Changeable air transfer ports

by B.B. Pelletier

This subject was raised by Frank B., I believe, from our conversations regarding deep-seating pellets in spring guns. Someone asked if the transfer port of the Hy Score 801 was particularly short, which he felt explained why seating pellets deeply would show a velocity increase.

I have to tell you that it isn’t that simple. The air transfer port conducts the high-pressure air from the compression chamber to the back of the pellet sitting in the breech. While it has a simple job to do, the transfer port is another factor in the overall performance of the gun. In that capacity, the tune of the gun relates directly to the length and shape of the transfer port. Yes, I said the shape, too.

If you have a .22 caliber Beeman R1 humming along at 22 foot-pounds and you alter the size and shape of the transfer port, don’t count on the gun delivering the same power afterward. In my experience, and from what limited testing I did with the set of ports I’m about to show you, the power usually drops when the port is altered.

Changing port dimensions and shapes was all the rage back in the mid-1990s. Jim Maccari did a brisk business altering ports for customers. And he came up with some observations of his own while doing it. If you want the rifle to continue to function over a broad range of power, based on changing the state of tune (without altering the transfer port), he found it was best to leave the port as the factory designed it. Let me give you an example to illustrate the wisdom of that.

The Beeman R1 used to come in all four calibers (.177, .20, .22 and .25). But when Weihrauch produced the R1, they made the transfer port the same size for all of them. It would have been a costly management nightmare to make a spring rifle in different port sizes according to the caliber. So, all R1s came (and still come, I believe) with a transfer port that’s very close to 0.125″ in diameter. The actual size is metric, but that’s what it measures on an inch scale.

Now, say you’re the owner of a .177 R1 that you want to rebarrel to .22. All that’s needed is a new barrel and cocking link. Everything else on the rifle is the same between the two calibers. But if you altered the port for enhanced performance in .22 caliber, you might find it next to impossible to get decent performance out of it in .177. And, when you altered the port for optimum performance in .22, that’s just for one or two pellets. You generally lose performance with other pellets when you make changes.

Because the transfer port is such a permanent part of the spring tube, any changes that are made can be permanent. Yes, I know of several ways to bush the spring tube so you can start all over, but is it worth the effort? Jim Maccari apparently didn’t think so, because he donated a ruined spring tube to me for an experiment. Dennis Quackenbush made a set of transfer ports that slid into the hole and were held in place with a setscrew.


The transfer ports were inserts held by a setscrew.


Dennis Quackenbush made these transfer ports in graduated sizes. He gave me several blanks for further experimentation.

Another thing to think about is the shape of the transfer port. Many people suggested an air venturi. That would be a smaller hole with a bevel on either side. A properly designed venturi should speed up the flow of compressed air because it’s made to pass through a tunnel that changes shape from large to small. But I never recorded any advantage from a venturi-shaped transfer port, perhaps because the machining was too rough.


A venturi shape was tried but gave no conclusive results.

Before you start your drill press, please know that I was never able to get this setup to shoot as well as an unaltered R1, but it was good enough for a few experiments. In a nutshell, here’s what I learned:

1. Transfer port sizes from 0.120″ to 0.145″ give the same results for a .22 caliber R1 tuned for maximum power…in this gun, which was about 19 foot-pounds. When the size drops below 0.120″, the velocity slows. When it gets above 0.145″, it slows and the gun acts like it’s being dry-fired. Lotsa dieseling, etc.

2. Exotic shapes such as venturis don’t seem to affect the performance within the optimum size range and the targeted caliber.

There’s more to the study of transfer ports, like ports that are centered in the compression chamber, versus ports that are offset to one side. But this should get you thinking.

158 thoughts on “Changeable air transfer ports



  1. Dave,

    The easiest way to reduce power is by making the swept volume of the compression chamber smaller. Another way is to reduce the transfer port size.

    What does not work is adding a weaker mainspring. It may reduce the power somewhat, but seldom does it go as far as needed when the base gun develops 15-20 foot-pounds. Then, too, the customer could always replace the spring, making the gun illegal. The Home Office might then make that model illegal to import as a legal limit gun.

    B.B.



  2. The subject of transfer ports in springers is a complex and fascinating one. For a more in depth look see B.B.'s excellent 3-part series:
    http://www.pyramydair.com/blog/2008/11/air-transfer-port-part-3.html

    One thing that may have escaped sufficient study in the matter of the transfer of potential energy from the compressed air to the pellet is turbulence. One of my roommates in college (oh so many years ago!), a Japanese physics wunderkind, wrote his Masters thesis on the dynamics of turbulence in flows. The only thing I remember of our discussions was a comment he made that the study of turbulence was so complex that certain aspects of it were still unsolved by modern science. In some of his experiments he induced turbulence by forcing gases and liquids to travel from one chamber to another via various differently-shaped passages (transfer ports.) He colored these materials with dies and photographed them at very high speed under different wavelengths of light. No doubt a study of the performance characteristics of different sizes/shapes of transfer ports in airguns vis-à-vis turbulence as an energy thief would've been a fascinating one to him. Perhaps some bright young physics major will pick this up where he left off.

    -AlanL


  3. AlanL,

    Maybe turbulence in a trasfer port hasn't been sufficiently studied. Maccarri worked on this issue ad naseum and even took an R1 and made it centrally ported to partly understand turbulence. He tested many different port shapes for efficiency including the venturi design that B.B. mentions and a stepped design that worked best "with certain tunes".

    In the cardew book from trigger to muzzle the issue was tested extensively as well. Since their testing was done back in the 70's when springers weren't going as fast this info, while interesting, is less relevant today in my opinion.

    My hats off to "a young physics major" that could create something that hasn't already been tested.

    kevin


  4. B.B.,

    Perhaps the testing you're summarizing was this finite but in paragraph 6 you say,

    "And, when you altered the port for optimum performance in .22, that's just for one or two pellets. You generally lose performance with other pellets when you make changes."

    Did you mean "pellets" or "calibers"?

    Maybe the testing was so detailed that optimum performance of specific pellets was measured.

    kevin


  5. CJr,

    Excellent start to todays topic. I'm glad I didn't spill my coffee.

    We haven't heard from Jane Hanson or Herb in quite awhile. I for one would like to hear their comments on AlanL's post.

    Mr B.


  6. Transfer ports – can’t say I can add much to that. Most I’ve done is open the breech side of a .25 cal BSA with a cone shape, but that was only because the pellets did not fit.

    However, it did get me started on the idea of an actually personal transfer once the kids are out of school. Seems Forbes has picked Pyramid Airs home town of Cleveland as the most miserable city in the whole country. I took some comfort in the fact that I live south, closer to the Canton area, which is only 9 out of ten.

    Derrick – not sure how Akron or Y-town dodged those pellets?

    http://realestate.msn.com/slideshow.aspx?cp-documentid=23468266#2

    Update on the .20 caliber R-1. Beeman Lasers hit the target like I am blind folded, but Kodiaks show some promise. Once I find the best pellet I will pit it against the $75.00 Gamo at 15 yards and publish the results.

    Kevin – you still have a pell-seat coming, but it will be a new one. I can only find my original and the two of us are pretty close.

    Volvo



  7. It sounds like gun makers figure it out and make it right to begin with.

    Altering the transfer port doesn't seem to improve things.

    The gun with a pellet seater worked best with it and most other airguns seem to work best with flush seated pellets.

    David Enoch



  8. Volvo,

    My mothers side of the family has deep roots in Michigan and Ohio. We bury her people in Waseon, Ohio and have to fly into Toledo for that grim ritual.

    Nice people. Lots of Quakers in that side of the family. Interesting people I'm related to.

    Don't care much for the climate back there though.

