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MBA Gyrojet Mark 1 Model B Carbine notes (wow!!!)

mrmike08075
MBA Gyrojet Mark 1 Model B Carbine notes

I was digging through some storage chests and treasure boxes and came up with a number of really neat and rare objects (which I will post some data on later) including my original notes and observations from test firing and cleaning up one of these carbines in 2005

They are rough preliminary notes and observations but I thought some of you would find them interesting

If so please let me know here and I will post up some of my short hand range testing and research data

Mike
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Comments

19 comments

Date Votes
  • mrmike08075
    From my notes:

    The brushed chrome finish carbine I handled was one of the guns used in the AAI project test trials so I assume it to was an early piece
    Continuously spin stabilized projectile / rocket round (counter clockwise rotation) (no fins)

    I tried to chronograph the projectile / rocket but it turned into a complete failure on my end - the projectile (I will refer to it as a projectile though I am uncertain that's the correct technical nomenclature)

    When the projectile left the muzzle (a non rifled smooth bore launch tube - but I will call it a bbl) it clocked between 150 and 250 fps but that's not particularly useful data as unlike a normal firearm projectile with is spun up by the rifling in the bbl and loses speed after it exits the muzzle the gyrojet ammo appears to have a second phase boost stage that lights off at approximately 7 yds downrange and initially appears to accelerate as it moves towards the target

    I only have one chronograph and normal set it up just forward of a test guns muzzle - which does not provide an accurate measure of projectile peak velocity as it speeds up as it hits the 7 yd mark

    I believe to get good / correct data you would need 3 chronographs optimally positioned at the muzzle and again at the 7 yd mark and again just in front of the target

    And it's highly probable that I would hit the second and third farthest chronograph and destroy it - as I did not have consistent accuracy with the 40-50 year old factory produced ammo I used

    The ammo I used was 13mm approximately .51 caliber / diameter that came from the factory in sealed 24 round boxes (the carbine had a fixed 6 round integral magazine that was loaded from the action top like a C96 Mauser pistol)

    The ammo was early production "Mark 1" style with 4 rocket ports at the base (at 90 degrees from each other surrounding the primer) that were hand drilled in the base on a special drill press and lathe combo device

    A zinc chromate case that looks like brass - and the rocket ports were air / water sealed with red proprietary "humaseal" coating material - later ammo had only 2 rocket ports as a cost saving measure as hand drilling the ports on the drill press lathe required a skilled expert machinist and took quite some time - bases were often ruined during production and the specially hardened drill bits often broken or snapped off

    Ammo was literally hand produced with several assembly and manufacturing steps all requiring a special tool and a skilled patient machinist with much attention payed to quality control

    The action is a backwards / reversed delayed type - the hammer is at the breech and strikes the nose / front of the projectile pushing it back into a fixed firing pin / striker that ignites the primer

    The action is delayed by a split second - allowing the hammer to continue to move downwards and clear the breech

    The safety was two position and marked "On" and "Off" and I think it's a simple blocking device to prevent operation

    I believe the gun was an early scoped sporter carbine and not one of the bright shiny display guns - collectors cased pieces

    The gun had almost no recoil or muzzle rise - and was quite quiet - like a .22 air gun going off at ignition and with a bottle rocket like whooshing as it travels down range - the lit outlet ports are noticeably bright as the round leaves the gun - and gets much brighter at the secondary boost phase / 7 yd mark (does not stay bright very long)

    As the projectile is moving relatively slowly you seem to have lots of time to observe it as it travels toward the target

    The scope was a low powered small objective metal tube weaver - a rimfire rifle scope

    Two of the rounds I fired did not perform right - ignite right - burn right - or second stage boost correctly / probably due to age and storage conditions

    At 20 yds I achieved a group of around 10"'s

    I fired several additional rounds at 50 yds and achieved a group of around 12"'s

    Further testing was not conducted as my ammo supply was limited to one box of 24 rounds

    I would call the carbine an interesting expensive rare oddball toy

    I am uncertain of the results of the AAI project test trials and whether further modified or improved examples were provided to the army ordnance folks - or what other guns were submitted by other competing manufacturers - though I believe Daisy submitted a vvl careless ammo semiautomatic carbine

    Trigger was not a great design - should have been better

    Magazine capacity and having to hand load the fixed Mag from the top down with an open action one round at a time probably did not meet military specs - and could not be fed from a stripper clip - no stripper clip relief cuts in the gun to facilitate reloading

    Should have been a double stack high cap wide body detachable magazine

    I hope somebody finds these notes and observations useful or helpful

    Mike
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  • mrmike08075
    Side note - Ronald Reagan was a fan and had a cased pair of matched pistol and carbine

    Greatguns - please comment on and correct or critique my finding - opine on what I noted as you have much more first hand expert knowledge and experience on MBA - information that I was not even tangentially aware of and is not in any of my reference books - and is probably more accurate that my lore / tale

    That way no-one will be misled by my data and findings

    Mike
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  • mrmike08075
    And why did the discussions between them and Rohm and Haas not come to fruition???

