CMFB patch released

NUTTERNAME

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Yeah, I read the thread and saw that it was labeled FlaK 18 and figured you might fall for it. That shell case is way too short for a 88mm.

I read your 50mm page. I think you are mixing up velocity with range. That is, up to 800 meters or so, the capped 50mm is better, and then it falls off due to the aerodynamics. And really, most of these 50mmL60 weapons were losing it beyond 800 meters anyway.

Of course, there is a capped version? PzGr 42?

View attachment 54143
 

mOBIUS

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There is a ballistic capped version but I have no data for it. The two versions ogive and capped I have only differ in penetration by 2-4mm vs. homogeneous armor.
If you want to see what the difference in ballistic capped vs ogive or chisle cap velocity vs range looks at the the velocity curve of the German 50mm pzgr 39 in http://www.lexpev.nl/downloads/handbuchderflugzeugbordwaffenmunition19361945.pdf
and compare that to the US 57mm APCBC velocity to range graph.
 

mOBIUS

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Per the penetration graph on my website. Where the blue line of the 50mm pzgr 39 crosses the pzgr Gr is about the 660m/s mark. On the Munition table above it this is near the 700m range (659m/s). When the velocity is lower, thus range longer the penetration of the pzgr G. would be higher. At least if that graph is to be believed. And the pzgr 39 doesn't have a ballistic cap. The AP cap should not be as aerodynamic as the older shell's ogive shape.

I think there is some pdf that gives a ballistic table/graph or at least drag factors for older US 37mm shells. The M59 would be similar to the pzgr 39 while the M80 (or M74) would be more like the pzgr Gr. The M59 ballistic coefficient would be .666. The M80 b.c. .777 (M74 .774) on the G1 scale.
 
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NUTTERNAME

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Per the penetration graph on my website. Where the blue line of the 50mm pzgr 39 crosses the pzgr Gr is about the 660m/s mark. On the Munition table above it this is near the 700m range (659m/s). When the velocity is lower, thus range longer the penetration of the pzgr G. would be higher. At least if that graph is to be believed. And the pzgr 39 doesn't have a ballistic cap. The AP cap should not be as aerodynamic as the older shell's ogive shape.
Yes, that is pretty much what I said. Most accounts I have read show that Panzer III crews were aware that they had very little chance outside of 500 meters (T34). And that is the L60 weapon using any ammo. North Afrika may have been different, but by 1943, the 5,0 cm weapons were outdated in the arms race. About the best chance a L60 had was to use its fast firing and accuracy to target the turret and specifically the gun itself. Likewise, the driver's hatch was within the accuracy limits of the weapon and could possibly get a result.

The chart is deceptive since the 'blue line' is not extended up to the muzzle velocity or matching the red line velocity. For the case of the L42 gun, and armored targets matching the chart, it might be a case of it not mattering what they fired, unless attacking a AFV with face hardened armor. Note that the region of the chart shows two hardnesses but they are fairly close.

I believe that the 5,0 cm projectiles were first monobloc (APHE) penetrators, two part (welded) 'monobloc' shaped penetrators, perhaps capped versions of the previous two, and finally a '42' version that was APCBC. All had a rather 'large' HE cavity given th actual size of the projectile. same payload as a 7,5 cm PzGr 39.
 
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NUTTERNAME

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An interesting artifact...I would think this means that the powder was made in the middle of 43 and it was bagged in january 44....I found a nice German document from April 1944...It has great stuff in it...

View attachment 54153
 

NUTTERNAME

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This is what shows as 'On the books' as far as ammunition in April 1944 for the Pak 38 and KWK 39 "L60" guns. The APHE and APCHE are there but no BC. Also, two AP40 with different powder weights. The 5cm stick grenade makes it!

View attachment 54154

These numbers are from Dec 1942 as far as ammunition stocks on hand


50 mm x 1000 rounds
Sprgr Patr 38 (5 cm Kw K): 1975.4
Pzgr Patr (5 cm Kw K) and Pzgr Patr 39 (5 cm Kw K): 1950.1
Pzgr Patr 40 (5 cm Kw K): 416.3

Sprgr Patr 38 (5 cm Kw K 39 L/60): 835.2
Pzgr Patr 39 (5 cm Kw K 39 L/60): 960.7
Pzgr Patr 40 (5 cm Kw K 39 L/60): 58.4

5 cm Sprgr Patr 38 (Pak 38): 1093.7
5 cm Pzgr Patr (Pak 38) and 5 cm Pzgr Patr 39 (Pak 38): 1627.3
5 cm Pzgr Patr 40 (Pak 38): 383.4
5 cm Stielgr 42: 0
 
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NUTTERNAME

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The document shows that the PzGr and PzGr 39 for the 5cm L60 cartridge (KWK 39 and Pak 38) has the same powder weight. If the PzGr 39 has a cap, and that adds weight...the velocities would be different, but the dimensions are different! The actual height on the 'bolt' or uncapped part of the PzGr 39 is smaller than the 'plain' PzGr and PzGr V (both uncapped). Both projectiles are listed as 2.06 Kg. makes sense or the sights would be off. It would seem these two cartridges lived side by side and I do not get the impression that the PzGr 39 was meant as a complete replacement.

The L42 gun was certainly pulled off the line and maybe there were some in 2nd line positions and training units. I was sort of befuddled to see a 5,0 cm KWK 40 listed in the document. I then realized that these were actually the L42 guns used in fixed coastal positions etc.

The document is basically concerned with explosive weights. This includes the HE and gunpowder weights. Wasn't there some debate regarding a certain 7,5 cm german weapon? Something to do with velocities and powder weights????
 