    You're very kind to send a brand new pell-seat. I want to assure you it will be put to good use. Thank you.

    kevin



  9. Most visitors to this blog are familiar with Paul Capello's excellent series of video reviews for dreamy air rifles. Those that aren't should acquaint themselves:

    http://www.pyramydair.com/video/

    He also is co-host with the dashing and charming Tom Gaylord on American Airgunner.

    What I did not know was that Paul made custom computer cases. He was featured on an episode of "The Screen Savers" on techtv, which I believe is the forerunner of today's G4 cable network. You can check out his work on YouTube by searching his userID pacapello. I was particularly impressed with his Doom-themed case:

    http://www.youtube.com/watch?v=a89yRqqK1T8&feature=channel

    He also did a video review of the RWS 850 airmagnum before he became affiliated with PA. It is a good review and fun to watch because Paul is so surly in it!

    http://www.youtube.com/watch?v=p8ORFVY4yHg&feature=related

    http://www.youtube.com/watch?v=HX6gVvZzMsc&NR=1

    Mr. Ungier certainly has a knack for drawing top talent.

    WV: skymal. Maybe Josh should advertise with the airlines.


  10. b.b., so out of interest. I have the 'Canadian' Slavia 630 (495fps). You mention that they reduce the power through reducing the swept area of the compression chamber.
    Now not that I would do this ;-), the 630 is such a sweet shooter, but the extra 100fps in the European model would sure be nice.
    Is there a way to inexpensively to raise the power?
    CowBoyStar Dad



  11. CSD,

    Changing the stroke in a springer is a major operation. It's relatively easy to alter the notch on the piston that catches the sear, but then you also have to change the cocking geometry, so the piston goes back far enough to catch the sear.

    A cheap approach? Shave off a little of the piston seal or crown.

    B.B.


  12. Anonymous Marauder Guy,

    I got one in .177 from the other side of the world before Crosman or PA offered them. It works as designed, and is especially good for oversized or soft pellets. Bottom line is that one pellet in it is a lot more than one tenth of the effort of loading ten pellets into the magazine.


  13. Slinging Lead,

    Thanks for the links. I think Paul ran out of coffee that day as well as pellets.

    I'm constantly amazed at the mods people do to the 850. Have you seen the mods and custom stocks that roald sells?

    kevin


  14. B.B.,

    pellets vs calibers

    OK, that makes sense. Thanks for your patience. Please remember I rode the special short school bus to school and had to wear a football helmet even though I didn't make the team.

    kevin


  15. Randy-in-VA,

    Does the marauders magazine function well with large pellets like kodiaks and quirky loading pellets like predators or is the single shot tray the only way to load these "unusual" pellets in a marauder?

    kevin


  16. Hi,
    I have a $500 budget and am looking for an air rifle mainly for target shooting, plinking and would possibly like to get involved in some field target or silhouette competitions. I don't plan to hunt with it. I would like to be able to shoot accurately out to at least 50 yards and beyond if possible. Can you give me your recommendations for a rifle that will fit the bill in this price range. I have been researching a lot of different guns and really enjoy your blog so your opinion is really appreciated.
    Thanks,
    Mike


  17. Kevin,

    In the .177 magazine, I have not found any pellets that do not fit, and that includes Predators and Eun Jins. In the .22, I've seen where the clear front face has had a circular groove milled into it to accept longer pellets like Predators. I have also read of shooters snipping off part of the red tip.

    The compression from the spring tension of the magazine distorts softer, all-lead pellets. Most of the Crosman pellets have antimony in them to make them harder.


  18. B.B.

    It never occurred to me that you could alter the transfer port. Taking a look at the overall transfer of energy as opposed to a detailed look at the forces, I would say that there probably is not a lot one could do to enhance performance. The energy that goes in one end has got to come out the other end. Certainly altering the port could affect the tune and vice-versa, but I suspect this is a matter of juggling variables to get essentially the same result.

    The most important factor of diameter could clearly have an effect outside of optimum boundaries which you seem to have discovered by experiment.

    Invoking the law of entropy, I suspect that one could do a lot to decrease or disperse the forces coming out of the transfer port. The example that comes to mind is the new Vortex muzzle brake from Smith Enterprises Institute, one of the premier operations for refurbishing M1A's. This muzzle brake has something like an internal spiral groove that is so effective that the muzzle report of a .308 is greatly reduced and the flash is almost invisible at night.

    So, if one can dissipate energy transfer like this through a tube, could one boost it as well? I don't believe so because of the irreversible nature of entropy. The last time we had this discussion (when Jane revealed her rocket science background), I think she recommended having a cylindrical tube (which we already have) and polishing the sides the way they do for rocket engines.

    Matt61


  19. Mike,

    Accuracy seems to be your primary concern, so I would recommend a PCP such as the marauder. You'll need a bit more to get set up with a pump and or tanks, but it will work out to 50 yards for you. Some springers are accurate to that range, but they generally require a tune and lots of technique to do so. I'm not sure that they'll still be within budget. Of course, we haven't even begun to consider the scope necessary to shoot an airgun with precision at that range, but it's going to cost a good bit also.

    A Benjamin Discovery might be the best option as you could get it, a pump, plus some decent glass for right at $500. Of course, they're pretty lightweight, so accuracy will be more difficult than it would be with a Marauder. Still, that might just be one more reason to practice more :-)

    Hmm, your budget might be on the lean side for this kind of long-range shooting. Now, if you were willing to limit yourself to 30 yards or so, then there are any number of guns that might fit the bill.



  20. Matt,

    The best that you could hope for in the transfer port would be to minimize losses from friction and turbulence, and even then that would impact that mystical balance that governs the spring launching the pellet.




  21. Mike $500,

    I'm a newbie myself. But here's my 2 cents for what it's worth:

    A spring piston rifle is less hassle than a precharged pneumatic (pcp) but harder to shoot accurately. I.e. more challenging, more fun? ;-) It is also single shot, whereas with pcp you can get a semiauto for up to 10 shots.

    Consider the RWS Diana 34, a good quality and powerful springer that will get your pellet out 50 yards on a reasonably flat trajectory, in either caliber. It is accurate when properly sighted in. This rifle is only about $210 which leaves you enough to get the proper UTG mount and a nice scope for it, with enough left over for pellets. Keep in mind that for Field Target you have to shoot .177 cal.

    -AlanL


  22. Mike,

    If you are open to a PCP, I think the Benjamin Discovery would be ideal for you. If field target is a possibility, you definitely want to get it in .177. And get the package deal with the pump.

    I woul;d hold off on buying a scope until you've learned how the rifle operates. You'll still have great accuracy with open sights if you are careful.

    B.B.


  23. pardon the noobie question, but does this mean the the modification to round off the exit port in the valve in the 1377 is a waste of time. I bought a spare valve to change to flat-top and was going to smooth out the angle, but won't if it doesn't make a difference.


  24. BB, i'm the one asking questions about the 397, but a problem has arose. I'm only 15 and my mother doesn't like the lead pellets due to health reasons. Are there any good lead free pellets that don't have insane velocities?

    Thanks, HK


  25. jz2,

    The 1377 is different since the air path from the exhaust valve to the barrel is a 90 degree turn with a sharp edge. Some folks have smoothed the angle in the exhaust valve body. The gun will pick up some velocity, around 15-20 fps, I think. If you do some searching you can probably find a writeup.

    Paul


  26. Hello Paul
    I found an extensive write-up by "airpit" called 13xxHotRod and was going to implement the changes the author outlined. one of the changes is softening the 90 degree angle. I'm going ahead with the mods.
    In a related question, other than weight, is there any difference between the newer aluminum valve and the older brass valve body?
    thanks… by the way let me join the chorus of praise for B.B. and the others who contribute to this blog.


  27. HK,

    There are heavy "lead free pellets" that won't give you insane velocities.