    Mike
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  • mrmike08075
    Bump - btt

    Mike
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  • mrmike08075
    Thank you for backhand acknowledgment on my gun lore rock god status and reaffirming me as still relevant...

    Other than you and me my elderly father may be the only living human beings who are aware of what went on behind the scenes between your father and MBA and R&H chemical

    At the time it took place and the AAI program swept in and took control of some samples and testing the govt. Declared the data top-secret information (long since declassified I hope or we are now going to federal prison)

    My father worked at R&H in center city Philly then but also spent a lot of time at the springhouse PA testing facility

    He had a degree in chemistry and was in the army reserves and later national guard (R&H kept him employed and on the books and in the loop when he was on active duty with primary MOS of infantry and then later Military Police)

    My dad was very close friends with some of the science geeks who worked at springhouse - and because they new he was an army vet now in the reserves with top secret clearance and an active reservist and shooting aficionado / expert they roped him into some development and testing activities

    If I was a guessing man and thought myself some kind of expert I would opine that the acrylic material used to encase your samples was made / done by R&H and contained or was a precursor to roplex and R&H development of clear acrylic ballistic resistant materials ("bullet proof glass" for lack of a better term)

    My father and I have small presentation samples of .44 magnum handgun rounds imbedded in but not having penetrated or fractured the sample material ("do you feel lucky punk" - the most powerful handgun in the world)

    Maybe as we speak security personel from DOW chemical have contacted the federal authorities so we can be taken into custody

    For the GB forum member who privately emailed me and claimed I stole this data from an online video produced by Ian at RIA go suck eggs - I guarantee Ian does not know about what he have talked about here (BTW Ian is a great guy and RIA is good people IMHO)

    I was really quite bent by that accusation email claiming I should be banned from here for stealing someone else's work and claiming to have actually done this stuff...

    You have made me smile and the back and forth banter of information has engaged my brain and made me feel relevant again and welcomed here

    I hope that some few experts or owners or writers and researchers will find this thread chock full of info and as filling in the blanks from behind the scene first person observers and hands on shooters - and that some here or out in the world will also get something out of it and smile as questions long unanswered are now closer to being solved or clarified

    Seriously you have made my day - which has been a difficult one

    I do wish some members would ask additional questions or provide some of their own expert input or testimonial data

    Or comment on whether this has proved interesting on some level

    I think that you and Ian may be the experts on this canon and lore - I hope that I have added to it - or brought you some fond memories

    Thank you greatly for replying to this thread - please continue to add to it so that it's not lost data but known history

    You should write a book or magazine - journel article

    Best regards and much thanks

    Mike
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  • mrmike08075
    BTW - somebody please email Ian at RIA and send him a link to this thread...

    I don't have many contacts left at RIA and while I was introduced to Ian once back in the day while helping dispose of the perfido Diaz president of Mexico owned handgun collection but I doubt he remembers me or knows who I am

    Perhaps he may be able to use this data to greater refine his research or be able to contact the true expert (not me by any means)

    And thanks to those here who tolerate me

    Mike
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  • mrmike08075
    Greatguns,

    I spoke to my father about this thread today

    He believes that he has some patent documents amongst his shooting ephemera that are connected to this topic

    I will try to dig them out and see who's patents they are - ie which company held or filed for them

    I will try to determine if your fathers company or MBA are mentioned

    One more piece to the puzzle

    I thought you might be interested especially if you father or his company or MBA is mentioned

    And at this time I am not certain what materials the patent covers though I suspect you have hit the nail on the head and that you might already know

    Mike
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  • Mercury
    AWESOME thread guys! I'm a Gyrojet nut from WAY back.......I have a pistol, and a carbine! If you look on the wikipedia site, those are MY GUNS in the picture there! [:D]

    The guy I bought them from took pictures before he sold them, and somehow that picture is the "default" picture you see all over now, when talking about Gyrojets!

    Merc
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  • mrmike08075
    No shhit and no lie...

    I learned to work a Thompson trigger by a true artist and combat vet that they called "Korean Bob" when I was a young man

    The very first time I handled or fired a select fire or full auto weapon

    By the time we were done I could get controllable 2 and 3 and 5 round bursts out of a Tommy gun with a gangster style 50 round drum magazine

    My mom was so angry as despite hearing protection precautions I walked around for days not being able to hear with a ringing in my ears going "what???"...

