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  1. #1
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    155mm M483A1 DPICM

    Cutaway model of a M483A1 DPICM (Dual Purpose Improved Conventional Munitions) projectile:

    Purpose of the projectile:
    The purpose of this projectile is to saturate an area with (M42/46) submunitions (also called bomblets), thereby creating a more controlled fragmentation over a larger area -when compared to the 155 mm M107 HE (DM21) projectile-, together with an armour piercing effect caused by the shaped charge.
    The projectile is meant to be used against uncovered personel, artillery positions, resupply points, and against lightly armoured vehicles. It is not meant as a replacement for the M107 HE, but as a supplement.
    The M42/46 bomblet will not knock out a main battle tank, but can severely damage parts like optics, the main weapon and other external parts of the tank, thereby effectively crippling the tank.

    Description of projectile M483A1:
    The body of the projectile is a steel -drawn and rolled- tube, threaded in top to receive the aluminium upper piece which is screwed into the body. The body is machined on the inside and three keyways -at 120 degrees each- are machined into the longitudal direction of the lower body. In the top of the lower body, the diameter becomes smaller to form the seat for a steel piston. The part above the piston, together with the aluminium upper cap forms the combustion chamber of the projectile.
    The piston is a flange which closely fits the inside of the lower projectile body. It has an O-ring on the outer rim to enshure a gas tight sealing between inner body and the piston.
    The lower part of the body has five windings of fine thread to receive the aluminium basecap, which has only four winding of thread. A rubber O-ring and a paste/glue between the thread enshure a gas tight seal beween body and basecap while travelling through the barrel.
    An aluminium hat with four longitudal weakenings at 90 degrees each containing the expelling charge is placed in the top of the upper (aluminium) piece. The upper rim of the hat is rolled outward to lock it into the upper piece. The powder for the expelling charge M10 powder and it is packed in a nylon bag. On top of this aluminium hat a steel filler disc is placed, locking up the powder charge. Screwing the fuze on the projectile locks up the ring.

    Functioning of the projectile:
    Before firing, the fuze is set on airburst on a point at approximately 300 mtrs above the ground.
    When the MT565 fuze ignites on the set time, the flame enters the detonator in the centrifugal safety element. The flame of the detonator ignites the powder of the expelling charge. The gasses rip open the aluminium hat over the four longitudal weakenings, filling the combustion chamber and starting to press upon the piston, up to a moment where the four windings of thread are ripped away and the cargo of 88 M42/M46 submunitions are dispersed (centrifugal force) from the base of the projectile. Depending upon the trajectory angle and speed, a round or an elipse shaped impact pattern of submunitions will occur.


    Submunition M42 / M46, description and functioning:
    The cargo of the 155mm M483A1 is made of 88 M42/M46 HEAT Frag (High Explosive Anti Tank Fragmentation)submunitions, placed in 8 columns of 11pcs. Seven columns in a circular pattern around one column in the center. The submunitions are placed cone forward, the impact fuze M233 of the submunition stored in the cone of the submunition below. On the outer circumference of the submunitions the space between the submunitions and the inner wall of the projectile is filled with triangular nylon filler pieces, tightly locking up the submunitions. Three of these outer rows of filler blocks are made of aluminium and have a key on the outside that fits into the three keyways in the inside of the body, preventing the cargo of submunitions from radial movement compared to the projectile body on firing. The central column submunitions are packed in two 5 mm thick nylon half pipe pieces that surround the submunition.

    The difference between the M42 and M46 submunitions is to be found in the body of the submunition. The body of the M42 is broached on the inside for improved fragmentation, the body of the M46 is smooth on the inside, making the submunition mechanicaly stronger. The cargo of a M483 shell exists of 64 M42 and 24 M46. The top submunition and the two lower submunitions in all columns are M46 shells. This is done to prevent the submunitions of being crushed on expulsion and the cargo getting stuck.
    The body houses a red copper 1mm thick cone with a 60 degree top angle. Projectiles are normally filled with RDX, however composition A5 has also been used. The weight of the explosive charge is 30,5 grams.
    The fuze used is the M233 impact fuze. This fuze is made up of seven parts : The pressed sheet aluminium fuze housing (1), the slider (2, houses the firing cap, yellow), the slider spring (not visable), the hammer piece (3), the firing pin (4), the ribbon (5), the ribbon keeper (6).
    On expelling, the airstream will rip the ribbon out of the ribbon keeper. The ribbon stretches out and starts to vibrate in the airstrean , unscrewing the firing pin from the hammer piece. A small flange just below the point of the firing pin falls into a recess in the hammer piece. In safe position , the point of the foring pin is placed in a hole in the slider, preventing the slider from moving outward aligning firing pin, firing cap and detonator. On impact , the firing pin moves downward together with the hammer piece into the firing cap, igniting the submunition.
    The lethal fragmentationradius is 5 mtrs. Penetration of the hollow charge is 3” (76,2 mm) of steel.
    The complete projectile with folded ribbon is 81 mm high, the body diameter is 38,5 mm.

    The grenades provide the projectile's dual capability. However, a third effect can be achieved by replacing the original expelling charge with a spotting charge designed to detonate the entire projectile as if it were a bulk-loaded HE item.