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NUTTERNAME

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They have two types of pzgr 40 for the 50mm/L60?
They have two types of PzGr 40 for the Pak 38. I would assume that the larger capacity version, shared between the Panzer III L/60 and Pak 38, was a later version but the Germans kept the earlier version 'on the books' because they had stock.

Do you have a copy of this document?

Edit: The Panzer III was probably percussion fired, so it might be that the ammunition was shared. But the document listed it as Pak 38...in any case, it is worth a look to see what velocity numbers might be for the two types of APCR?

Oh LOOK! They have numbers for 7,5 cm KWK 40 and also 7,5 cm Pak 40!
 
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I know they had more than one type of pzgr 40 for the L60 but I didn't know they identified them as such. What is the tank crew suppose to do about them? For that matter it would be confusing for a gamer as well.
 

NUTTERNAME

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they just have to read?

http://www.network54.com/Forum/47207/thread/1450506373/last-1450741895/View+Thread

This shows the different weapons that can fire it...as an example

http://www.history.jp/images/D435.1-Pak38.97-de.jpg

A good example is the KWK 40 cartridges that call out StuK 40 also. That means any KWK 40 L43 or L48 or StuK 40 L43 and L48 weapon would use that ammo. In the case of other 'L48' weapons (Hetzer or JgdPzr IV), the ammunition could come with a pamphlet that has the addendum. So much ammo is produced and it takes awhile for it to get to the end user. Weapons might be introduced and the plant would have to adjust the stencils/documentation for these weapons.

I believe that Allied intel would get wind of the ammo types from the documentation that they ship with. That is, they might report that a new APCR round is available for an enemy weapon, but they have not actually captured any yet. I believe this was the case for Pak 40 APCR in some US documents.

In the case of the 'two' Pzgr 40 rounds for the 5,0 cm L60 weapon, the only difference appears to be the powder type. That is, the weight is different but they are the same as far as performance. In the 7,5 cm weapon class, this is common for HE and HEAT and Smoke ammo to have two different types of propellant listed. But it is not used for the PzGr 39 or PzGr 40 ammunition for 7,5 cm weapons like the Pak 40 and KWK 40. That is, there are just one weight listed, an example would be Pak 40, PzGr 39 2.73 kg.

Basically Tanks 'bombed up' the AFV and reviewed the information on the cartridge case and projectile itself as loading. They might stow 'fresher' dated ammo deeper inside and get older rounds in the ready racks. They might have a SOP as far as when they could fire Tungsten Carbide ammunition. Anything 'new' would certainly be investigated and brought up with the technically proficient NCO's etc. when your life depends on the details, you can take a deep interest...
 
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NUTTERNAME

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That Rexford data. I'm pretty sure the British didn't post their data in meters. I have a data collection of six 50mm/L60 APC data sets. I added Rexford's data (red line) to the graph and you can see who much out of the norm from the others it is.
http://www.panzer-war.com/Files/50mmdatabase.jpg
Yep, I gotta quote him...
The British data I posted was based on the Critical Velocity for 50% success with German production ammo, where half the hits meet the penetration criteria and half don't.

Plate hardness differences would not amount to much.
 

mOBIUS

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Yeah. That's his old saw about 50% penetration being almost the same as 80% penetration. And hardness doesn't matter much. Some how his numbers don't fit the real data.
The Russian Battlefield had penetration of Russian guns where they give certified penetration (80%) and Initial Penetration (20%). These differ by 13-21% in common guns. So if 80% and 50% are almost the same then 20% and 50% should be as well. How come 13-21% is not?

If you split the difference between 20 and 80 you get 50. So 50% ought to differ from 80% in these guns by 6.5-10.5%.

BTW, that 50mm/L60 Rexford data is close to the US Aberdeen test data for the PaK 38. But that is normalized to 237 BHN. If that is multiplied by a constant 0.9 it falls in line with the other data.
Curious it is called 'British' when it is almost exactly the same as US data. It is curious that the Aberdeen data and British data is the same for this gun. (The 30° Aberdeen data is exactly the same as that of Bovington's data). I wonder who did the testing?
 
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NUTTERNAME

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This just showed up at Archive Awareness.
http://tankarchives.blogspot.com/2016/07/45-mm-apcr.html#more
45mm APCR testing
He doesn't even give a date? I suppose early '42? What German AFV did they fire on? He is a clown.

I saw this interesting drawing for a German sabot round using a Pzgr 39 inside the sabot. It is listed as ammunition for a StuH (105mm) in the April 1944 document. It would be nice to know what sort of velocity and accuracy they could get using supercharge.

View attachment 54192
 

NUTTERNAME

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I hate to get mOBIUS going on about Soviet 12.2 cm, but...I think this graph speaks to my earlier concern regarding the 'dashed-lines' interpolation seen in the US graphs in WWII. Specifically, the larger angles. Note the increasing protection afforded by the ever increasing angle (either from slope or obliquity or a combination of both).

View attachment 54193
 

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That's Lorrin's wheelhouse. I'm not going to take up his mantle. But, try to find the 100mm APBC the AARMC did june 1972.
BTW, they both are not perforation i.e. NBL but Army BL.
 

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That's Lorrin's wheelhouse. I'm not going to take up his mantle. But, try to find the 100mm APBC the AARMC did june 1972.
BTW, they both are not perforation i.e. NBL but Army BL.
He can have it. I am more interested in that test if I can read the full procedure and see photos. I would like to see what a 2.5 inch plate at 70 degrees looks like when holed by that 12.2 cm projectile.

But, to further my point regarding the M62 projectile from the US M1A1 76mm gun at higher slopes, I believe its cap shape is very bad also. Compare to a Pzgr 39 for example.
 
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