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Education / Training What does dieseling mean? – Part 3

What does dieseling mean? – Part 3

by B.B. Pelletier

Part 1
Part 2

Before we begin, a word to those who are having difficulty emailing Pyramyd AIR. They recently changed their email program and the one they use now is more sensitive to blocking spam. Some ISPs (Individual Service Providers – the place where you pay for your internet connection) are known for their spam, and if the Pyramyd email software detects them, it may discard your email without giving you any status. If you can’t get an answer, I recommend you call them at 888-262-4867. They have worked hard to reduce the phone wait time and, while it’s still not perfect, hold times are much shorter.

Well, this three-part posting is turning out to be one of your all-time favorites. It seems we have a great number of spring gun fanciers in the audience.

Intentional dieseling
Let’s look at how a gun can be made to diesel intentionally, starting with the famous Weihrauch HW Barakuda EL54. That was a standard breakbarrel rifle, the HW 35, to be specific, with a tube on the right side to inject a small shot of ether vapor into the compression chamber just before the shot was fired. I covered it in a special post last year, so you can read all about it there if you want to. The point is thst manufacturers recognized the power potential of a detonation and tried to harness it to make airguns shoot faster. Today, we would call the EL54 a firearm, because that is exactly what it is.

You don’t have to be an airgun manufacturer to make a spring gun diesel. Now that you know how it works, you’ve probably figured out it takes just some fuel coming in contact with the superheated, compressed air generated by the piston. Children have known this trick for at least half a century, which is the basis of the Oil-Can Louie story I mentioned in the previous post. However, that story ends with the destruction of the airgun, so please don’t experiment that way.

Deception through dieseling
Gamo sells a .177 breakbarrel spring rifle called the Hunter Extreme, which they claim is capable of generating 1,600 f.p.s. with PBA pellets. When a friend of mine chronographed his, it was shooting just over 1400 f.p.s. Many of you know that I asked for any reader with a Gamo Hunter Extreme to chronograph their rifle and to tell us the numbers. To date, no one has come forward. Gamo used to show a film clip on their website from the Shooting USA TV program that shows a shot chronographed at more than 1600 f.p.s. I tested a PBA pellet in a .177 Condor and it went only 1486 f.p.s., which tells me something might be fishy about Gamo’s claim. However, it is possible to make a pellet go as fast as that televised shot with some trickery.

All it takes is a pellet with a partial drop of a volatile substance like diesel fuel in its hollow base and you will get velocity figures like that. Forget accuracy at that speed, but the velocity will be there. That’s all some people want to see. The gun may not hold up long with that kind of abuse, and I do not recommend that anybody attempt it. As far as I know, this is the only way to get a pellet from a spring-piston airgun going that fast without extra mechanisms, such as an ether injector.

Daisy used the principle, too!
In the late 1960s, Daisy put the caseless cartridge of Jules Van Langenhofen into production in a rifle that ignited the solid propellant using the heat of rapidly compressed air. Theoretically, their gun was a .22 caliber spring-piston rifle that just happened to shoot a caseless .22 as powerful as a conventional long rifle. In practice, the bore was too large for pellets, and any .22 pellet you tried to shoot in it was hopelessly inaccurate as well as being underpowered from all the blowby. Guns that use the VL system are still popping up at airgun shows, where they now command $150-225, depending on condition. The cased presentation models have always gone for more.

How to stop the detonating
Apart from specific Webley and Weihrauch guns that have piston seals made of PTFE, stopping a spring gun from detonating is iffy. Some guns seem to detonate more than others. Cleaning the compression chamber and lubricating with a small amount of the correct lubricants is a surefire way, but it involves disassembly of the powerplant. You can sometimes solve the problem by putting a drop of high-flashpoint silicone oil into the chamber through the transfer port (or the oil hole in the case of a Mendoza). The high-flashpoint oil seems to dilute the other oils and greases to the point that they diesel but no longer detonate. This isn’t a positive solution, but I have seen it work.

Well, that turned out to be a longer answer than I thought it would be. But, now, when the subject of dieseling comes up, we have a place to turn to.

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.