    I've tried two types in several guns and gave them away because accuracy was terrible.

    I have two suggestions for you.

    First, google "lead free pellets" and try them in your gun (397?). Maybe they'll be accurate enough.

    Second, after you've RESPONSIBLY shot your airgun maybe your mother will be more willing to listen to your arguments for lead pellets. There is a lot of good information on this site about lead pellets not being harmful if shot into a pellet trap. Ingesting lead is bad so don't eat the pellets and lead dust can be harmful especially to small children. Use the box on the right to search and get more facts from the web (google?) to bolster your case to Mom if the lead free pellets don't work well in your gun.

    kevin



  28. Marauder single shot tray,

    Well it works if your fingers are small or your good at rolling the pellet down… (some pellets roll straight slightly better…)
    get the idea…

    NO, it's not great to use, but one can learn to do it ok..

    The single shot tray on the Air Arms S410 is even narrower, and so harder.

    What most Field Target match directors usually allow, is to simply take out the mag and put it back in again.

    When you cock the rifle, you can then remove the mag, check it's fill level, and replace it and shoot. The idea is that a magazine gives one more time to find and sight in on the target.. so removing and replacing it also removes the advantage. So forget the single shot tray..

    But if that's not what fits your world, I have 2 to sell for either gun.

    Wacky Wayne,
    Match Director, Ashland Air Rifle Range


  29. Under $500 but, accuracy to 50 yards gun guy..

    HMMM
    Well, again we need more info.. If you mean total outfit under $500, then I too say Discovery… and if that's gun only, then used Air Arms S400 or new Marauder.

    But… When I saw the words "field target" and "under $500" in the same paragraph… I laughed..

    Turn back if that is truly your long range budget for the game..

    But race forward with the Discovery, leapers 6-24×56 side focus AO scope, and pump, (cause the guys at the range will fill your 2,000 disco with their wasted air under 2,800), while they show you the ropes…. and spend your money for you:-).. and one of them will have a used cheap tank to sell and knowledge of best place to fill. .. The pump is great as a back up, since the gun is so easy to pump to fill.. and when you don't want to bring a tank. Also, when the guys see you pumping, they will feel sorry for you, and make friends quicker.. offering you their air.

    It's all the best of fun, you'll want to do nothing else.. and seeing and shooting the other guys & gals guns, is the best way to see what you like, in way less time, and way less money.. and who knows..

    ..you could just kick ass with the disco outfit.. and never spend another dime. It's possible..very possible! .. but at least you'll be in the game!

    Wacky Wayne, MD. Ashland Air Rifle Range


  30. For those of you who have commented on my opening comment on today's blog: SL, Mr B, and someone else (I couldn't find the third commenter again, Fred?), thanks for the acknowledgment. I should include BB in this comment as well because without him my comment wouldn't have materialized. Had it not been for this blog and BB I never would have known there was such a thing as a Storm. So this old sailor did learn something. And because of this blog I have so much more material to fuel my feeble comedic attempts. My dad, god rest his soul, was a master at corny humor and I think I may have inherited a nucleotide of that gene molecule. However, no matter how hard I try I don't think I'll ever be able to elicit as many or as loud groans from my audience as he did.

    -Chuck


  31. B.B.,

    Picked up my Benjamin 392 a couple of days ago and discovered that the air left in the gun had leaked out. She wouldn't compress air, gave her a healthy shot or two of Crosman PellGun oil, felt the pressure build up and she seemed to be shooting ok. However, she will not hold a pump or two more than an hour or so. What should I try next? Thank you!

    Mr B.


  32. HK,

    Well, you have to do what mom says, so I would look at the Skenco line. They have synthetic skirts and zinc cores.

    Try this one:

    http://www.pyramydair.com/cgi-bin/zoomed_model.pl?model_id=368&type=P

    and this one:

    http://www.pyramydair.com/s/p/Hyper_Velocity_Lead_Free_Field_Pellets_Type_3_Long_Range_177_Cal_8_5

    If mom would go for a plated pellet that has no lead exposed, this one would be great in your gun:

    http://www.pyramydair.com/s/p/Beeman_Kodiak_Double_Gold_177_Cal_10_65_Grains_Domed_250ct/616

    As long as you shoot into a quiet pellet trap, no lead would ever be exposed.

    B.B.


  33. Mr. B.,

    Your intake vale either has a small piece of dirt on the seal or there is a small cut. Your rifle probably needs a rebuild.

    However, if you shoot about 50 shots through it there is a chance that the dirt will be blown off the seal. Try that.

    B.B.


  34. If I were not going to hunt, yet buy one airgun for targets, plinking and FT…I would probably check out a .177 Marauder, but $500 may not leave much for a pump or air tanks and a scope. For me, I like to hunt, so a .22 is a nice middle of the road cal. that I like. Also, it can be ran on CO2.

    AA Tx200 mkIII has a good rep along with HW97 and rws 48, 52 and 54 for springers. In FT .177 seems to have a little edge.

    Lately, I've touched up a Daisy 1894 plastic stock model with a safety. I like the fact that the hammer and loading port actually work and not just for looks. I added a saddle ring and a few drops of pellgun oil and spent some time shooting cans in the basement.

    The Daisy BB gun is for a friend of mine who had a similiar one one he was a kid. He got his first BB gun (daisy 1894) when he was 9 in 1963 and shot it until it wore out 21 years later.


  35. Kevin,

    Re: Marauder magazine – I have a .22 Marauder and the Predator Polymags and the Eun Jins will not fit in the magazine (too long). I got my brother, a retired machinist, to modify 1 of my 3 mags in the way Randy-in-Va mentioned. The circular groove is cut to half the depth of the thickness of the clear plate. This altered mag will readily load the Predators but the Eun Jins are still too long, and I didn't want to remove any more material off the clear plate for fear of breaking. To shoot the Eun Jins I have to use the single shot tray.

    Which, I might add is usefull in this type of situation. It is about as hard to load as Wayne mentioned, but if you don't want or have the means to alter the magazines they are usefull (although overpriced; hey its a piece of plastic and one o-ring!!).

    I was very glad I could use the Predators in the altered mag cause' my M-rod loves them! My best hunting shot with it was a squirrel at a measured 75 yards. I can't wait for the weather to get better.

    David H.


  36. I think we really beat-up transfer ports in the last series. To me, they are still a massive compromise. On the one hand, they benefit by being small and restrictive enough to allow the spring to put all of its energy into the air, (before the pellet leaves); and on the other hand they benefit from being large an non-restrictive, to then quickly transfer that energy behind them into to the pellet in front.

    They are rocket nozzles with a different purpose, (we tune our nozzels to create, in effect, "maximum recoil") and I can see the use of nozzle science principles to help the manufacturers optimize their guns.

    One thing that was mentioned was turbulence. We briefly discussed this before. We use "Reynold's numbers" to quantify turbulence and differentiate between turbulent flow and laminar flow.

    Turbulence is good for carburetors, (to mix gas in air), but bad for nozzles and transfer ports – turbulence essentially wastes energy, and that's the last thing we want to do.

    We discussed earlier that we can optimize our ports, (without mucking up the original design), by smoothing and polishing any curves and surfaces – this will decrease turbulence.

    Try as I may, I can not imagine what benefit a venturi would give. Sure it increases velocity in the center, but the velocity then slows upon exit – the air exits no faster than it enters! (carburetors use venturis to create a low-pressure zone to draw in gasoline).

    We also discussed particle concepts and column velocity, that explain why each diameter pellet will have an optimum diameter transfer port.

    To me, transfer ports are one of the most thought-provoking parts of the air rifle….I think about them all the time.

    regards,

    Jane



  37. I order a .22 cal barrel directly from Beeman some years ago; it was around $160.00 I think. You could also post on the yellow classified for a trade or to just sell your .177 barrel to recoup some cost.


