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PzGr40
22.07.2007, 04:21
The 30 x 210 catridge was developed during WWII for the German MK303, a AA gun intended to be fitted to the new Type XXI U-boat, however this development had not left the experimental stage before the end of the war. The MK303 was developed by the Czech Arms Factory in Brno with the assistance of Krieghoff, it was a gas operated weapon and belt fed. Ammunition for the experimental MK303 was probably only made for test firing, so no certain types are known.
However, post war Czech cannons Br-300 and Br-303 are described with a Vo of 1000m/s and 400rds./min.
The 30x210 cartridge is now used in the AAA gun M53 and in the self propelled version M53/59. The first is a towed gun, weighting 2100kg, with two 2370mm long barrels, rate of fire is 2 x 450rpm. The second is a armored version of the Praga V-3S 3ton truck, the twin barrel AAA gun mounted on top.
Maximum horizontal range is 9700m, vertical range is 6300m, HE-T shell is effective up to 2000m, the APIT shell up to 1000m, maximum chamber pressure is 3200kg/cm². The API-T shell is able to penetrate 45mm of RHA at 60°/600m or at 90°/1000m.
Ammunition is fed in 10 round charger clips, the self propelled gun has big 50 round boxes. Cartridge cases are of Zinc clad steel, are primed with a Z-1 primer screw and filled with 195g of nctp 3x1,25/3,5-KFL propellant powder. Driving bands are steel. The CZ 301A (or CZ 301) self destruction fuze detonates the shell with the V16 blasting cap after about 6600m. Tracer burns bright red for about 4 seconds.
These guns are also used widely in Yugoslavia, for example on the Yugoslav origin BOV-30 self propelled AA sytem that usesd two M53 cannons and on Czech built M53/59 self propelled AA sytems. The Czech guns are also in service in Romania, Vietnam, Angola and Libya.
Cartridges are packed in 40 rounds in boxes measuring 600x410x280mm, weighting 63kg. Ammunition is manufactured by the Czech Republic and Yugoslavia.
Czech ammunition used in the guns:

Type 1:
30x210 Drill cartridge, black plastic with a bronze nose and shellcase base.

Type 2 & 3:
The JFSv (Czech designation) or HEI-T, it weighs 435 grams and has a Vo. of 997 m/sec,
Projectiles filled with 36,5g A-IX-2, CZ301A self-destruction fuze. Earlier type with CZ301 fuze

Type 4:
The JPZSv or (API-T). It weighs 435 grams and has a Vo. of 997 m/sec.
This is the later long type of projectile, l=137mm, Magnesium incendiary in ballistic windshield, topped by wax, bottomed by cardboard washers, and a hardened steel AP core.

Source of text info: “The russian ammo pages”.

A posting about the original Gun , the BR-303 can be found here:
http://blazeold.ath.cx/viewtopic.php?t=3502&highlight=30x210

Regards, DJH

x
22.07.2007, 05:52
The #1 dummy is Yugoslav

pufik
24.07.2007, 13:01
PzGr40: ...hi I am a new member from the Czech Republic, I am looking for informations about czech ammo, especially fuzes. Can you tell me something about function of CZ301A fuze - I am only beginner...

Can I have one more question? Did you made these 3 cutaways? They are very nice... And very dangerous when cutting yellow one :)

Thanks

PzGr40
24.07.2007, 15:29
Hi Pufik , they are both self destruct fuzes: after firing the balls are thrown outward in the groove preventing the firing pin from moving down. Below that a rolled up spring starts to unwind enabeling the firing pin to move down on impact. The difference between the yellow and grey projectile fuze is that the yellow one has an extra set back sleeve around the coil that sets back on firing, so an extra safety. On impact the balls are hammered inward, pressing the firing pin into the detonator. If no impact occurs, there will be a moment where the force of the spring pushing downward is larger than the centrifugal force of the balls in the groove. the spring will force the balls inward and the firing pin into the detonator.

I made them myself. Of couce they were fully inert when I bought them......how else would I be able to write you this message.

Regards DJH

Nabob
24.07.2007, 23:27
Here are some pictures.
Source: Delostrelecke zapalovace (Artillery fuzes) Vagner, Sudicky, Martin 1984

1- body
2- closing screw
3- holding screw
4- combined blasting cap
5- needle
6- rammer
7- safety segments
8- safety band
9- membrane
10- pounder
11- pounder spring
12- balls
13- insert
14- inercia sleeve
15- spring safety

Nabob
25.07.2007, 23:54
Translation for the picture
HE-T, API-T + projectile of older model, TP-T

1.fuze 2.projectile body 3.inserts
4.HE 5.screw plug 6.inserts
7.spacer 8.driving band 9.tracer
10.cover 11. case 12.powder
13.tube of powder charge 14.black powder
15.lid 16.primer screw 17.coat (cap)
18.incendiary filler 19.parafin
20.core 21.inserts 22. inert fuze
23.inert mass

pufik
30.08.2007, 19:29
Hi, PzGr40,

I would like to ask you, how do you make so perfect cutaways? Are yours cutaways hand-made (handsaw, rasper, sandpaper etc) or machine-made (milling cutter)?