44 thoughts on “What does dieseling mean? – Part 3”

  1. BB,webley & weihrauch piston seals are not made of PTFE,THEY ARE MADE OF POLYPROPYLENE,and a good job to,i have an old HW80 witch i run with a t.r.robb piston seal made of PTFE, the problem with this is when it gets cold the washer shrinks, its good in a hot climate, you should only lubricate the washer with one drop of silicone oil, around the seals rim,and this would last for meney thousands of rounds,you cannot lube your spring or chamber in the normal way because the oil will get in front of the seal, with almost every shot your gun will be diesiling,you do get more power out of your gun with theas seals but ther are no were near consistant,as delring or polypropylene thats why they dont use them

  2. This if off subject, but I wanted your opinion on whether I should get a Gamo Shadow 1000 or a winchester 1000b. Which do you think would be better? Thanks in advance

  3. B.B.

    Sorry to be so vague. Which would you recommend?. I understand for the money these are not top notch air rifles. I have a 800x and have been very happy for the most part. I know you have done an article on the Gamo 1000. I did’t know if you had shot any of the winchesters 1000x or 1000b. Supposedly the 1000b has some improvements over the 1000x.

    Thanks in advance.

  4. BB,whats the gamo hunter extremes accuracy like,even at 1400 fps thats alote of power for a .177,i have seen the video with the pig being shot, but could ther be any real application in the wourld of hunting for this gun when i say about the accuracy i mean out to 50 yards what sort of groups would you exspect to get,could you get all of the pellets inside a 2 inch circle? or are we talking about pigs heads at 10 yards!

  5. B.B. one last question. Which air rifle would you recommend for the $150-200 price range for target shooting and small varmit hunting?

    Thanks in advance

  6. well, it seems like some ppl have luck with the extreme, when others don’t…on the cabelas website, they allow you to write reviews on products, and one person stands out in my mind saying that they got inch groupings with pba ammo in the extreme at 65 yrds…whether or not they are telling the truth, i know not, but there are other reports of people having a very accurate extreme. however, if a normal pellet does happen to go that much above the speed of sound, you can expect 3 inch groupings at 10 yards or worse!! i can tell you right now that bb doesnt like the pba ammo, and i feel the same way…completely false advertising, and you don’t get the penetration that is promised.


  7. bb,

    i have read a lot of reviews about the winchester 1000B, and a lot of people say they own a shadow and winchester, and the winchester has more power(and more sound)…i haven’t tested one, so i can’t tell you for sure…but i do have a ?…a lot of people say their stocks shattered after a few hundred shots, and i just wanted to know if that is a result of loosened screws or not, because i am looking into buying one, but i want to know everything about it first. thanks bb.


  8. Nathan,

    I think the Gamo Hunter Extreme is probably a pretty nice air rifle. The Hunter 1250 certainly was, and the Hunter Extreme is based on the 1250, I believe.

    But it’s very difficult to shoot tight groups at 50 yards with a spring rifle. And a breakbarrel is the hardest of all. A BAM B40 would be a much easier rifle to shoot good groups at 50 yards and still have good hunting accuracy, and a TX200 would be best of all.

    For under $200, I recommend the Gamo CF-X.


  9. Hi BB,
    This doesnt have to do with dieseling, but I dont know where to ask a question in general when I have one. So I’m asking you here.

    It is said that ANY gun cannot shoot any faster than the speed of sound in the propellent that the gun uses (under whatever conditions prevail). I can see that some airguns can indeed shoot 1400+ fps which is certainly faster than speed of sound in air (forget the accuracy right now).

    Wanted to know your thoughts on this. Also, since I’m interested in internal ballistics, is there any written work on this aspect of airguns ? I am looking for a good physics description / analysis coz thats the only way I understand it well.

  10. Dave,

    I don’t believe the report on the Cabelas site. I once knew a man who claimed to shoot a Crosman 760 at tin cans at a distance of a quarter-mile. Claimed he hit them all the time.

    At 65 yards I believe any good shooter shooting a Hunter Extreme would be hard-pressed to keep a five-shot group under three inches. That’s with GOOD pellets. With PBAs I don’t think they could stay under 12 inches.

