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Rifling revolutionized!

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Outside the box
  • Rosenthal award
  • Rifling
  • How it works
  • Outside rifling?
  • Accuracy
  • Range increased by orders of magnitude!
  • Trouble brews
  • What is to come?
  • Rumors are flying!
  • Summary

Outside the box

I’m sure you have heard the phrase, “Think outside the box.” Many organizations don’t really want their people to do that. The organization just wants their employees to enlarge the box a little, but to continue to respect the time-honored principals that got the organization to where it is today.

Rosenthal award

But there are exceptions. In engineering there is an annual Sol Rosenthal Award for the creative idea that best advances its technology that year. Unlike many awards, there is only one caveat to this one. A prototype of the idea must be implemented, so it can be compared to an existing reality that can be measured.

The idea does not have to be an object. For instance, in 1978 a high school student in Twinsburg, Ohio, created a roundabout to replace a busy intersection in town that had a 4-way stop. The student demonstrated her idea on the stage of her school’s auditorium to the town council who was so impressed that they redirected $875,000 in highway repair funds to create an actual roundabout in town. The throughput of traffic at the selected intersection increased by 27 percent and accidents decreased by an astounding 31 percent — fatal accidents by 100 percent!

The result of this idea from a high school student is now the tens of thousands of roundabouts that have been installed or are under construction all around the United States. Fifteen-year-old Anita Carson won the 1978 Rosenthal Award of $250,000, and today Dr. Carson runs her own successful traffic analysis and management planning group in Fairfax, Virginia.


In 2019 a graduate student at Stanford University in California, created a novel new type of rifling. Instead of a tube with lands and grooves inside, Thomas Manke made a rod that is rifled on the outside! He claimed there are numerous advantages to this form of rifling, the principal one being access to the lands and grooves. Manke says barrelmakers who use his process will have a much easier time both creating the rifling as well as perfecting it after it has been created.

Manke had to build a prototype to demonstrate his idea, so he used an airgun — a Benjamin Discovery that he modified. The idea is difficult to envision, so I will explain it now.

Benjamin Discovery
Manke’s modified Discovery. Photo provided by Thomas Manke.

How it works

A normal barrel develops pressure behind a projectile inside a tube. Since the pressure is too great for the projectile to resist, it pushes the projectile out of the barrel with force. Hundreds of years ago the inside of a barrel was smooth and only the straightness of the barrel directed the projectile to fly along a reasonably predictable path.

Some time after guns were first invented someone put grooves in the barrel with the thought of containing all the soot and ash from the burned gunpowder. At first the grooves were straight but then someone decided if they were cut in a spiral they would be longer and collect more residue. That didn’t work, but the spiral grooves did cause the projectile to spin, and its accuracy improved dramatically. The people who did all this are lost to history, despite what claims you may read, but the idea of rifling caught on and has advanced to its very high state today.

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Outside rifling?

If the rifling is on the outside of a rod instead of inside a tube, how does the projectile get its push? Manke uses a larger and shorter tube on the outside rear of the rifled rod and his projectile fits inside that tube and around the rifled rod. Therefore, you may envision a Manke projectile as a disk. The outer edge seals the bore of the short hollow tube and the inner edge is engraved by the rifled rod. A Manke projectile is a flying disk!

Manke disk
The Manke disk is a donut-shape that fits around the rifled rod and inside the hollow tube.

The rifled rod doesn’t need to be very long. As long as it is about one inch past the end of the outer hollow tube, everything works as it should.

Manke system cross-section
The Manke system is simply a reverse of a conventional rifled barrel.

Testing the MD

Manke created his testbed rifle in 10 days by modifying a Benjamin Discovery. He said he used the Disco because it was the cheapest PCP he could find, but that almost any PCP can be modified to accept his disks. He also said there is no reason why spring-piston guns and CO2 guns cannot use his system with equal success.


Manke’s first test astounded even him. When the disk leaves the end of the rifled rod, air pressure causes it to tip and fly flat toward the target. It is spinning from the rifling, of course. He also discovered that he can alter the orientation of the flying disk by rotating the rifled rod, because apparently when the disk leaves the rod it orients according to its last contact.

After sighting in his testbed rifle Manke shot a 5-shot group at 25 meters that measures o.o-inches between centers. It was this group that was submitted with his patent application, as well as his doctoral dissertation and is shown here with special permission.

