An Introduction to MBA Gyrojets and Other Ordnance

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Gyrojets, Finjets, Lancejets, Javettes, less-lethal … Here you will find information describing the first-ever book about the miniature rockets invented by Robert Mainhardt and Arthur T. Biehl, Ph.D., in 1960 when they co-founded MBAssociates (MBA). “An Introduction to MBA Gyrojets and Other Ordnance,” by long-time Gyrojet researcher, historian, collector, and Mainhardt confidant Mel Carpenter, covers the development of Gyrojets, Finjets, Lancejets, Javettes, Flares, Less-Lethal ammunition, etc. and the experimental, prototype, test, and production firearms (some of which were unknown until now) and launchers – over 60 of them – that fired them.
Category: MRC3 Publishing


After nearly 10 years of research, including over 50 hours of face-to-face interviews of Robert Mainhardt and phone calls; interviews of MBA and other Mainhardt company employees; careful review of once-classified government and company publications, films, audio recordings, articles, U.S. Senate public hearings transcripts, correspondence, and contracts; plus close examination of thousands of miniature rocket specimens, firearms, and launchers, the story of these fascinating rocket weapon systems is finally being told, with many myths and other incorrect information about MBA’s firearms and rockets being set right.
The 8.5 x 11 inch spiral-bound book has 422 pages, 286 with color. There are 466 color and 279 B&W figures. All Gyrojets, Finjets, Lancejets, Javettes, and flares up to and including 40mm are shown at actual size, as are .38-caliber and 12-gauge less-lethal rounds. The book covers every known Gyrojet rocket ever made, from 2.8mm up to 55mm, plus the 0.030-inch Javettes for the “CIA Dart Gun” with their biological or chemical payloads.
Q: When you were talking to Bob Mainhardt, did he ever comment on the use of the word “Automatic” on the early cardboard pistol boxes? (Eric Davidson)
A: Yes, he did. The early boxes were designed specifically for the .49-caliber Model 137 pistol. The prototype Model 137 was made in “late 1962.” Production Model 137s would have started a little later, in early 1963. The date on the back of the boxes, 4-63, corresponds nicely with these dates.
As you know, Mainhardt never threw anything away that could possibly be used later. Lots of the Model 137 “Automatic, Rocketeer” boxes were made, but MBA did not sell anywhere near enough Model 137s to the U.S. military or anyone else to use up the boxes. So, when Mark Is were put in the market, and then the transition models with the first slide, and then the Mark I Model Bs, the old boxes were used to store and ship them. That’s why the cutout for the Model 137’s rear sighs does not match the slide-equipped pistols with their different sight radius..
The prototypes and first production models intended for the military were full-automatic, which is why the box says “Automatic,” even though MBA never sold any full-automatic pistol (or carbine) to anybody, including the military, according to Mainhardt.
Q: What started the whole less-lethal quest by MBA?
A: MBA’s interest in less-lethal weapons began in 1968. Gyrojet firearms and rocket sales were stagnant, and the Gun Control Act of 1968 had placed the entire Gyrojet line in jeopardy by classifying 13mm Gyrojet guns (but not flare launchers) as destructive devices. By 1968, MBA had built up a significant firearms and ammunition-manufacturing capability, and Mainhardt did not want it to go to waste as 13mm Gyrojet pistol and carbine production ended. The decision to begin 12mm Gyrojet pistol production on a limited scale had not yet been made. A new line of less-lethal (originally, and wrongly, called “non-lethal”) products could keep MBA’s tools, machines, and manufacturing personnel busy and hopefully make a profit for the company.
At the time, Robert C. Mawhinney was MBA’s Ordnance Systems Manager. Mainhardt tasked Mawhiney with finding out all he could about then-current, less-lethal weapons to see if any of them might be useful to MBA as new products. Mawhinney was surprised to discover that there were very few less-lethal weapons in existence, and that there was almost nothing in the literature about them. Most less-lethal weapons had been quickly developed, tested, and then dropped because they were not effective, too complex, too expensive, not reliable, or all of the above. After taking an inventory of the few products available in the market and evaluating each of them, Mawhinney began a study to determine what was required to inflict “extreme discomfort or incapacitation” on a person in order to stop him or change his behavior without killing him.