  38. Jane,

    Thanks for the clear and concise recap of the transfer port subject.

    How did the Evanix Blizzard work out for long range pest control?

    I'm kind of sorry I sold mine, I wanted to test it and she was so accurate and powerful and fairly quiet… but, I don't need it, didn't need it, with the open space hunting conditions around here… but I miss her terribly!

    Just wondering if yours had a similar effect on you?

    Wacky Wayne, Match Director, Ashland Air Rifle Range


  39. Jane H,How would you percieve a transfer port that imparted spin to organize the rapid exit into a column in the barrel….do you think it would help the transition? Sometimes I think that facilitating the pressure transfer may just yeild consistent pellet velocity,rather than signifigant velocity increase….anyway,I am very glad you are still around!Your perspective is so helpful…


  40. jz2,
    13XX HotRod did not google well; got a link?

    BB,
    I'm on the Dianawerks forum and have RWS 46's and a 450. The 46's have a looong transfer port so are inefficient and the 460 has a short, straight one. Others on the forum have the perception that the transfer port on the 460 is shorter/more centered than other RWS guns. Is that true? I thought the breakbarrels were just as short and straight(I'm hearing the port on them may be angled up)???


  41. B.B.

    In Paul Capello's video report on H&N pellets he explains one of the specs. on the tin cover as "average energy in joules". I understand muzzle energy as it relates to a pellets weight & velocity and that joules is a different unit of measure for that energy (we're more familiar with ft/lbs.), I'm just trying to understand how H&N derives at this number. Anyone else who may know please chime in. Thanks.

    David H.


  42. BB,how rude of me….Thank You for this topic.It is a great one to worry over in my head.When I get the room to work effectively,I'm afraid I am going to have to tinker…too many ideas I want to explore!Now don't get me wrong…I have learned that not many stones remain unturned….and I certainly don't expect to discover the earth is flat!But it should be rewarding to try some things anyway.For this I thank you….Frank


  43. BB–love your work, BUT…and I do want to rush you. When are you going to review the Benjamin Trail Nitro Piston rifles? Dying to buy one, but I want your word/review on it first.

    THANKS!
    rob





  44. David H.,

    Thanks for the .22 caliber marauder magazine details.

    If I had a brother that was a retired machinest, and he lived closeby, that would be enough reason for me to get into airguns.

    Lucky you.

    kevin


  45. It looks to me like the transfer ports must be about optimum in size….considering the velocity race. The manufacturers would change them if it would make much difference…then add a couple hundred more fps on top of that to make it sound even better.

    twotalon


  46. Hi BB,

    Thanks for the interesting topic! My $.02…

    Ports on race engines are enlarged and polished to improve airflow. I remember reading tests done that said the biggest improvement came from polishing to rid the port of as much turbulence as possible (turbulence causes restriction and wastes energy, as Jane said), as opposed to just enlarging it. Runner length also matters for the performance on a IC engine (think of the inertia of the moving air), but beyond friction losses and volume, I don't think it matters much on an airgun. Shorter should be better by a small percentage.

    From this, I would think that the best thing you could do for your port would be to polish the existing port and round off the corners in the passage, not necessarily enlarge it much. Manufacturers may not want to take the time to polish (since polishing takes time and time is money), for the small reward of a few extra fps.

    Every little thing you do to an airgun, from polishing ports to crowning and trigger work improves it (providing the improvement is done correctly). My TF99 is testament to that. I took a marginal gun and made it into something that I am now hesitant to sell, even though my friend wants it. But he's a good guy, so I'll probably give in….

    /Dave





  47. Rob,

    I have been sick for the past three days, so I've barely been able to keep up with the blog and comments. A box from Crosman arrived two days ago and I just looked at the shipping manifest (haven't opened the box yet). It contains a .22-caliber Benjamin Trail, so yes, I'll get right on it.

    B.B.


  48. Smallest ports,

    You know, it's been so many years since I did that test (1995) that I can't remember what the firing behavior was like with the smallest ports. But smoother would be my guess.

    B.B.


  49. HK,

    As far as I know, the copper plating on a lead pellet doesn't increase friction with the barrel, because it is so thin. The rifling still engraves the lead–not the copper plating, which simply conforms as the lead is deformed.

    I would not hesitate to use those Kodiaks in a 397.

    B.B.


  50. JC,

    I don't have a 46 or 460 Magnum to look at, but here is what I do know.

    The greater the volume of the transfer port, the lower the efficiency. And a central transfer port (that's centered on the compression chamber) is the most efficient location.

    B.B.


  51. I know this is offtopic, but BB do you have any idea when we'll find out who won the Valentines day (favorite airgun) contest Pyramid Air was running?

    J



  52. B.B.

    I noticed in Crosman's new catalog the Benjamin Trail NPs have weaver mounts. Do you know of any plans by Crosman to expand this feature to other products?

    Bub


  53. I'm thinking about making some Whiscombe Honey for pellet lube. You said to use 2 parts Hoppes to 1 part STP motor treatment. Which variety of both of those should I use?

    Not sure if there is more than one kind of STP, but I know that there are many different kinds of Hoppes.

    Thanks in advance for your help.




  54. J.,

    The contest judges will be reviewing the entries this coming week. The winning stories should be chosen shortly after that. I'm sure a formal announcement will be made as soon as the winners respond to Pyramyd Air's email regarding their entries & confirm eligibility.

    Edith




  55. Jane's comment about the Air Venturi port design makes me wonder about a funnel shape that narrows as it goes forward. Then, you would have air going out faster than it came in. Surely, there are tradeoffs, but I'm not sure what they would be. Perhaps narrowing the contact area of the escaping air with the pellet would cause problems. Or maybe enlarging the front end to enable narrowing subtracts from the efficiency of the transfer from spring to port.

    B.B., that's a good question about the ridges on the Olympic helmets. Jane would have to answer that question. But I do know that the Olympic swimsuits which have recently been banned for giving an unfair advantage are based on microscopic ridges to improve hydrodynamics. Here would seem to be a case where changing the airflow increases the efficiency unless the ridges somehow reverse turbulence created when the water contacts the skin. Anyway, the details are beyond me.

    Frank B., I have received a sharpener's dream: a Spetsnaz model shovel made by Cold Steel! The idea is to sharpen the whole edge to razor sharpness. That's enough metal removal to keep one happy for a long time. I'd say the Russians have done it again with this one (by way of an American design company that outsources its manufacturing to Taiwan). This thing would hit like a Viking battleax, but it's marvelously balanced. It's light in the hand like a medieval sword and is supposed to throw very well although I don't have the facilities to check. Despite its innocuous appearance, it has a superior heft and reach compared even to a bowie knife. Still, I'm not sure about claims that it is such a great concealed weapon. People would wonder why a person is carrying a shovel around unless they are gardening; maybe in a camping environment it would pass unnoticed. Actually, I suspect the Russian design is the latest in a long series of entrenching tools that have been used as weapons from antiquity. Anyway, I've got my hands on something nice although exactly what it's use will be I haven't decided.

    Jane, your opinion about the Beretta 92? I just read that the problem with cracked slides which caused the Navy Seals to replace these pistols with the Sig-Sauer P226 was caused entirely by army ammunition (M882) which had double the maximum pressure of NATO specs for the 9mm round. What is with the army? First, they screw up the M16 by using the wrong gunpowder, then they pull a bonehead mistake like this with the service pistol ammuntion. Unbelievable. Anyway, the Army Marksmanship Unit AMU is supposed to have Berettas that can shoot inside of an inch at 50 yards which I have never heard of before.

    Matt61



  56. I forgot to add that the shovel with the angles between the blade and the handle allows grabbing like that deadliest of polearms, the bill, which was a spear with a hook attached for pulling people off horseback.

