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.

Find a Hawke Scope

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.