According to Mawhinney, in a moment of inspiration the solution “just kind of popped into my mind.” A heavy cloth bag filled with shot could be folded over and loaded in a conventional cartridge case. When fired through a rifled barrel, the bag—later named the “Stun-Bag”—would engage the barrel’s rifling, spin, and open up flat when clear of the muzzle due to centrifugal force. Because a very large bore was not required, the launcher could be of a manageable size and weight. In fact, the largest caliber used with the Stun-Bag was 40mm (1.57 inches). The projectile did not need to have a large diameter when it was fired. It just needed to have a large area when it impacted its target.
On Monday, May 4, 1970, following several days of campus unrest and antiwar demonstrations, four students at Kent State University in Kent, Ohio, were killed and nine others wounded by Ohio National Guard soldiers who were armed only with tear-gas grenades, issue firearms, and ball ammunition. The shootings by under-trained and over-equipped soldiers were extremely controversial, and resulted in antiwar demonstrations nationwide. During research for this book, I spoke with Alan Canfora, who was one of the students wounded that day—he was shot through the right wrist by a soldier firing an M1 Garand—and he was interested to learn that the shootings had been instrumental in motivating MBA to develop its less-lethal weapons.
This tragic event made a tremendous impression on Mainhardt, who became even more determined to provide the Army with a less-lethal option for crowd control. Shortly after Kent State, Mainhardt told Mawhinney to do everything he could to complete work on the Stun-Bag as soon as possible. MBA’s less-lethal development had a high priority, and Mainhardt gave Mawhinney a “blank check” for whatever he needed after an initial project funding of $10,000.
Q: What is a Gyrojet?
A: A Gyrojet is a miniature rocket that is gyroscopically stabilized in flight by spinning around its longitudinal axis, like an American football being passed. Gyrojet rockets range in size from 2.8mm up to 55mm, with 13mm being the size most often seen now. A Gyrojet’s spin is produced by its nozzle (base) ports (holes) being drilled or punched at an angle. Gyrojet rockets were normally made with copper-plated steel cases. “Gyrojet” is also the name of the firearms that fire Gyrojet rocket ammunition.
Q: How much are Gyrojets worth?
A: Gyrojets, like all collectibles, are worth what someone will pay for them; the amount of money that changes hands between a willing buyer and seller. For a collectible to have value, three things have to happen: 1) collectors must know that the collectible exists, 2) collectors must want to have it, and 3) the collectible must be available in limited quantities. The more collectors know about a collectible, the more they want it, and the scarcer it is, the higher the values will be. Until now, there was little information available about Gyrojets, etc., so there wasn’t much demand for the few specimens available. A “standard” 13mm Gyrojet rocket has a value of about $35 – 65 depending on condition. Same for 12mm versions. Other, scarcer calibers can easily bring $200 plus, and the WW II German 9mm “S_Patrone” rockets can top $1,200. Finjets are $200-250 because they are so rare, and Lancejets can be about the same. 13mm and 12mm Gyrojets (rockets and firearms) were the only calibers offered to the public, so other calibers are much scarcer.
Gyrojet firearms range from about $3000 for a cased Mark I Model B 13mm pistol in exc-mint condition to about $1,300 for a Mark II Model C 12mm pistol in its original cardboard box. Condition makes a tremendous difference in value. A mint condition Mark II Model C sold for $2,100 on September 12, 2010, at the Rock Island Auction.
If you have a specific example, I’ll be happy to estimate its value. I have about 500 entries in my database, all of which are actual prices realized at well-advertised, public auctions.
Q: Do I have to go through the U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) to obtain a Gyrojet firearm.
A: Probably not. Almost all Gyrojet firearms have been designated as Curios and Relics by ATF, and can be bought and sold like any other firearm. A Curios and Relics Federal Firearms License (C&R FFL) is very easy to get and renew, and makes collecting Gyrojet firearms a lot easier.
Q: What is a Finjet?
A: A Finjet is a miniature rocket aerodynamically stabilized in flight by fins, like an arrow. Finjets were MBA’s first product, and are typically 3mm in diameter. They were normally made of injection-molded plastic with steel points, or less-often of aluminum.
Q: What is a Lancejet?
A: A Lancejet is a miniature rocket stabilized in flight by mass being concentrated at the rocket’s nose, like a javelin. Lancejets are typically 1.5mm or 3mm in diameter with some anti-mine versions being 6.35mm. Lancejets often have aluminum bodies and steel noses. Lancejets were designed to be fired in salvos, although some larger underwater versions were single-shot.
Q: What is a Javette?