    Best of all, the shovel, held at an angle at the appropriate place in front of the body, is supposed to make you bulletproof…. :-)

    Matt61


  57. Matt61,
    Bullet proof shovel: sounds like an episode for myth busters.

    Surface temp 84, water temp 79. Saw two more Lion Fish today. The exterminators – oops, I mean the researchers – can't keep up with them.
    -Chuck



  58. Well, the shovel wouldn't be my first choice of protection. However, if unfortunate enough to be faced with a gun muzzle, I'd certainly give it a try. If you recall the old trick about how axes can split a bullet that is fired just right, one supposes that there is a range of angles around this exact position at which the bullet will deflect instead of penetrate. As a matter of fact, medieval suits of armor were designed this way. Many parts were quite thin and not built to take a direct impact. They were curved into deflecting surfaces (hence some of the odd designs of later medieval German armor) to be used by a trained person who knew how to dodge. It would be a tough choice between throwing the shovel at the shooter or blocking with it….

    Chuck, where in the world are you now?

    Jane, what was your rimfire competition rifle? I've very curious.

    Matt61


  59. Everyone,

    Just because I am a wild and crazy guy, I will test the shovel theory. I'm guessing it will stop a rimfire and maybe a round ball .50 cal, but probably not a full-house .357. That's my guess.

    B.B.


  60. Mat61,
    I'm still in Bonaire, N.A., a desert island about 50 miles north of Venezuela, about 100 miles east of Aruba. Couldn't figure out how to get a seat for Ms. M and Mr T on Delta. Miss them much. Maybe She'll mingle with Mr. T while I'm gone and I'll have a batch of hybrid Talon/Marauder pistols when I get back.
    -Chuck



  61. BB,I seem to remember a bigbore airgun video ,maybe Dennis Q,where they were shooting at a shovel at 50 yards that was painted DOT orange.even with a tight group,the shovel was none the worse for wear!!Of course the shovel wasn't the star,the bigbore was!!I'll see if I can find the link….Hope you are feeling better:]




  62. RE: Transfer port & Rocket nozzles

    As Jane said we beat this up pretty good last time around.

    The major consideration is that there is a pressure differential between the two sides of the port. Gas flows from high pressure to low. A perfect de Laval nozzle would align the gas molecules in the flow so that they all have the same velocity and the gas molecules flow down the barrel without bumping sideways into each other. Of course there isn't any such thing as a perfect nozzle. Even if there were, the gas molecules still end up bumping into that pesky pellet which starts off with 0 velocity.

    The other point is that there is a big difference between a PCP and a springer. In A PCP the gas is at "room" temperature. However a springer heats the gas up as it compresses. The velocity of gas molecules depends on the temperature not the pressure. The higher the temperature, the faster the gas molecules move. temperature.

    Herb



  63. Mr B,
    Things aren't backwards yet, I'm still 12 degrees north of the equator.

    Fred,
    The wind blows so much here my hat won't stay on. Does that tell you something?
    -Chuck


  64. Fred,good for you!Cruising and sun are a magic combination.I took out my old Chrysler {1966} NY'er out for a shakedown cruise in the sun,all the windows open,lovin the weather!!!The sun at the flea mkt. was actually hot!The rumble of that old 440 thru headers and flo's was a perfect compliment to the day…though it's good at night too.But at night my cruising speed goes up a little{with every caution} Frank B




  65. In regards to changing your R-1 to .22 cal., you won't be sorry. An R-1 in .177 cal. is not using that power plant to it's full potential. This past summer I ordered a .22 cal. barrel, cocking link and link pin (it's easier to change over and back if you have a complete barrel/link assembly)from Beeman. It took about four months to get the parts and the barrel was stamped "THEOBEN". I should have figured right then that Beeman was in trouble.

    In light of present circumstances at Beeman I doubt you will get any parts from them now or ever. Your best bet may be from Weihrauch directly or Chambers in England. Eventually the Beeman branded German guns will be supported by someone here in the States but I'm not sure when all that will be sorted out. Jon F.



  66. SlingingLead,Ok to that!A big shot shooting his mouth off~A big shot……seems appropriate…..and fiscally responsible!I just finished knocking down the most recent coat of Tru-oil on the FWB stock.I just want to scream every time I put a new coat on….I don't deserve such beauty. Frank


  67. SL, Frank B, and Anonymous,
    Bonaire is about 20 miles long and 5 miles wide with a population of about 14,000. As best as I can tell there are no guns here. Therefore, I don't think I should be throwing rocks into a pack of 27,000,000 crocodiles.
    -Chuck


  68. Jon F,

    I've had a .25 cal R1 barrel assembly on order with Beeman since late October last year. They don't even return my calls. Even a call back to let me know it's not happening would be appreciated at this point.

    As far as getting one from HW in Germany, I've tried that route as well. They referred me back to the US importer–Beeman. Odd since Beeman referred me to HW in Germany…

    Stupid as this sounds, I believe the easiest way to get an R1 is .22 cal is to buy one then sell your .177 version to offset the cost. Sigh.



  69. Frank B,

    Did you rub out the Tru-oil in preparation for another coat or did you knock down the gloss (meaning it's finished?)

    What technique did you use to knock down the finish?

    kevin


  70. derrick38,

    I looked through my stuff for a spare rubber eye cup and couldn't find one.

    I'm assuming you need a rubber eye cup with a large diameter opening to accomodate a large disc rather than a rubber eye cup with a small opening to accomodate an iris?

    If you know the approximate size of the opening you're looking for I would encourage you to plead for one on the vintage forum. Lot's of very helpful folks there.

    kevin



  71. To Alan..I think a cyclone or other shape to create a vortex to "organize" the airflow through the port may help in one area, (faster total transfer), but hurt in another – by creating more sub-optimum collisions.

    At the molecular level, the pellet only moves because it is being bombarded by a series of collisions with air particles, (I envision them as marbles). Ideally, all of the air would flow through the port perfectly in line with the barrel. All of the collisions, [air-to-pellet, air-to-air, air-to-air-to-pellet, etc.] would be perfectly elastic and continously impart force vectors one one direction only.

    Any time a collision is off-angle, it will ultimately drive the marbles into the muzzle/barrel sidewalls, where the energy becomes heat. So, as it it, millions of air particles strike the sidewalls and we lose some of their kinetic energy as heat, I suspect we'd want to do nothing to encourage more of this.

    An interesting comment on intake runners and car engines. This area is where the most work has been done studying air flow. Manufacturers actually adjust the length of the runners to shift the torque peak of the engine. Column velocity becomes super-critical in high-revving engines, and you can hear the tone of them change dramtically as the inertia of the air starts to "supercharge" the cylinders.

    B.B. I have never really studied the ridges on the helmets, but their is an application of fluid dynamics that suggests these ridges prevent the air, (and water for swimmers), from clinging to the rounded surfaces. Boat racers have fought for years with this effect – fluids will cling mightily to rounded surfaces but not to straight ones. This clinging really slows them down, but they are forced to use the rounded surfaces to get stability and other effects they need.

    "Spoilers" are things added into air and fluid flow to reduce these effects. They break up the clinging, (in cars they originally broke up the laminar flow off the trunk lid), they break up vacuum and drag effects. I suspect we may see ridges on Americas Cup yachts now that they seem to have removed all of the rules.

    regards,

    Jane Hansen


  72. Matt:

    I also read about the Beretta cracks being induced by high-pressure ammunition in the M9. It hasn't been a problem in the last 15 years, and most of the US military still specifies the M9 as the standard side-arm. The US border patrol uses the 96, (same as the 92 in .40cal), although I suspect they really don't do a lot of shooting. (I've heard Seals avergae 1000+ rounds per week, but most others only qualify 2 or 4 times per year).