Manke bull
Manke’s first target was shot at 25 yards. Five disks were fired and there is no discernible separation of their impact points. The rifled rod was turned a precise amount for each shot. This is a 0.0-inch group. Photo provided by Thomas Manke and yes, the bull is upside-down.

Range increased by orders of magnitude!

Manke also discovered that his disks can be made to fly much farther than conventional bullets of similar weight. His 7.74 mm disks are made of lead and weigh 35 grains, but he says he can alter the weight within limits by changing the thickness of the disk. If they are fired perpendicular to gravity they act like Frisbees, flying as much at 20 times farther than a conventional bullet of the same weight and speed. If they are oriented vertical they have remarkable resistance to crosswind, though they do fall to earth just as fast as a conventional projectile.

Trouble brews

Manke did not develop his idea for the Rosenthal Award. It was the foundation of his doctoral dissertation. However, one of his faculty committee members withdrew after learning that an airgun was the basis for his proof. He said as he withdrew, “Mr. Manke has shown himself to be a very bright engineering student, but his involvement with firearms that shoot lead projectiles is not in good moral taste. Surely he must be aware that lead is known to the state of California to cause cancer and birth defects or other reproductive harm. And firearms are socially wrong from a moral standpoint.”

The dissenting faculty member was allowed to remove himself and was replaced by the head of the engineering department, who then submitted Manke’s idea to the Rosenthal Award committee.  He also announced that the Defense Advanced Research Projects Agency (DARPA) was offering Stanford an open-ended grant to investigate Manke’s thesis. Their stipulation was based on the university retaining Manke as the principal investigator. The university president responded that Dr. Manke would indeed be allowed to continue his research as a new tenured chair of the mechanical engineering department.

What is to come?

There is no doubt that Dr. Manke’s invention is going to have a major impact upon both firearms and airguns. In an interview given on Fox News Manke himself gave just a single example. What changes will result from a sniper weapon being able to fire with accuracy to 20 miles? DARPA has asked him not to speculate further, but Lieutenant General Robertson, the agency’s spokesperson, stated that this invention is as fundamental as the wheel. There will be no way to protect the patent, because anyone who tries it will get the same results. He said, “This is not nuclear science. This is fundamental physics that any child can replicate!”

Dr. Manke will be exploring many other aspects and problems of the disk. For example, it will be difficult, if not impossible, to get disks that weigh as much as bullets of the same caliber. That may have consequences that are both good and bad, and Dr. Manke wants to identify those consequences as soon as possible so exploration can begin.

Rumors are flying!

People who have heard about Manke’s discovery are talking! I can tell you that as far as I know there is no truth to the rumor that FX is considering calling their version of the outside rifling a Smooth Twist Three barrel.


Sometimes we go for a long time with not much advancement in the world of ballistics. And then something comes along that changes everything overnight. Dr. Thomas Manke’s discovery has opened a new door in the world of unguided ballistics.

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.

79 thoughts on “Rifling revolutionized!”

  1. B.B.,

    Dr. Manke is going to be a wealthy man! This ammo will fly just like Frizbie! It also probably solves a bunch of Balistics issues that pellets, B.B.s, and SLUGS share! No magnus effect but the MANKE effect: https://www.urbandictionary.com/define.php?term=manke
    I wonder if Sol Rosenthal is Andy Rosenthal’s Dad? I went to school at Bullis Prep back when it was in Silver Spring MD. Andy’s dad, of the very successful Rosenthal Automotive Group, dominated the DC Metro areas car and truck sales. He was always looking for ways to fund Out of the Box ideas!

    In the third paragraph, 1st sentence of Rosenthal Award:
    “The result of this idea from a high school student is (how) now the tens of thousands of roundabouts that have been installed or are under construction all around the United States. Pretty manky if you ask me!


  2. BB,

    Fine article! You fail to explain how the inner rifled rod is held in place. Is this a break barrel type gun? Is there a magazine full of disc at the ready? Or, is this a muzzle loader concept? 😉 (x10)

    I see no reason that a barrel that had a (slot bore) in it could not fire a disc/washer type projectile. Extruded aluminum maybe? Round steel tube hammer forged over a flat bar/mandrel. Myself, I would use a 4 piece barrel (top, bottom, 2 sides) bar stock, laminated together to test. Precision washer/disc ammo could be easily obtained through a place like McMaster Carr. I would start with simple bench mounted test jig with PCP being the power source.