    I read all the reviews and they do range from good to bad, though they all gave the rifle high marks for its appearance. One guy even thought that the Extreme is the most powerful airgun ever! Boy, is there a whole universe of more powerful airguns waiting for HIM!

    Most reviewers thought the PBA was inaccurate, but a few said it was very accurate at long range.

    The Gamo rifle are accurate, but not moreso than Weihrauchs or Air Arms.

    It’s time for a thorough test!


  11. MajorKonig,

    There have been several explanations of how an air rifle can exceed the speed of sound on this blog, but they are buried in the comments and I don’t know where they are.

    It is certainly possible to exceed the speed of sound with a pellet rifle. I do it regularly.

    I’m not to right person to write the explanation, so if any reader can do so, I’m asking you to do it here.


  12. If I may offer an opinion of the Daisy vs. the Gamo….

    The Daisy is a more powerful gun, it can easily shoot 50-100fps more than a Shadow. It tends to be quite accurate as well, in my hands it wasn’t much (if any) worse than my Shadow.

    However, the gun is much, much less pleasant to shoot. It’s loud, it kicks, it is much harder to cock, and it has something of a reputation for mediocre durability. Shoot the Daisy for twenty minutes, and switching to the Gamo feels like a “vacation”.

    The trigger and weight balance on the Gamo are superior, as is the overall workmanship. The Shadow had a lifetime warranty, the Daisy didn’t.

    If you have to get internal parts for the Daisy (springs, seals) – forget it. Gamo does have some limited parts support, and there is some aftermarket support for it as well. Break the Daisy out of warranty, and you’re stuck with paying for factory service parts and labor.

    The Daisy beats the Shadow over the chrony, but that’s about it.

  13. i bought a hatsan mod. 60 .22 cal rifle for my son here in canada it is under the 500fps limit for non f.a.c. shooters but it hits very hard has very good accuracy and is very well built. i believe these winchesters are being made by them. in canada this rifle retails for $170-$200 which i think is preety good value for the money.

  14. I often put an oil drop into pellet,especially when I want to surprise someone 🙂 I’m using Gamo shadow 1000, with homemade gas ram powerplant. usually without diesel, it shoots 880fps.
    with diesel – 1130fps.
    Ok, I trust my gas ram strenght, seal replacement is not a problem at all, so what else can I break by shooting like this?
    Thank You.

  15. Oil Can Louie’s gun blew apart. The barrel came off the gun.

    You could also enlarge the compression cylinder, which is the frame of the gun. If that happens – no more airgun.

    Finally, parts can fly off the airgun at speeds high enough to injure you or bystanders. In the 1960s I told a man that he should stop firing his damascus twist shotgun altogether. It was only proofed for black powder and after nearly a century, it probably had major internal rust – hidden from view. I didn’t make this up – it was a warning repeated in every gun magazine of the day.

    But I was a teenager and he was an adult, so just to show me there was no danger, he put a high base shotgun shell in the gun and – blew it up in front of me. The parts flew like schrapnel from a hand grenade!

    I can only warn.


  16. seems like i need to express the same sentiment here, that i used when answering a “double pellet loader”…..”just because you can do something, doesn’t mean you should do it”….and in the famous words of Blue Collar comedian Ron White, “LOOKS fade with time, but STUPID is forever”…

  17. B.B.-


    ISP=Internet Service Provider, not Individual…

    Also, I’m really curious about the Diana 460. Why does the Diana site claim several hundred fps less than everyone selling it (720 vs 1150)? So I’m really curious what it will really do. When you test one, would you please do the .22?


  18. i think diana is one of a few companies that use higher weight pellets to test their guns. these figures on their web which i have also been on many times i believe reflect realistic velocities for most gun in this range.

    up here in canada ah!

  19. hello B.B.,

    i just finished reading all 3 parts to your review on the rws 54. when you get a chance to review the rws 460 magnum, please be as detailed as the rws 54. i will be trying to determine which of these two to plop my $500 down on once I have sufficient info. i am also hoping you will be testing this in .22 . thanks.