    I am waiting for the new 96A1, which Beretta claims has a cushioned recoil to reduce these failures.

    I also finally read the studies of the SOCOM tests for a return to the .45-cal. After reading all of that detail, I'm convinced the HK Mark-23 has to the the best .45 on the planet, but the darn thing is far to large for my hands, (and damn expensive).

    If you hear of the 96A1 hitting the market, let me know. It will be my next purchase, (although I will not like it as much as my P-226).

    regards,

    Jane


  73. To Wacky Wayne:

    I am interested to hear more about your thoughts on the Blizzard. It was your original comments that induced me to buy one.

    I was hoping for a rifle near as powerful as the Infinity, but more refined and accurate like the S410.

    It's a great rifle. However, it would benefit from a power adjuster. As a hunter, I only need a dozen shots, but I need to know where they are going to go, and the velocity of the Blizzard falls off rather fast with heavy pellets. The Infinity falls off faster, but by dialing the power my POI stays on and I still have a fast, flat, trajectory.

    The Blizzard is a large gun. It has the potential to carry a lot of air, and deliver a lot of power and accuracy, but it needs some tweaks. One thing it needs very quickly is a new clip – having the pellets slip and hang up is simply unacceptable.

    regards,

    Jane


  74. Jane,

    At what velocity above the sound barrier does a supersonic diabolo pellet become stable again?

    How bad is the effect on the flight path after dropping subsonic again?

    Thanks,
    AlanL


  75. Kevin,

    Why do divers fall backwards when they're entering the water. Cause if they fall frontwards they'll land in the boat. Just wanted Chuck to enjoy his trip without any untoward incidences.

    Absolutly nothing to do with the breading habits of Mr T and Ms M.

    Mr B



  76. Jane,

    I'm with you on the power adjuster added to Evanix Blizzard… really all PCPs can benefit from one.

    It's a great way, as you say, to get more shots on POI. Just start out with the adjuster set at 85% full power, and then you can turn up to full power as the tank empties…. sort of works like a regulator, but gives you the option to dial it down real low for more shots when plinking.

    I think that the Air Arms s410 in .22 cal could be tweaked by Bori or someone, to increase the foot lbs to that of a Blizzard. Then you'd have the best of all worlds… high quality, .22 rimfire power, probably 30 shots on POI, and a very quiet gun.

    I also think a power adjuster could be installed on the Blizzard.

    Have you tried the 21gr Kodiak in the Blizzard? I seem to remember them working in the magazine and grouping very well.

    Wacky Wayne, MD, Ashland Air Rifle Range


  77. this is off topic but can the crosman airsource setup for the 1077 be used on the 2260? I imagine that the 2260 stock would have to be modified, but would the internal CO2 stuff match?





  78. also on the airsource – call me crazy, but why turn the airsource connector so the tank is pointed forward. I think the penalty of the extra weight forward would be offset by the ability to hold the stock in the traditional shooting style. just saying.


  79. BB
    Thanks, I was hoping that would be the case. I'll get in touch with them in a couple weeks. I blew my airgun budget yesterday. Six or seven new guns in the last month. I'm feeling like the shallow pocket version of Wayne.
    What you said about second mortgages and collecting hits home!

    Kevin,
    Thanks for checking. The rubber cup I'm loking for will fit over a roughly 1" diameter edge on the aperture. Something like the rubber eyecup on this sight:

    http://www.pyramydair.com/s/a/Daisy_Avanti_Precision_Rear_Diopter_Sight/1212

    I'll call Daisy Monday and see if I can get one. I'm guessing they're about $15. Want to add one to a Crosman 411 aperture sight. I'll have to make a new disc that will accept the eye cup.


  80. Wayne:

    The Blizzard grouped very well at 35yds with Kodiaks but only for the first 12 – 15 shots. I hunt with heavy Eunjins and try to reach out farther, and it needs a bit more power for those. I don't really use the lighter ones, except in the S410, which is my preferred rifle for smaller pests and birds.

    Alan L.
    I'm not sure I understood your question, but I'll try. We like to think that as long a projectile is ahead of it's sound wave, (by even just a little), it's fine. This means a pellet would need to exit the muzzle supersonic, and stay supersonic till it hits the target. Because the atmosphere has gradient temperatures, pressures, and winds, that generally means 1200FPS+.

    There is no way to guarantee that a pellet will re-stabilize after it crosses the sound barrier, whether on the way up, or down. (One can assume that if it's still in the barrel on the way up, it will exit the muzzle stable.

    The diabolo design is not really "severe" enough to restabilize a badly shaken pellet. I don't think it was conceived to cross the sound barrier. They can sometimes acquire a wobble or other oscilation that they simply won't shake.

    Matt:
    I forgot to answer your other question, on target rifles. I was a Walther girl in a world of Winchester 52's. The E-series 52 was extremely highly regarded, but my parents were German and always thought the Walthers were much better rifles.

    Did I see someone mention a 440 Chrysler? Dad was a Mopar guy – 1968 GTX with the same 440cid. He drove it for 20 years….

    regards,

    Jane



  81. Replacement barrel,

    If PA does not have a .22 cal HW barrel available, what Derrick suggests sounds reasonable. I would buy the used .22 cal rifle first and keep the “best of” stock and receiver and sell the left over’s on the yellow. My purchase was made before the internet and such a course of action would not have been possible. In fact, after about ten years the .177 barrel got lost in the shuffle and when in turned up looked more like a rusted piece of rebar. It would have been a quick sale now.

    Volvo


  82. BB
    Hey was watchin the winter olympics and was wondering what kind of rifles they were using in the 15km cross country biathlon(if thats what its called) i noticed the aperture sights but they had to shoot 5 shots each from 4 different positions then throw the rifle on their back and keep goin. kudos to these guys for being able to shoot in between racing like that. i was in awe
    -orozco


  83. Kevin,I ran into the same issues you discussed with the RLO…Then I tried some Formby's,but I didn't have alot of confidence with it.large flat surfaces it would be great for.Tried the Tru-oil,builds real fast and even!!Because of those properties,I take down most of each coat after it dries with 0000 steel wool.Then I clean it twice with blue shoptowels,second time with a little mineral spirits.Almost perfect,when I get blem free,I plan a THIN final coat with Tru-oil.I'm not good,just trying real hard!!! Frank B


  84. Frank B,

    Thanks for the update. Wondered how things were going with the RLO.

    Glad to hear you like the tru-oil.

    You may want to try bronze wool. Doesn't shed as much as steel. If particles of steel wool get in your finish they could rust. Mineral spirits for cleaning up the steel wool mess sounds ok but for you final coats you may want to use a tack cloth instead. High pressure air works well too especially on checkering but you don't have that issue (yet?).

    kevin



  85. B.B.

    To be fair to the shovel, it needs to be at an angle to the bullet path–no less acute than 45 degrees. Otherwise, this is just a test of penetration power, and I don't think anyone in their right mind would hold the shovel at right angles to an incoming bullet.

    Frank B., the darn shovel has slight curves on the edges, less than most shovels, but still there which will make this a very slow sharpening process. I'll need to make use of your ceramic rod. By the way, I can identify with the thrills of your car. My rc car broke down, and I'm crushed. But I learned a little more about tinkering in the process of taking it apart.

    Chuck, you're out of control. Never heard of your hideaway.

    Jane, pursuing the marble model for molecules, wouldn't the collision with the side of a chamber be largely elastic without losing much heat? I know that the barrels of firearms get hot as hell very quickly. But I've never experienced nor heard of airgun barrels getting hot, no matter how much you shoot them.

    You've made clear to me the notion of parasitic drag which I've read about in connection with rc airplanes. Perhaps this concept and the ridges on Olympic helmets suggest another idea. With tiny, longitudinal (parallel with axis) ridges in the transfer port, maybe one could decrease parasitic drag and speed up the air molecules that way.