    It would be interesting to see what would happen. Actually, I would be surprised if someone has not already tried a disc launching gun,…. other than the toy version that many of us remember from our youth days.



    Check this out!!!!! https://www.youtube.com/watch?v=iYoJ88Hk7fM I want one!!!!

    And yet another version https://www.youtube.com/watch?v=9cHYn0vm4u4

      • Michael,

        They aren’t shown in the simplified drawing B.B. chose to illustrate the basics. I checked on line and Dr. Manke has one showing the series of NACA Vents surrounding the bore at the receiver end ;^)


    • Chris, oh, that takes me back! My sister and I got those one Christmas, and promptly lost the disks under furniture, and then when we got kicked out of the house, buried in the snow outside, all shot away. We found some in the spring, along with, yup, all the pennies we replaced them with. Those were worth a whole cent back then! It helped to “punch” the gun out toward the target while shooting for an extra couple fps; must be where I picked up that bad habit…
      We also got these Zebra pistols one year that shot yellow rubber bbs, they came stuck to a “tree” that left a dimple but still shot better than the disks.
      Fortunately that year we also got a whole box of ammo!

      And thanks, BB, you had me until that target!


      • Mike,

        In my youth, I seem to remember the paper caps rolls that had a wee bit of powder in each dot. Shot them in Cowboy “revolvers.” I am sure we had other ammo type guns as well. With 5 kids then,… squirt guns were big!


  3. BB,

    I can see a serious issue arising due to aerodynamics. The accurate range and velocity of the present “washer” shape will be limited due the thickness and flat edge of the “projectile”, such as a wadcutter versus a conical bullet. For true long range shooting the washer will need to be double convex surfaced with sharp edging on the outer edge and inner edge. Application of rifling to the inner edge will have some effect possibly creating turbulence but if the proper twist rate is applied with the proper number and depth of “lands and grooves”, this deformation of the inner edge can be used to direct air through the hole where it can be used to provide additional lift thereby increasing the range.

    This effect could also be utilized say in a soldier’s shoulder weapon where by having a knob or dial by which the soldier could rotate the inner rod to allow this “push” of air to direct the projectile to the left or right and thereby shoot around corners without exposure of the soldier or weapon. A slight variation could also be used to correct for crosswind.

    Addendum: This aerodynamic shape will reduce any “whistling” effect of the projectile, as this is caused by turbulence which is undesirable as it will effect range and accuracy.

  4. Maybe it could be modified to shoot coins. A modern coin thrower. Who would of thought.

    Hope everyone is off to a good start for the month of April. I was wondering what today’s report would be about. 😉

    • GF1,

      Here is a penny shooter, https://www.youtube.com/watch?v=cDgXfsYr1Do

      And here is a common ink pen, rubber band and ink cartridge,… that will shoot through (both) sides of an aluminum Coke can, https://www.youtube.com/watch?v=7YFQnF1eD_w

      Both kind of illustrate that while you may not have much FPS,… with the right mass and projectile you can have some FPE. The Coke can (full) was impressive. That would penetrate skin for sure!

      Now,…. what all do I have laying around????? 🙂 LOL!


      I’ll bet Shootski knows how to make improvisational weaponry? 😉

      • Chris
        You remember BB’s report on the toll bridge gun. That’s what I was referring to about a coin throwing gun.

        Search it and see what I’m talking about.

          • BB,

            Thanks. I had not got around to looking it up yet. Too busy looking at all of the You Tube homemade toy shooting related projects,… which leads to?,…. which leads to?,…. which leads to?,….. In the end,… I found my self looking at how to make deadly blow gun darts with Amazon region poisonous frog slime. Apparently,… getting warts while handling said frog is the least of the things you need to be worried about! Not sure if you can relate or not? 😉


        • Shootski,

          Never having been a Navy SEAL,… (movie fantasy aside),… 😉 I would take that to mean,.. to always have a back up? A back up weapon and back up plan?