I am especially interested in AP projectiles cutaways. The core of AP projectile is very hard and is putted in soft steel container (jacket). When you start cutting, you can not know, how deep inside you should cut. Because even the core is very hard, when you cut into it, you damage (scribble over) the surface of core. But when I take a look at cores of yours cutaways, I see the surfaces of cores are perfect.

For example first ammo: 30x210 Czech M53 AAA cartridges.JPG

Sorry about my english...

Milo
04.09.2007, 20:14
Pufik: Hier ist Funktion des CZ 301 Zuenders nach Sudicky und Vagner tschechisch:

Milo
04.09.2007, 20:15
Und CZ 301A:

Milo
04.09.2007, 20:18
Schnittmodelle:

PzGr40
04.09.2007, 23:07
Hi Pufik, all my cutaways are hand-made (handsaw, rasper, sandpaper etc) up till appr. 40 mm dia. After that I use a big handgrinder and 16” rasps to cut ammo, my biggest a 500 pdr snakeye for a museum within 1 mm straight. The bigger an object, the less fine you polish/finnish the surface . A 500 pdr is just rasped with a 16” rasp, the last rasping session with just very light pressure so you get a fine and ungrooved pattern. Of cource a 7.92 mm bullet gets a polishing with a piece of P600 sandpaper.

”I am especially interested in AP projectiles cutaways. The core of AP projectile is very hard and is putted in soft steel container (jacket). When you start cutting, you can not know, how deep inside you should cut. Because even the core is very hard, when you cut into it, you damage (scribble over) the surface of core. But when I take a look at cores of yours cutaways, I see the surfaces of cores are perfect”

For a starter -but everybody will understand- ; you can only cut a piece when you are 100% shure it is completely empty. It is always handy to have a drawing to see what it looks on the inside and how deep to cut before you reach the penetrator. Also handy to see what the shape, packaging and colour of expl. Charges and propellant sticks/grains in a projectile are.
When I bought my shell it had a long sawslot (red line pict 1) one had made to remove the ballistic cap. Of cource worthless for the “normal” cartridge collector, however very nice for the cutaway collector.

Remove the cap, it will be dealt with later.
To cut you start by sawing cuts A&B (pict1) untill your sawblade glides over the penetrator. Cut lines C&D until the saw glides over the lower edge of the penetrator on the one side, and just not touches the wall opposite wall of the tracer hole on the other side. You have just used up four sawblades.
Saw a wedge i.w.o. the base of the penetrator. Now start bending the upper piece of the projectile body up and down until it breaks off (mostly in appr 10 times up and down).
Now take a high speed rotary tool , something like this:
http://www.dremeleurope.com/dremelocs-uk/Product.jsp;jsessionid=EED9A404744F1413AC734374E0E B3E82?&ccat_id=674&prod_id=298
and start by machining away the hatched material (pict3 aft view) and made black (pict 3 top view), untill appr a 6x6mm square of the base of the penetrator is completely free.
No place the projectile on a piece of pipe that fits the upper rim of the projectile, and place it under a hydraulic press. Use a square piece of brass or bronze to press the core out.
Important note: one should UNDER NO CIRCUMSTANCE TRY TO HAMMER the penetrator out. You take a 90% risk of breaking your valuable penetrator, and chips flying off are sharp as a razor.
Put a piece of hard wood below the pipe to prevent the penetrator from falling on the steel baseplate of the workshop press if it is pressed out; it would not be the first time a penetrators point chips off on falling on a hard object (Pict 4)
Now the core is out, saw /rasp away the remainder and start to rasp the projectile into shape. Use a carpenters hook (90 degree) and a flat surface to determine if you are straight. On the last round of rasping , you place back the cap and rasp it , using the projectile body as guidance.
Press back the core, place the cartboard discs around the penetrator, place the cap. Before placing the cap, brush some grease on the penetrator (all around ) , the inside of the cap and the top cartboard ring. Fill the space with polyester resign (for car repair -cheapest-). When hardened take the whole stuff apart, remove the core, use gasoline to remove the grease and glue the risign mould into the cap. Now rasp the resign into the same 90 degr. angle as the rest of the projectile. You may have to fill the small air bubble holes on the surface of your cutaway, so three to four times small polyester mixing is normal.
Before finally assembling the whole lot, take a P80 piece of tape sandpaper , fold it over your rasp and gently po;lish the surface for a last time. After this , do not touch the surface again as even the slightest touch of a fingertip will be visable under your layer of clear varnish later as this nice brown fingerprint. Use a pair of thin rubber gloves as you place the penetrator, place the cartboard rings and the cap with the fake incendiary charge. Paint the surface of the “polyester incendiary charge” before placing the cap.
If there is scribbeling of the saw over the penetrator, place it with the damaged side to the back.

After assembly –still having not touched the cutaway surfaces with bare hands- you spray two (at least) to three (maximum) layers of clear varnish. Read the spraycan for spraying intervals.

Sorry about my english...

It’s not that bad either Babelfish translator has drastically improved since last week. :mrgreen:

Regards DJH

pufik
05.09.2007, 15:49
Wow, thats very nice and detailed description of cutting... Now I will translate it and read it up :)

Regards Pufik.