    I too encountered the famous Winchester 52 on my high school rifle team. They were beat up and not impressive, but I think that reflects more their heavy use as club guns than their intrinsic quality. Walther is a good brand, but you should have worked the German angle to have your parents get you an Anschutz. As Marine DIs would say, I was not worthy of that weapon when I had it.

    Apparently the HK 23 is too big for the special forces as well. Even if they can hold it, there seems to be no tactical use for a pistol of that size. Supposedly, though, the HK USP is a cut-down version of the same design which, you would think, has its virtues. I believe that the German naval commandos use it as a sidearm. However, in the write-ups, the HK USP does not really seem to distinguish itself compared to the SIG and other .45s.

    orozco, wondered the same thing about biathlon rifles. The current Anschutz model appears to be the 1827 Fortnoy. It has a precision smallbore action with a detachable magazine (for rapid fire and reloads) and a more straight line stock than a position rifle for easy carrying. The action works with a finger lever for rapid-fire that is supposed to be almost as fast as a semi-auto. I picture something similar to the S410 sidelever.

    Matt61


  86. Gentlemen and Ladies,

    I have had to replace an attic fan and blow acorn shells off the intake manifold of my car one too many times. As respects the attic fan, a tree rat had apparently pushed it's way through the ridge vent (pie plate?) and tried to get into the attic but apparently hit the spinning blades. Those sob's are tough as the blades bent and jammed against the housing, killing the motor with the stalled rotor current. No sign of any tree rat, however.

    Enough was enough. So while everyone was dreaming of Mopar, watching the biathlon or chasing their hats, I camped out in daughters' bedroom with my trusty Discovery equipped with Mike T's trigger mod and muzzle brake and 5×15 x 40 Bushnell Elite scope.

    Now this next part really made my day but at 15 yards shooting down, off-hand, I took out two squirrels with two head shots – one each!

    Although wifey wasn't happy when I told her what I did (she never heard a thing), that should make things last a bit longer around here. I have to go out when it's dark so the neighbors don't see me, and pick up the carcasses.

    What a really neat rifle that Discovery is and everyone says the Marauder is even more accurate?

    Hmmmmmm.

    From the People's Republic of NJ

    Fred PRoNJ

    wv: uncia – not sure what this means


  87. Matt:

    In the real world there are no perfectly elastic collisions. When the air molecules hit the barrel side walls, they do indeed impart some of their energy, which we can measure as heat.

    It's probably not something we can feel, (it's hard to shoot a springer as fast as it can dissipate the heat), but for sure it is happening.

    regards,

    Jane


  88. Jane H.,your dad's 440 could have used your current aptitude towards flow dynamics.The 440 in my car has tremendous potential,but initially came breathing through a very flat intake manifold with severe turns and restrictive passages.The exaust was equally dismal in design.I have corrected all of that with a highrise dual plane intake and long tube headers.The stock heads have been ported and polished too….it probably flows 25% more air now!!!I know it flows plenty of gasoline….12 mpg downhill!!!


  89. Re: The TX200

    I was shooting at 10 yards indoors. The first shot was loud. Also POI had changed from where it had stayed zeroed for months. Then I noticed the twang, buzz, and vibration. It used to fire so smoothly. The vibration seemed to build to a crescendo over 10 or so successive shots, and then settled down. At one point it actually stung my hand to hold the grip, it was vibrating so badly. POI continued to shift left and up during these shots.

    A couple days later, I took it to fire at at 40 yards. The 10 shot group was probably 7 inches. POI was way off, so much so that I missed the trap a couple times until I figured out how far right I had to hold it.

    I shot 7 pellets through the Diana52 to see if it was me, and I was rattled, but shot a group the size of a quarter. The 52 feels smoother than the TX does now.

    The POI shift and total inaccuracy sound like a scope or mount problem to me. But I checked, and tightened, just slightly all the screws. Including stock screws. The initial vibration and continuing harshness seem like a mainspring or guide problem, but don't understand how accuracy would suffer to this extent.

    I'm considering sending it to PA at this point.


  90. Frank B.,

    did you have a 5 angle or radiused valve job done? That really does help air flow and should aid turbulence in the cylinder (which is a good thing here).

    Funny that with the huge engines the Americans had, no one bothered with tuned intake or exhaust headers or even tuning the airbox volume. With their smaller (1.6L) engines, the Japanese needed to do this to get the most out of them for the American market. Now the Americans calculate the intake manifold length to get a better, lower torque curve. Not sure if they also take this type of care with the exhaust headers or try to get as free flowing an exhaust as possible. The real gearheads should know.

    Fred PRoNJ


  91. Frank B

    When you said you had a '66 New Yorker, I thought I knew exactly what your model car looked like. I jumped on the internet to see if I was right and discovered…
    The New Yorker magazine employs 66 staff writers. Weird!

    What model is your motorcycle? Would love to see a pic of your hog parked next to your 66 if you have one laying around on your hard drive. Judging by that FWB, I think the rest of your toys are probably very nice too.


  92. Fred,now you're talking my language…some of us americans got it,it was just hit or miss.they would make a motor like mine,and choke the top off it's potential flow performance.Case and point:a motor that makes 485ft.lbs. @ 2800rpm should easily surpass 350hp with a 5300 rpm redline.It had an aircleaner you could block completely with a golfball!!!we're talking about a 4.3 inch bore with a 3.75 stroke.That's like an R1 with a.080 transfer port….anyway 3 angle grind and deshrouded the valves,hardened seats and bronze guides,to answer your questions.


  93. SlingingLead,unfortunately no hog for me…low back issues make that a bad idea.Not that I haven't thought about it but I think it would be an old BMW bike….the kind they used to race sidecars with before ww2.Flat black would give it a sinister presence.BMW was so far ahead…electric start and shaft drive in the 30's!!


  94. Frank B.,

    I should have known better – of course you would take care of breathing at the head!

    Slinging Lead, I used to have Harleys, 2 in fact, but I got bored going slow :). By the way, I found an Israeli company, of all things, that make some neat bicycle jerseys (you and Derrick38 are into bicycles big time, right?). If you're interested, go to http://www.funkier.com

    Fred PRoNJ


  95. Re: The ridges on the women's helmets/fluid dynamics.

    This looks to be an application of the tubercle effect, which has been studied by professor Frank Fish of West Chester University.

    He found that the softball sized bumps on the leading edge of humpback whales fins called tubercles helped them to slice through the water faster, even though the opposite would seem to be true. The tubercles seem to break up the stream of particles of water (or air) and make the fin have less drag.

    He applied the principal to industrial fan blades, and his designs require 20-40% less energy than traditional blade designs. Wind turbines look to be the next application of his discovery. He started a company called Whalepower to bring his idea to market and was a 2009 INDEX: award finalist. This is an international design competition hosted by Denmark.


  96. RE: Heat transfer to/from barrel

    Heat transfer to/from the barrel is not a problem in air guns. The problem is that gas is a compressible fluid. This creates compression waves which inhibit the flow of gas down the barrel. Molecules bouncing off the walls (and most of the rear of the pellet) of course create the compressions.

    Herb


  97. TO BB – PLEASE REST IF YOU ARE SICK AND GET WELL SOON!!!!!

    The Benji trail sounds like a nice combo. If it can shoot and have some power, it should really be a good AR for the money.


  98. !@#$%^&*

    Forgot another important point, which Jane raised when she outed herself as a rocket scientist! As I remember she asked about the SHAPE of the transfer port, not just its internal diameter. The point was that a better shape might significantly improve the flow through the port. This I think is still an open question.

    In a PCP the valve and the transfer port are intertwined, so there is probably less room for improvement. But for a springer, it would seem that some design work might result in an improvement. The shape would be a tweak, with the diameter of the port being a more significant factor. But 10% more velocity is 10% more velocity.