          • Chris USA,

            Having worked with SEAL Teams and other SpecOps units they have that fantastic capability reputation based on great preparations and the ability to realize the plan is starting to fail and then improvise, using skills fine tuned during their continuous training, to complete the mission. I never noticed that they used the concept of a backup plan or weapon the way most other folks organizations think of them! If one is none and two is one that creates the question; is a backup having a third plan/thing? That’s why i say they don’t think in terms of backups.
            I remember in flying the FAA, ICAO, and many Military Commands require planning for fuel to fly to your destination and to an alternate landing location dependent on weather minimums. It made sense back in the days of questionable/unreliable radio communication, primitive instrument flying systems and very primative weather forcasting. But, carrying extra fuel wastes tons of fuel tankering it from place to place and also reduces the aircraft payload ton for ton. There were also the pilots who added extra “just in case” fuel on top of that. If you actually dipped (physically measured) your fuel tanks and then ran fuel consumption logs you could overcome most of the minimum fuel remaining requirements on landing being added to all the above extra fuel. In the end after all that backup fuel to be sure you didn’t run out of fuel resulted in 1/4 or more of the fuel tank capacity being occupied by useless fuel! About 8-10 tons of fuel easily on one aircraft i flew. So backup anything is really a logistics killer especially in a combat/war fighting system. In doing all that backing up you reduce your fighting capabilities by 1/4!
            That IS why Special Operators are so, so, so much more effective than regular troops can ever hope to be. I could write a book about tactical logistics disasters in every one of our wars from the Revolutionary War onward right up to Afghanistan and the introduction of Regular/Reserve (long and large logistical tail) Military Units.


            • Shootski,

              As always,… thank you for your insight. Train well, plan well and have the skills to adapt and improvise along the way in the most extreme sense.


  5. B.B.
    Oh you didn’t. Yes you did. It’s only the second time since I’ve been reading the blogs, but you got me. It wasn’t until I read the first comment (by Siraniko) that mentions the date! LOL, I forgot about about the date. Ugh. The other time you got me was the PA break barrel big bore that wasn’t hold sensitive and would be about $100. Geez.


  6. Hmmmm…let me see…this smells like “April Fools” to me.
    A search on “Dr. Thomas Manke and his outside rifling gun” turned up only this blog.
    Well played, B.B.! You had me going for a minute there! =)~

  7. You’d think this is an April Fool gag pic, but it is real. Practical? Not so much.

    You almost had me when you threw in the part about the sanctimonious faculty member…in Californian Academia, all loony things are possible.

  8. B.B.,

    Brilliant! You fooled me even though I knew what day it is! And thank you so very much for putting a smile on many faces this morning, mine included. I’ll bet you plan these installments months in advance, running ideas through your head now and then during the year, don’t you? :^)


    • Michael,

      How much hard currency equivalent are you drooling?
      I may be able to work something out on a low serial number First 100:. 10812002X

      It actually has figure in the Walnut Stock since it was selected for an INFLUENCER no doubt.


      • shootski,

        If my 401k hadn’t just tanked, I’d make an offer. As it is, however, I might have to look for where the bread lines are going to form. :^(


    • Michael,
      I didn’t have the “Star Trek” packaged gun, but I had several of these type guns as a kid. I loved them. Bought them at K-mart. We don’t even have K-mart anymore. 🙁
      Thanks for the memories


  9. We all needed this 🙂

    Whomever invented roundabouts should be used as a target at the next Frisbee gun accuracy competition or at the very least be given the Ig Nobel Prize in the category of engineering. Last years prize in engineering went to some iranian for inventing a diaper-changing machine for use on human infants.

  10. Embarrassingly this took me almost all morning to remember that BB *loves* writing tantalizing articles on April 1st!
    Tom, I swear every year your April 1st posts get better and better!

  11. B.B.
    Nice try. Praying on our gullibility? Just like our current leader. I am glad I dont need all new ammo tho.
    Hey, they parked a nuclear aircraft carrier in Guam because the crew is contaminated with C19.
    That is something.
    Be well

    • 1stblue,

      Come-on, you believe those Swabbies! They just wanted some shore leave to go Boonie Stomping in the island’s interior…Social Distancing at its best. Unless you choose to go SCUBA diving breathing that clean filtered air in that clear water all the way around Guam.

      I fact, I hope they get it under control soon. Then go on to learn and put in place methods for decontamination, set up their shifts, or set up A-B teams to keep at least essential crew available for duty and continued Full Cycle Operations.


      • Shootski
        You have a knack for bringing up a lot of Navy memories for me but you have outdone yourself today.