    Weight of complete projectile: 46,5 kg
    Length of projectile : 802 mm
    Length of fuzed projectile : 892 mm.
    Max range of the projectile : depending upon weapon from 14.320 up to 17.740 mtrs
    Vo: 660 mtrs/sec

    Three other types of submunitions are used in this type of 155mm projectile body; the submunition DM1348 (155 mm Granate Dm 602 & 612), the submunition DM1383 (155 mm granate DM642), and the submunition DM1385 (155 mm Granate DM632). The main difference between the submunitions is that the Dm1383 and DM1385 have a self destruct mechanism, the DM1384 has not. The fuze for the DM1383 is more or less like the M223 impact fuze, as used on the M42/M46 submunition.

    The submunition M42 is nearly the same as the submunition M77. However the M77 is used in the M26 MLRS rocket (644pcs/rocket). It has a lower airspeed after expulion and therefore has a wider ribbon.

    Weapons that use the M483A1 155mm projectile: M109, M109 A1/A2/A3, M198, M114/39

    Regards, DJH
    Looking for / Suche noch:
    -8,8cm Pzgr.40.
    -8,8cm D (drahtsperre)

  2. The Following 2 Users Say Thank You to pzgr40 For This Useful Post:

    917601 (21st March 2016), Slick (22nd March 2016)

  3. #2
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    Great section and great information, thanks for sharing that.
    Hope you don't mind me asking, how long did that take to do. It looks like months of hard work!!
    Dave.

  4. #3
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    You're welcome. A projectile like this costs me appr 100 hours to make. Time is devided over the weekend and some hours at nigt every day after working time.
    Looking for / Suche noch:
    -8,8cm Pzgr.40.
    -8,8cm D (drahtsperre)

  5. #4
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    Between 0:18 and 0:24 one can see the workings of a DPICM projectile; submunitions raining down.
    [ame="http://www.youtube.com/watch?v=S3oWY-Kxzx0&feature=related"]YouTube- US Army - Artillery barrage exploding[/ame]
    Regards , DJH
    Looking for / Suche noch:
    -8,8cm Pzgr.40.
    -8,8cm D (drahtsperre)

  6. #5
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    Found this at the local AN store, ( picked it up yesterday), it went unnoticed by me for a year due to all the junk piled around it. Pristine, but no lettering. Question, what year is it? I would think 1986? Stamping, " MCH 86L006-020 155MM M483A1". I suspect it is a later model, internet sources state the M483A1 was produced in the 70's, do you think the 86 denotes the year? It stands about 31 inches tall w/o fuze. From a collectors view, would the value be diminished if it was accurately lettered to TM specs? ...for interest, a good video...

    https://m.youtube.com/watch?v=IroOVamQZHQ
    Attached Images Attached Images
    Last edited by 917601; 21st March 2016 at 11:42 PM.

  7. #6
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    December of 86. We were making them at Norris Industries in Vernon California in 89 when I worked there. My mentor told me that a few years before that, when they were running overtime, that they produced 12,000 a month.

    You need a base for it.
    ___HAZ/
    _____/ORD Hazardous Ordnance Recognition
    ________Saving Lives Through Education

  8. The Following User Says Thank You to HAZORD For This Useful Post:

    917601 (22nd March 2016)

  9. #7
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    Quote Originally Posted by HAZORD View Post
    You need a base for it.
    You have the right time fuze standing behind it. So that problem is allready solved.
    By the way.... nice find.

    Regards, DJH

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    917601 (22nd March 2016)

  11. #8
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    Norris would sell each projectile to the government for around $250.00. The ogive and the base are aluminum forgings and were anodized before painting. The ogive screws into the main body and has a rubber O-ring at the joint to make sure it is sealed. Each projectile was air tested in a water tank for leaks before leaving the assembly line.

    The main body is a high carbon steel forging ironed to shape, with a fiberglass wrap around the middle portion. A machine would automatically wrap the projectile with fiberglass, and then grind the outer surface to the proper diameter and smoothness. The projectiles were carried to a robotic paint booth that would set the projectile on a rotating turntable, with the bottom part of the projectile where the rotating band is, shielded by sitting in a piece of pipe. The projectile was preheated in an oven, and then rotated as a paint sprayer would move up and down from top to bottom spraying for a fixed period of time. There was a waterfall behind the sprayer to catch all the fumes and overspray.

    The M483 projectile was used for a variety of cargos besides the Grenades shown in the sectioned round. It was also used to carry two types of RAAM antitank Mines (Long and Short delay self destruct times) and two types of ADAM antipersonnel mines (Long and short delay self destruct times).
    Last edited by HAZORD; 22nd March 2016 at 01:39 PM.
    ___HAZ/
    _____/ORD Hazardous Ordnance Recognition
    ________Saving Lives Through Education

  12. The Following 2 Users Say Thank You to HAZORD For This Useful Post:

    917601 (22nd March 2016), pzgr40 (5th March 2018)

  13. #9
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    Thanks for the detailed information. The fuze type noted, and installed. (MT XM 565). As for the lettering question, with the information supplied I will leave it " as is", a screw up on the rolled lettering would most likely require a complete redo on the original paint. I will be on the lookout for a base, and perhaps a few sub- munitions, unlikely found in my world. In any case, this upcoming weekend I will haul my collection to the CAF at Falcon Field for one of their events. The Commemorative Air Force membership is waning, ( they have sold off a few old warbirds recently) and they have planned a summer drive to rekindle interest and recruit new members-donations and appreciation has been dropping off, a sign of the times.
    Attached Images Attached Images

  14. #10
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    Quote Originally Posted by 917601 View Post
    . . . I will be on the lookout for a base, and perhaps a few sub- munitions, unlikely found in my world.
    Here's an official INERT M42 and an unfinished body. PM if interested.
    IMG_1722.jpgIMG_1723.jpgIMG_1724.jpg

 

 
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