    Herb


  99. Jane,

    You understood me perfectly although I expressed myself poorly. I know that a pellet undergoes all kinds of weird forces and turbulence that can destabilize it when it goes through the sound barrier, so I wondered whether actually flying ahead of the pressure wave had any further destabilizing effects. What you said about this effect being negated or minimized by occurring while still in the tightly controlled environment of the rifled bore is very reassuring; it means that a supersonic pellet can reasonably be expected to remain on a stable flight path while it is so. But since since all pellets in flight lose velocity so quickly due to friction in air, I wondered how bad the destabilizing effect would be upon recrossing the barrier back into subsonic velocities.

    The point of my query was to help me decide whether a really powerful magnum springer like the Talon or Diana 460 is worth it, and can reasonably be expected to maintain accuracy while still packing that powerful punch at 50 yards.

    Can anyone recommend a spring piston rifle that will shoot a .22 caliber pellet at above 1100 fps and keep it there for 50 yards (at least in a no wind environment)?


  100. AlanL
    “.22 caliber pellet at above 1100 fps and keep it there for 50 yards” Why? If that is really what you need, get a Ruger10/22.
    Pellets are not designed to be accurate at those velocities, nor any spring rifles. As power increases shooters use a heavier pellet to reduce the velocity and maintain accuracy.

    What is your goal for the rifle you seek?


  101. Alan,

    There isn't any airgun that will fling a pellet above the velocity of sound for 50 yards. That is everyone's fantasy airgun.

    In general those of us in the city also want something quiet. A supersonic pellet isn't going to be quiet either. The pellet itself would make noise not just the muzzle report.

    Herb


  102. Volvo, Herb,

    I suspected as much. Too bad. I just wanted to pack a big punch at 50 yards accurately without going away from an airgun. Big iguanas cannot easily be stopped with less and typically don't let you get closer than 30 yards.

    -AlanL





  103. Fred, actually that's not quite true. There were several applications of both tuned intakes and exhausts in cars of the 60's. The science wasn't nearly as developed as is is now, and the application was far from universal, but it certainly wasn't unknown. Since the subject was broached about Chryslers, there was the dual-carb cross-ram setup introduced, I think, in 1960. The hi-rise intake and tri-Y headers on the mid-60's Shelby small-blocks were other examples. Even the small ports original to that 440 were almost certainly selected for their driving characteristics – low end torque and good fuel atomization. Heck, virtually every grocery-getter 2-bbl V8 of the period had a 'cross-H' manifold that was designed to evenly separate the intake pulses so as to improve fuel metering and cylinder-to-cylinder consistency.


  104. AlanL,

    Children often baulk at trying something new on the menu, but when parents make them take just one bite, surprise, they like it.

    FYI – you’ll own one soon, but don’t really try and eat your PCP.

    Volvo


  105. AlanL,

    You are asking the right questions. Instead of asking which rifles will defy the laws of physics and send a diabolo pellet to 50 yards while supersonic, you should ask which air rifles will kill big iguanas at 50 yards. If any will, I suspect it would be the Condor from AirForce.

    A diabolo pellet is like a badminton birdie. You can whack the hell out of them, but they will still slow down at the net.

    B.B.


  106. Volvo,

    The older I get the more childlike I become… are those pcp's green too?
    aaarrrrgh!!

    Kevin,

    I know I know, the 'right' one is the S410. Maybe with one of your beautifully refinished stocks? ;-)

    B.B.,

    A condor killing iguanas? Hmmm… now that would be a sight to see!

    AlanL


  107. Sli9nging Lead,

    Your TX has something broken inside the powerplant, I'll bet. It could be the spring guide or it could be the mainspring.

    Since the TX 200 is one of the easiest springers to work on (no mainspring compressor is needed) why not take a look yourself? I show part of that disassembly here:

    http://www.pyramydair.com/blog/2006/07/spring-gun-tuning-part-8-disassembly.html

    If you want, I will do a special report on how to disassemble a TX 200 that should be easy enough to follow.

    B.B.


  108. B.B.,

    Yes, please do! I am still toying with the idea of getting a TX200, keeping in mind your comment that you liked this rifle very much in .177 cal. (now that I've given up my search for a springer that'll shoot a .22 at 3000 fps!)

    Just be sure to include many nice detailed pics that even an idiot like me can follow.

    -AlanL


  109. Kevin,

    I was off in a congress, I saw the last 4 blogs today. I am still trying to catch my breath after looking at that Fwb stock. And I was proud of mine (no scratch on it after 28 years). You're quite a artist.

    AlanL,

    I have shot many big iguanas (tasty!) and learned that those damn reptiles can take a LOT of damage without falling off the tree. Really tough. I saw one taking at least 6 .22 LR shots before falling down, another ones even needed a kiss with the 12 ga to get convinced. So, in this particular case, get the stronger airgun you can.

    BB,

    I received my package today! You're a very, very kind man. I still dream about having a uncle like you. I hope you will get well soon.

    Anthony


  110. HK,

    I dont know if it will be useful. But lead poisoning is only of concern after years of exposure. And it only gets absorbed by mucous surfaces (mouth, lungs). So, if you wash your hands after every shooting session, and use a reliable pellet trap, you will never have detectable levels of lead in your body or any problem. The only cases of lead poisoning (saturnism)I have seen are of industry workers exposed to fumes. Otherwise, it is very rare.

    Greetings,
    Anthony



  111. Why so few magazine/revolver type spring or gas ram powered Air Rifles? I would love a Diana 48 side lever with a 6-12 shot reveolver type magazine. Sure would make shooting in the cold a lot more pleasurable as I wouldn't be dropping pellets trying to load them one by one while freezing bare fingers.

    How about a survey article on repeating springers/gas ram rifles?


  112. Repeating spring rifles have been spectacularly unsuccessful. Most of them have severe feeding problems and none of them will feed all ammunition. The spring-air design is best-suited to a single-shot.

    B.B.


  113. Repeating Spring Rifle,

    B.B. has posted two reviews of repeating spring rifles that I'm aware of on this very blog: the RM-2800 and the RM-2000. They both feature a linear feeding mechanism rather than a rotary mechanism, which might work better. As he mentioned above, repeating spring rifles haven't been very successful for some reason. They seem to have trouble feeding and issues with leaking since they all feature two breech seals to give you trouble.

    I feel your pain regarding loading pellets in the cold. In fact, it bothered me so much this last year while hunting with my break-barrels that I purchased one of the pellet pen gadgets which allow easy loading of the gun while wearing gloves. I bought the Crosman Pellet loader because it was available locally. There's also the Pellet Pen. Both of these are available from Pyramyd Air for reasonable money. I've been very satisfied with the Crosman loader and would highly recommend it.


  114. Anonymous, you're close to describing the 8-shot underlever RWS/Diana 300R. I have one and have worked on a few. Mine is extremely accurate and easy to shoot well, and the repeating mechanism feeds and fires reliably. One example that I worked on shot in my hands the best 5-shot group I ever shot with a .177 – about .17" ctc at 12 yards.

    But that's if you NEVER operate it incorrectly. Forget to cock the gun before trying to remove the magazine, and you break the feed pin and the mag won't come out. Cock the gun to then get the mag out and you've just broken the mag. Jiggle the gun while trying to remove the mag with the gun cocked and the broken pin falls in front of the compression tube necessitating a teardown to remove it.

    There are so many things you can do wrong that will double-feed pellets or break the magazine or break the feeding pin attached to the front of the cylinder. I cooked up a full page of special instructions to cover the operational idiosyncrasies of that rifle… or at least the ones I've found out about.

    BB's right. There's a reason why virtually all pellet rifles are single-shot!


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