        A loadmaster admitting that we were just a bit over weight and we never really took off but simply ran out of runway and were a few feet over the ocean. A pathfinder/logistics mission to the far east in a DC-9 equipped with ‘extra belly fuel’ tanks.
        Then spending time at the ‘Guam’ Dai-ichi Hotel and finally F-14 ‘cyclic’ ops on board the USS Constellation.
        The worst of times and the best !
        Bob M

        • Bob M,

          You are most welcome Shipmate!
          I’ll bet we could spend months exchanging TRUE Stories and then years on Sea Story after Sea Story!
          I have some that In should record if only they could be declassified. I tried one time and after all the redactions it wasn’t a story anyone could understand or probably believe if i had fictionalized it!
          Stuff like substitution of Warm Southern Island for a real island name. I’m sure you probably have some from your comments.

          Stay well Shipmate!


      • Shootski,
        I think it is a very bad idea for the media to be broadcasting to the world information regarding our war ships! Is it important for everyone to know that there are confirmed cases of the Corona Virus on our ships, and what’s being done to mitigate it? I would think this would be a national security issue. The news media thinks that EVERYONE needs to know what is happening in our military…even our enemies. Bad idea.

        • Geo,

          Is there even such a thing as “secrets” these days? With the exception of some high level stuff,… I would bet that near every country knows what the other is doing,… especially ship location. Even without govt. acknowledgement,.. social media would have quickly filled in the blanks, be it here or there. Satellites. They can zoom right in on anything anymore.


        • Geo,

          I hope the Skipper’s “letter” (Message is the correct term) wasn’t Desperate! If it was he should be relieved for cause! If he leaked it to the media he, or whoever did should face a Courts Martial!


  12. B.B.

    You had me going until the pic of the target.

    There’s no way you wouldn’t have mentioned rotating the barrel (or was it the target?) 60 degrees between shots.


    (edited: You did mention it! But it was in the caption. And red. Great article!)

  13. I wonder how much brain power was wasted today before it was figured out. BB got me once before and I even asked something about it on the Yellow and got laughed off the page. Since then I have gotten better at sniffing these wild tales out.

    David Enoch

  14. I read this quickly while at work (yes we are considered essential personnel) and I read it with great interest.

    Then I saw the test target, and realized a photoshop job.

    And remembered the date.

    I am having a blonde day, running behind the curve so to speak…

    Happy April 1st everyone.

    Stay safe,


  15. BB,

    I think you have outdone yourself with this one. I feel that you really pulled off the old switch-er-oo and the consensus here is that this is the usual April Fool’s joke. I, of course, have figured out that it is, in fact, real, as witnessed by the opposition to the device’s submission for the award based on California consumer warning guidelines and moral positioning. That right there is real-world stuff!!!! Almost got me, you devil !!


  16. BB
    So as I’m reading I found myself wondering, why would someone invent something so totally useless and try to solve a problem that didn’t exist, considering the performance of the 338 Lapua Magnum. All the time trying to figure out a better way to utilize it. Tubular bullets with a sabot? Thinking of those tubular frisbees that go on and on. But what good would a tubular bullet be?
    So you had me. I never pay attention to the day of the week anymore, let alone the date. It’s there on the TV if I need it.
    April 1st is a very significant day in my life. It’s my wedding anniversary. A day that changed my life forever 51 years ago. Considering that I have been divorced for 41 years now it’s just an occasion to remind me of life back then and the fact that I’m still affected by it today. We currently share my home for a variety of reasons that convince me I made the right decision in ending it.
    Being a certified April Fool must make me more susceptible. 😉

  17. I am instructing my lawyer to file a patent infringement lawsuit against Thomas Manke for stealing the basic projectile stabilization system of my Poison Life Saber Air Gun. US Patent 007-2016 predates his invention and describes how a rifled rod can be used to stabilize rolls of cyanide laced Life Savers shooting through my selective fire PCP Life Saber Air Gun. These poison Life Savers are designed to embed in the target’s flesh and be absorbed into the blood stream without leaving a ballistically traceable projectile. The CIA, Seal Team Six and Delfa Force are currently field testing my prototypes.

    I believe I will prevail in this lawsuit which will lavishly reward me for damages. Those funds I will use to perfect the development of my Frozen Poison Gummi Bear Repeater Cross Bow for which I will also be starting a Go Fund Me website soon. So stay tuned to this blog!

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