with .22 FTT , 5 second spread, 2 second deviation. Prod with regulator, 1.6k output, 13cu bottle, factory barrel. I want to try a new production Prod barrel before I pay for a custom LW.
        Compared to my .25 Marauder, not as rock steady shooting platform either, but I will try some of these pellets you are using. I can cover most of the groups with a nickel at 47 yds, the Mrod is better tho.
        The .22 are easier to load.

          • Hajimoto tuned regulator from Jefferson state airguns. Hajimoto is the go to guy for the Gauntlet aftermarket, he carrys some stuff from them. The regulator comes with a wrench so its easy to go up or down in pressure, but I did have a drop down fitting for it already on with a crappy reg. I lightened the hammer about 30%, and went up to.30 for the hammer spring diameter. The probe is turned down, I slightly oversized a blue crosman t.p., opened the barrel port. The valve poppet stem was turned down, valve bores opened. I have no preload on the H.S., about .030 gap, but a few turns of the adjuster and it goes up quickly. I stop at 880 fps, it has a short barrel, too hard to cock,
            So, its maximised now for targets and very light pesting. When I tried cuda’s@21grns, the velocity fell to 660fps. The gun I want probably cost a little bit more than I have in it, still, I learned that much!

        • 1stblue,
          Wow. Thanks for the details. Lots of good stuff there. I have considered doing some simpler mods to the power plant of my Prod. But maybe it is better, for hack like me, to get an airgun that is offered with the capabilities that I now want. Such as an FX Dreamtac Compact in .22 or .25. – Don

          • I feel like it is most important having the predictability of the regulation that helps eliminate changes in point of impact. My Prod carbine with my custom lightweight stock is much lighter and handier than a .22 custom shop regulated marauder rifle, gets the same number of shots at only 10% less power. And it has the classic crosman pistol grip, which I like. The other thing is it gives me a good reason not to drop 2K on the FX Impact!
            Best, Rob

        • Rob,
          I agree that light weight is important. I am thinking that adding a reg allows a hammer spring setting that avoids the hammer bounce issue and gives more consist shots. A slightly larger transfer port would allow for a lower pressure tune or a higher power tune with the 11.75 GTOs that I use. 12-18 ftlbs is fine for my use. The reg, fill port with gauge and shroud extension (to gain fill port clearance when using a moderator) all add weight. A .22 Dreamtact compact, has external reg, hammer and TP adjustments, a slightly longer barrel, an air tube that is about 2x larger, but it is slightly heavier than my stock Prod with AR stock and Donnyfl Tanto. Hmm. – Don

  5. Good morning B.B. and blog-mates.

    B.B., forgive me, I’m still on cup #1 of coffee, but I don’t understand your hold comment. Do you use 2 sand bags and slid the forearm bag closer to your right hand? Doesn’t that make the gun extremely muzzle heavy?

    Gunfun1, wouldn’t the rifling just tear out or tear up the o-rings? Perhaps a smoothbore barrel would work better with your idea. Would a machine install the o-rings? I can’t see how it would be cost effective to have a human install 2 tiny o-rings on every pellet.

  6. RG
    Read my comment to Decksniper about trying them with a rifled barrel and smooth bore. But yep it might and more than likely tear up the o-ring. And I believe the smooth bore barrel will be the winner.

    And yes it would be pretty easy for a machine to put the o-rings on. We do all kinds of secondary work with machines now. We actually have a machine that puts a copper band in a groove on a part then gets stamped on then gets the copper band machined for a seal type fit. So yes it could all be done. Cost effective I don’t know. But you know how it goes with those gimmick type pellets anyway. They always tend to cost a bit more.

    The thing is if they are very accurate it could be a way to have a pellet or slug made in the US. And we have another choice of pellet or slug.

    Here could be one that could get the 2 outside diameters turned down a bit then the o-ring grooves put in. Then the o-rings in the grooves. I use these in my Wingshot ll right now.

    • If a smoothbore, it would make sense to me to keep the diabolo shape for stability, so perhaps a diabolo shape with either a single groove swaged into the head or two grooves, one swaged onto the head and one swaged into the rim of the skirt. Then push the o rings onto either end.

      I can see it now. Perhaps the o rings would center the mass of the pellet better in the bore? Would that improve smoothbore accuracy over a rifled and choked bore with an all lead pellet that gets re-swaged by the barrel?

      • RG
        “I can see it now. Perhaps the o rings would center the mass of the pellet better in the bore? Would that improve smoothbore accuracy over a rifled and choked bore with an all lead pellet that gets re-swaged by the barrel?”

        That’s exactly what I want to find out.

      • RG
        Look at these.

        If I had a gun that shot them I would make the outside diameter about 6 or 7 thousandths smaller. Then find the right fit o-rings and put one on the front and one on the back.

        So basically a person could take what’s available and modify it like I just said. The manufacturer could do the same and produce them.

  7. “That way the o-rings would be the only surface that would contact the rifling in the barrel or the smooth bore barrel.”

    That’s already happening with those pellets. How would o-rings of any other material help?

    • MisterAP
      From what I done with my FWB 300s piston is it let’s the o-ring comforn to the cylinder. I had to try different o-rings to get the seal and friction on blow by right. (Alot of blow by with the factory cast iron piston ring). I have a stronger aftermarket spring in it. When I still had the cast iron factory ring in it, it only shot about 50 fps faster with the heavier single spring. But then I played with different fit o-rings and now the FWB 300s is about a 150 fps faster than the cast iron ring with the heavier spring.

      So my idea is to let the o-rings seal the pellet or slug better than what I have seen with the Wingshot slugs I gave the link to above. They actualy fit the bore sloppy but do produce 1 and a half to 2 and a half inch groups out to 50 yards. I want one inch groups or less at 50 yards out of it.

      And I put oil down the transfer port only about twice a year. And the o-ring has been in the FWB 300 for at least 6 or 7 years.(RidgeRunner when did I get the 300’s from you)?

      But that’s my hole idea about it the o-rings on a slug or bullet.

      • GF1,

        Some Teflon that would be soft enough to conform to rhe the rifling like lead should work. I bet your idea would work with enough development. I see them as an extremely high end projectile for target shooting. Cost would not be an issue if they are better than what is available.

        A precision machined multi-material projectile that is extremely accurate would be coveted for matches and may change the sport. What will folks pay to win a match?


  8. B.B.,

    I don’t know how you have your cheek rest set but if you are getting Up On It that might be giving you groups that look like the first and (less so) the second group. It is a great looking cheek rest but coming from less pronounced and moving to a right hand specific Buttstock has done that to me all to often. The other clue is that you appear to have settled into better groups as your testing progressed.

    You need to find more time for that rifle! You and it deserve the quality time together.

    Of course I’m looking forward to your pellet testing with the ASP20.


  9. BB,
    I don’t know what bag you are shooting off of but I am using a Caldwell Tack Driver bag and love it. I like the way it cradles and even grips a rifle. My biggest challenge with this bag is changing the height of the bag. I have been using some 1 1/2” foam pads as spacer blocks. I am sure there is a better solution.

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