    And it always struck a chord with me / stayed with me

    Bob using terms like work that gun and stroke that trigger - the far away look he would get on his face and the pauses in conversations were for a brief moment he was no longer with you but back in Korea with his service buddies fighting off human wave attacks of chicom soldiers during the retreat / backwards advance of the frozen chosen and the Pennsylvania national guard bloody bucket brigade

    Staking up the frozen dead like cordwood into trucks - never leave one of your guys behind even the dead - the unbreakable social contract that startled the hell out of the Chinese troops and often resulted in several additional dead / wounded to recover or refuse to leave one body

    Gave me nightmare dreams and disturbed my sleep as a kid - my first experience with what that would later call the thousand yard stare

    I believe to this day his unit holds the distinction of the only army unit to be displayed via a battle / honor ribbon on a USMC flag or authorized to were a USMC patch on their uniform on the off shoulder

    They are all gone now - aren't they...

    Great memories - on the gyrojet carbine and on learning to work a Chicago typewriter or on thoughts of caseless ammo development

    Thank you so much

    Mike
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  • T Ruth Hertz
    mrmike
    strange small world about Korean Bob
    my Uncle , who was a "Frozen Chosin" - spoke of a
    man who could make a Thompson sing and dance
    He was very proud of his army detachment and yes you are
    right about the USMC patch on his army uniform
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  • mrmike08075
    Someone sent me the online link to the YouTube episodic video series done by Ian at RIA - including the one on the gyrojet carbine...

    Fess up - that's one of you two in the video on the range with Ian...

    I found his video and data fascinating - it dovetails neatly with my personal experience and posted remarks (and OK it does bare a resemblance to what I posted or what you guys may have experienced - though it never occurred to me to test out body armor or use a ballistic dummy

    I did fire test ammo at rail road ties and phone poles and steel plate back in the day - and as a high school senior taking Mr. Taylor's AP Physics class in delran highschool I tried to build and test a ballistic pendulum as my seniors thesis project (1/4 of a semesters total grade)

    You guys fascinate me and take it to the next level - leaving me left in the dust with a boy like wonder look stuck on my face

    My father thinks he may have some careless ammo development documents from that time frame - I will investigate and keep you informed

    Here I thought I was maybe one of the last guys left with first hand experience and you two absolutely surpass and destroy my measly one box of ammo amateur investigations and experiments

    And for those of you whom have been supportive and sent private emails of encouragement - perhaps you are correct...

    It's not showing off or grandstanding - it's posting up some of the data and experience I was lucky to have so others may enjoy and it does not get lost to history when cancer kills me

    Who knew that you were hiding this from me for so long [:)]

    Mike
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  • mrmike08075
    quote:Originally posted by T Ruth Hertz
    mrmike
    strange small world about Korean Bob
    my Uncle , who was a "Frozen Chosin" - spoke of a
    man who could make a Thompson sing and dance
    He was very proud of his army detachment and yes you are
    right about the USMC patch on his army uniform



    Bob always opined that you needed a cutts compensator to make one cry and sing as Mark knopfler would say in sultans of swing...

    Bob would come into to the gun shop with Andre the giant back in the day...

    Thanks - your comments make me believe that perhaps I have it right and that the expert who taught me learned it right himself from some grizzled gunny or drill sgt

    The weight of the full drum Mag provided true controllable balance to the pistol gripped - no shoulder stocked variant of the Tommy gun but you had to be cautious as that weight rapidly disappeared as you ran through the Mag and muzzle climb increased

    I suspect that working the gun and stroking the trigger in short bursts by a true artist kept the bbl from overheating and from ammo cooking off prematurely and greatly sustained your rate of fire and the life of the gun

    I love this place somedays

    Mike
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  • mrmike08075
    And for the private emailed - yes you are correct...

    In Bob carpenters The Thing on screen in several scenes in the background are several drums and cartons prominently labeled Rohm & Haas

    God only knows were they came from or what they were supposed to contain

    Mike
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  • mrmike08075
    I response to additional private email inquiries from those with my email addy - or those having researched and found my addy here

    Yes you are correct in noting that there is no extractor or ejector function to the gyrojet guns from MBA as there is no case or cartridge component requiring further extraction...

    I could be a better author or aurator.