  20. i find the velocities on diana’s website to be really confusing. in the pdf manual for the model 54 in .22 they have 230m/s = 900fps, and on the detail page its 760fps. for the 460 magnum its 235m/s = 780fps in the pdf manual, but 720fps on the detail page. confusing to say the least

  21. Can I shoot Gamos round lead balls out of my Shadow 1000?

    I got a sampler pack and it had a tin of those in it.
    I don’t want to waste them but I don’t want to risk them damaging the gun.
    I’m concerned most about blow-by.

    If they can be used, would they be accurate?

  22. b.b.,

    last few questions have been about rws guns, which got me thinking. i’m trying to decide between the rws350 magnum, and the 52/54 models. i’ve read ur previous posts and comments, and the one thing i know is that “i don’t want to lose any fingers”. what do i mean? i noticed your reviews about the rws52, and if a person wasn’t careful loading the chamber, their fingers could be cut off. does someone have to do something completely idiotic for this to happen, or do the safety mechanisms in place make this idiot proof and an impossibility that could never happen. if it is a possibility, what do i want to make sure “i do not do”?. thanks in advance.

    p.s.- does the recoiless feature of the 54 really work, and is it worth the extra money, meaning, would i enjoy the 52 just as well with proper technique and the money left in my pocket.

  23. B.B

    Have you ever noticed when shooting a springer that a certain pellet makes the gun shoot a lot more quieter and smoother?

    I noticed this before when I was shooting a s1k off a make shift bench into the woods at a target at 30 yards. I was using Gamo pro magnums and clover leafing if I did my part.

    Do you know what causes this? Is it just a good fit and weight for that particular gun?

    I have also noticed that my newer Gamo s1k has a very tight barrel. I haven’t had much time to test it. It still has under 100 shots put through it and it still has stock sights.

  24. Beartrap,

    You can lose finger with the 350 Magnum just as fast as with the sidelevers. But the Diana sidelevers have the mmost positive safety system in all the airgun world. I think it’s even better than the TX200’s, which is also great.

    Diana sidelevers are very safe if you don’t do anything foolish.


  25. CyberSkin,

    Yes, I’ve noticed the “smooth operation” phenomenon.

    With some pellets it seems best, but with others that are also smooth, the accuracy doesn’t seem to be there. I do think the powerplant is suited to certain pellets, but accuracy is a category of its own.


  26. hello again bb,

    you missed two parts of my previous question:

    “what do i want to make sure i do not do [when handling the rws 350 or the 52/54 models]”


    “does the recoiless feature of the 54 really work, and is it worth the extra money, meaning, would i enjoy the 52 just as well with proper technique and the money left in my pocket”

    Thanks again

  27. B.B.,

    are crosman premiers the only “lead” pellets made with the alloy that leads barrels at high speeds? the reason why i ask this is Gamo tomahawks look like a peculiar lead also…


  28. 350/48,

    Don’t put your fingers into the mechanism to load without restraining the cocking lever or barrel.

    Yes the recoilless system works. So well, in fact, that the 54 is smoother than my Whiscombe. It is well worth the extra money, in my opinion.


  29. Bb,
    I am a rookie in this field. Just started shooting a week ago. My pistol is a cheap indian made break barrel. I bought it for a start. Right from the beginning smoke comes after every shot. First i thought it was nice. But after reading ur post i am disturbed. Is there a need to stop this dieseling? How can i stop this?

  30. Hey BB,

    I just purchased another Hatsan for my collection, a Model 95 Vortex .22. It dieseled pretty bad the first few shots, it was louder than a 22LR. After about 3 shots the loud noise started to subside with every shot. I’ve put about 30-40 pellets through it and its still getting quieter but a substantial amount of smoke shoots out of the barrel with every shot. I’m wondering what your experience has been with new rifles and the amount of time it takes for the factory oils to burn off? This is my 11th spring/gas ram gun and none of my other ones have taken this long to burn off the oils. I’m worried that all the dieseling is going to damage/lower the performance of my Mod 95 Vortex. Thanks!

    • Mitch,

      All spring guns diesel. Your will continue as long as it lasts.

      The problem is detonation, which are the explosive shots. When that goes away, everything is fine.

      I have guns made in the late 1960s that smoke on every shot. It’s normal.

      Some guns do and others don’t. But it’s not harmful to the gun.


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