A: A Javette is a solid, unpowered, sub-miniature, ballistic projectile for use in antipersonnel operations. MBA Javettes were typically half the size of the smallest Lancejet. Some Javettes had threaded tails to hold a biological warfare (BW) or chemical warfare (CW) agent. 0.030-inch-diameter Javettes typically had tungsten noses and magnesium tails. They were fired from modified cartridges and firearms, often silenced.
Q: What does “MBA” stand for?
A: MBA is short for M (Mainhardt) B (Biehl) Associates, typically written with no spaces: “MBAssociates.” MBA was located on Bollinger Canyon road in San Ramon, California. The company was bought by Tracor, Inc. in 1980, and Mainhardt stayed as Tracor/MBA’s president until he left in 1982.
Q: Who was Robert Mainhardt?
A: Robert Mainhardt, 1922-2006, (no middle name) was one of the two co-founders of MBA in 1960. Arthur T. Biehl, PhD, 1924-1993, was the other co-founder who left the company in 1965.
Q: What does “less-lethal” mean?
A: “Less-Lethal” is term MBA used to describe a series of weapons designed to inflict non-fatal injuries on human targets such as rioters. However, if improperly used, a so-called “less-lethal” device can inflict fatal injury, so “less-lethal” does not mean “non-lethal.” MBA Stun-Guns and Prowler-Foulers are less-lethal devices.
Q: What is a “MIRA?”
A: A MIRA is a Dutch miniature rocket (Mini Raket) modeled after MBA Gyrojets, Finjets, and Lancejets.
Q: What is a Microjet?
A: “Microjet” is MBA’s designation for a group of miniature rockets including Gyrojets, Finjets, and Lancejets, but not Javettes, which had solid bodies.
Q: What was Trebor?
A: Trebor, Inc. was the company founded by Robert Mainhardt in January 1983 after he left Tracor/MBA. “Trebor” is Robert spelled backwards. Trebor concentrated on less-lethal products, and sold leftover inventory from MBA in addition to newly-manufactured items. Trebor filed for bankruptcy in July 1988.
Q: What was PSI?
A: PSI, Protection and Survival International, Inc., was the third company Robert Mainhardt founded, after MBA and Trebor. PSI was founded on September 3, 1991, in an attempt to sell off the remaining inventory of less-lethal devices and Gyrojets from MBA and Trebor. The company was in business for only about one year.
Q: What are “Swarmjets?”
A: Swarmjets are MBA kenetic-energy rockets designed to be fired in salvos to intercept and destroy incoming enemy ballistic missile atomic warheads.
Q: What is the largest Gyrojet?
A: The largest Gyrojet we know of is a 55mm Swarmjet, but only a drawing of this rocket is available. No specimen is known. The largest Gyrojet actually seen is a 40mm cloud-seeding rocket.
Foreward, x  
Introduction, xi  
Chapter 1. MBAssociates (MBA) Founders, 1  
Robert Mainhardt, 1  
Arthur T. Biehl, PhD, 6  
Chapter 2. Company History, 9  
The Early Years, 10  
A Private Corporation, 14  
A Public Corporation, 19  
Less-Lethal Development, 19  
Tracor, Inc. Buys MBA, 22  
Trebor, Inc., 23  
Protection and Survival International (PSI), Inc., 26  
Other Businesses, 27  
MBA Area Map, 28  
Chapter 3. Finjets, 29  
Solid Propellant, 30  
Grain Fabrication, 30  
Grain Configurations, 31  
Propellant Grain Tests, 32  
Nozzle Design and Fabrication, 32  
Fuse (Igniter) Development, 34  
Case Design and Fabrication, 36  
Finjet Launchers, 43  
Finjet Variations and Notes for Collectors, 48  
Chapter 4. Lancejets, 51  
Anti-Mine Lancejets, 51  
Underwater Lancejets, 53  
Other Lancejets, 58  
Chapter 5. Javettes, 61  
Javelin Stabilized Quiet Round, 61  
Ammunition Concealment Round, 66  
Meson/Tiger’s Claw, 68  
Trebor .22 Rimfire Adapter Cartridge, 68  
TANG, 75  
Chapter 6. Introduction to Gyrojets, 77  
Why Gyrojets, 77  
Gyrojet Rocket Components, 80  
Igniter, 80  
Case, 81  
Nozzle, 82  
Primer, 84  
Propellant, 85  
Sealer, 86  
Chapter 7. Early Gyrojet Development, 87  
The First Gyrojets, 87  
.16-Caliber Gyrojets, 89  
Chapter 8. .25-Caliber Gyrojets, 91  
Chapter 9. .30-Caliber Gyrojets, 95  