    I simply thought it was obvious to others that in this case the entire GYROJET / MBA rounds are single piece self contained rocket rounds that travel down the bbl intact and whole in one piece as it moves downrange

    I don't think it classifies quite rightly as careless ammo in the traditional sense like daisies smallbore vvl carbine design or H&K's later G11 careless rifle ammo attempts

    For those not aware I apologize and should have made that clear

    In the case of what I think of as careless ammo which has achieved some success or notaries and achieved high enough production numbers and success to be viable or limitedly commercially available

    I simply assumed that it was understood or implied - as I have fired a Daisy caseless carbine and handled a G11 and possess single collectors examples of both rounds

    They are self contained shorter "rounds" with no true discarding separate case constituent element or component - but instead having the powder or accelerate formed around the bullet in solid form and electrical or striker ignited

    And not traditionally shaped and often not round but squared off to optimize for feeding from high cap mags sometimes at right angles or 90 degrees from the receiver

    This nitro cellulose like formed shell serves as a bullet encasement and is burned up in the bbl and leaves no case or separate element to be ejected or extracted

    Can I have some help here from Mark Christian or nononsense in describing this right???

    Unlike but similar to these the gyrojet rocket all travels down the launch tube as the internal propellant is internally encapsulated inside and travels with things fueling them after leaving the muzzle and traveling on towards the point of impact

    I feel I don't have the correct terminology and am confusing the issue - GB forum experts please help

    And private mailers please post up here in this thread - others would like to hear your questions and thoughts and input

    Mike
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  • mrmike08075
    quote:Originally posted by GreatGuns
    quote:Originally posted by Mercury
    AWESOME thread guys! I'm a Gyrojet nut from WAY back.......I have a pistol, and a carbine! If you look on the wikipedia site, those are MY GUNS in the picture there! [:D]

    The guy I bought them from took pictures before he sold them, and somehow that picture is the "default" picture you see all over now, when talking about Gyrojets!

    Mercb


    Very cool. I may have the wrong image, as these are from the National Firearms Museum.

    https://upload.wikimedia.org/wikipedia/commons/a/ab/Gyrojet_at_National_Firearms_Museum_(460776909).jpg

    I have the model on top, one of the first 10 made. The other on the bottom is the full auto version I mentioned above. Only two were made, the one in the museum and the one in Bob's family's possession. I wish I had that one too. [^]





    Amazing pics and data - I had no idea...

    The carbine I handled and fired / as I refer to as a commercial carbine is identical to the top gun pictured except for the scope being mounted

    I did not even know that the second variant pictured existed with its obvious military design advanced and enhancement - with the carry handle aka armalite design

    Truly amazing

    I am stunned - is there a definitive book or reference work containing this stuff???

    Mike
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  • mrmike08075
    And no...

    I cannot answer why the gyrojet ammo I tested and those I have seen tested online now all seem to rotate / spin in a counter clockwise direction as they travel down range toward a target

    The bbl / rocket tube has no rifling - so no twist direction bias should occur

    And since all the examples I have experience with or seen are the 4 nozzles evenly spaced around the primer / striker on the base at 90 degrees of even separation that should not introduce a directional rotation bias - as they appear to all fire and be fed propellant simultaneously and equally

    I can provide no reasonable explanation - perhaps one of the other gents / experts can or will opine

    Never thought of that one

    Mike
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  • mrmike08075
    One more btt on a Friday for those who might have missed it...

    Mike
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  • Mercury
    The pistol (loose) and the top carbine pictured are what I own:

    https://upload.wikimedia.org/wikipedia/commons/0/0a/Gyrogroup.jpg


    I cannot remember the guy's name that I bought them from, but that was his picture, before he sold them to me. He emailed that picture to me after I took possession of them.


    Merc


    quote:Originally posted by GreatGuns
    quote:Originally posted by Mercury
    AWESOME thread guys! I'm a Gyrojet nut from WAY back.......I have a pistol, and a carbine! If you look on the wikipedia site, those are MY GUNS in the picture there! [:D]

    The guy I bought them from took pictures before he sold them, and somehow that picture is the "default" picture you see all over now, when talking about Gyrojets!

    Merc


    Very cool. I may have the wrong image, as these are from the National Firearms Museum.

    https://upload.wikimedia.org/wikipedia/commons/a/ab/Gyrojet_at_National_Firearms_Museum_(460776909).jpg

    I have the model on top, one of the first 10 made. The other on the bottom is the full auto version I mentioned above. Only two were made, the one in the museum and the one in Bob's family's possession. I wish I had that one too. [^]
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  • mrmike08075
    Wow

    Again the top sporter model carbine is identical to the one I tested except for a different scope...

    And the box of ammo pictured is what I used almost an exact copy

    You guys are great assets

    Mike
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