.30-Caliber Gyrojets, First Type, 95  
.30-Caliber Delay-Fuse Gyrojets, 97  
Mark I Development, 99  
Long-Delay Fuse Development, 101  
Mark II Development, 102  
Short-Delay Fuse Development, 103  
Other Delay-Fuse .30-Caliber Gyrojets, 104  
SUU-13/A Canister Development, 107  
Chapter 10. .45- and .48-Caliber Gyrojets, 109  
.48-Caliber Gyrojets, 110  
Chapter 11. .50-Caliber Gyrojets, 113  
.50-Caliber K.E. (Kinetic Energy) Gyrojets, 120  
.50-Caliber High Velocity Satellite Defense Gyrojets, 122  
Chapter 12. .49-Caliber Gyrojets, 123  
.49-Caliber Gyrojet Rockets, 125  
.49-Caliber Gyrojet Packaging, 130  
.49-Caliber Gyrojet Pistols, 131  
First Gyrojets in Vietnam, 136  
Chapter 13. 13mm Gyrojet Rockets, 141  
Mark I 13mm Gyrojets: First Generation, 143  
Mark II 13mm Gyrojets: Low Cost, 145  
Mark III 13mm Gyrojets: Low Dispersion, 147  
Mark IV 13mm Gyrojets: Low Cost, Low Dispersion, 147  
1965 ARPA Field Tests, 150  
13mm Standard Gyrojet, 151  
13mm Bundy-Tube Gyrojets, 152  
13mm Wadcutter Gyrojets, 154  
13mm Two-Port Nozzles, 155  
13mm Powder-Metal Nozzles, 157  
Long-Case 13mm Gyrojets, 159  
Miscellaneous 13mm Gyrojets, 163  
13mm Gyrojet Ammunition Boxes, 166  
Chapter 14. 13mm Gyrojet Firearms, 169  
13mm Mark I Cased Presentation Sets, 169  
13mm Mark I Model B Transition Pistols, 178  
13mm Mark I Model B Pistols, 180  
13mm Mark I Model B Cased Presentation Sets, 182  
13mm Mark I Model B Short-Barrel Pistols, 186  
13mm “Indigenous” Pistols, 190  
13mm Gyrojet Carbines, 192  
13mm Mark I Model B Transition Carbines, 195  
13mm Mark I Model B Military Carbines, 195  
13mm Mark I Model B Sporter Carbines, 196  
Chapter 15. 13mm Gyrojet Flares and Launchers, 199  
Pistol-Fired 1.4-Inch Flares, 200  
Launcher-Fired 2-Inch Flares, 201  
Late-Production 2-Inch Flares, 205  
Launchers and Kits, 210  
13mm Radar Chaff Flares, 217  
Chapter 16. 12mm Gyrojets, 219  
12mm Gyrojet Rockets, 221  
12mm Gyrojet Ammunition Boxes, 223  
12mm Gyrojet Firearms, 225  
Chapter 17. Large-Caliber Gyrojets, 229  
15mm Gyrojets, 230  
20mm Gyrojets, 230  
25mm Gyrojets, 237  
30mm Gyrojets, 240  
40mm Gyrojets, 250  
Chapter 18. 40mm Less-Lethal, Gunpowder Powered, 253  
Conceptual Design Preliminary tests, 256  
40mm Military Stun-Bag Launchers, 257  
Production 40mm Stun-Bag Ammunition, 258  
40mm Stun-Bag Cartridge Variations, 263  
40mm Police Stun-Bag Launchers, 268  
Chapter 19. 37mm Less-Lethal, Gunpowder Powered, 273  
Stinger-37 Adapter, 273  
Stinger-37 Ammunition, 274  
Chapter 20. 12 Gauge Less-Lethal, 279  
Stinger-Stik, 279  
Stinger-12 Adapters, 281  
Stinger-12 Ammunition, 283  
Stinger-12 Ammunition Boxes, 287  
Stinger-Stik and Stinger-12 Accessories,288  
Chapter 21. .38 Special Short Stop Ammunition, 289  
Ballistics and Accuracy, 290  
Cartridge Variations, 291  
Short Stop Packaging, 294  
Production Ends, 295
Chapter 22. Gas-Powered Less-Lethal, 297  
Prowler-Fouler, 297  
Prowler-Fouler Instructions, 302  
Prowler-Fouler Cartridge Components, 303  
Prowler-Fouler Cartridges, 309  
Prowler-Fouler Kits, 311  
Westun Negotiator and Arma 100, 313  
Negotiator/Arma 100 Cartridges, 314  
Prowlette, 316  
Prowlette Cartridges, 317  
Pocket Prowlette, 318  
Less-Lethal Carrying Cases, 322  
Chapter 23. MBA at the Movies, 323  
“You Only Live Twice,” 323  
“The Hunter,” 326  
“Collision Course,” 326  
Chapter 24. Miscellaneous MBA Ordnance, 327  
Infrared (IR) and Chaff Flares, 327  
Squibs, etc., 330  
Cold Smoke Markers, 332  
AN/ALE-38 Dispenser, 332  
MBA Factory Display Boards, 333  
Chapter 25. Foreign “Gyrojets,” 339  
British Hale Rockets, 339  
German 9mm S-Patrone Rockets, 340  
Dutch MIRA (MiniRaket), 348  
French Rockets, 359  
Czech Rockets, 363  
Chapter 26. Miscellaneous Notes by Chapter, 367  
Appendix 1. Glossary, 385  
Appendix 2. MBA Patents and Trademarks, 393  
Appendix 3. Handgun Instructions and Components, 395  
Bibliography, 401  
Index, 403
The new supplemental chapter 27 contains information not in hand when the book was published in October 2010. Please download and print the new chapter for inclusion in your book. After you have printed the chapter, you can take your printout to Staples, Office Depot, Kinko’s or another similar store to have the printed sheets punched with the spiral binding holes. You may want to take your book to show exactly how the sheets should be punched.
Then cut off one end of the black spiral binding where it is bent over (but not too much), unwind the spiral binding from the book, insert the new supplemental chapter between page 408 and the back cover, re-wind the spiral binding to include the new chapter, and then bend over the end of the binding to prevent it from unwinding.
In time, after several new free supplemental chapters have been added, the current spiral binding in your book will need to replaced with a larger piece. There is no copyright on chapter 27. Feel free to save the pdf file on your hard drive and share it with anyone, anywhere.
Supplemental Chapter 28 contains new information acquired after supplemental Chapter 27 was published here last year. Please download and print the new chapter to be added to your book. After you have printed the 46-page chapter, take it to Staples, Office Depot, Kinko’s, or other similar office supply store to have the printed sheets punched with the small spiral binding holes. You may want to take your book to show exactly how the sheets should be punched.
Because Chapters 27 and 28 are so large – 84 pages printed front and back on 42 sheets – the original 30mm black spiral binding is now too small to hold everything. It should be replaced with a 33mm spiral or larger. An alternative that does not require disassembling your book would be to just bind the two new chapters in an 8mm spiral. The Staples store here does that for less than $5, including a clear plastic cover and hard plastic back. While this separate binding was not my original intent in 2010, I had no idea that I would receive so much new information that would increase the size of the book by almost 21%.

Supplemental Chapter 29 contains new information acquired after supplemental Chapters 27 and 28 were published here last year. Please download and print the new chapter to be added to your book. After you have printed this new chapter, take it to Staples, Office Depot, Kinko’s, or other similar office supply store to have the printed sheets punched with the small spiral binding holes. You may want to take your book to show exactly how the sheets should be punched.

Chapter 29

This is a listing of all known (by me) Gyrojet firearms or other firearms owned by MBA during the Gyrojet era. The serial numbers and descriptive notes are based on guns in my collection and in the collections of others, where the data are verified. For other listings, original MBA photographs, online auction sites where Gyrojet serial numbers were included, MBA correspondence, and original MBA inventory sheets, a.k.a., “gun logs” were used.
“Butt numbers” on Model 137 pistols refer to the numbers stamped on the bottom of the pistols’ handles after the frames were removed from their die. These served as early serial numbers for Model 137 handguns. When some Model 137 pistols were converted to Mark I guns, the butt numbers were sometimes removed, but not always.
Determining total production of a particular model is difficult because some of the firearms were “spoiled” during manufacture and scrapped. The fact that the highest known Model 137 butt number is 144 does not necessarily mean that a minimum of 144 Model 137 pistols were finished and released for sale. MBA gun logs show a Mark II Model C 12mm pistol serial number 606, and the log shows several spoiled guns. An estimate that there were about 600 Mark II Model C pistols produced and released for sale is probably very accurate.
This listing represents about 25% of MBA production, so it’s significant but certainly not complete. Your help in adding to the list will be most welcome.

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