WWII Tank Gun Specifications

[Soren]

Stop saying you and others have pointed something out when you're the only one making the claims Dunmunro.

An no APDS rounds were not as good against sloped armour as any other round, APDS APCR rounds suffered a greater loss in penetration performance with increases in armour slope than APCBC rounds did. Sorry but that's how it is. And when the APDS round did penetrate it didn't do as much damage as APCBC rounds, esp. not those equipped with an internal explosive charge. And again, APDS was in short supply.

 

[Soren]

Hello Soren
and the explanation why 17pdr Sabot didn't work well at U.S. Army Firing Tests conducted August 1944 by 12th U.S. Army Group at Isigny, France, from the same paper, straight after my earlier quote.

"The conflict between these results and those obtained by the board is explained by Col. A. G. Cole, Deputy Director of Artillery, Ministry of Supply. Col. Cole witnessed part of the test and states that the ammunition lot furnished the board had not been proof fired. He further states that, in his opinion, the lot is of sub-standard manufacture and if proof fired would not have been accepted."

So 17pdr Sabot used in Isigny was most probably sub-standard, so it's rather useless to draw too much from it on the behaviour of 17pdr Sabot.

Juha

Juha,

In terms of its behavior in regards to accuracy it can definitely be relied upon, esp. since the inaccuracy is confirmed by other sources and explained in detail by others. I would however not rely on the armour penetration performance of the APDS rounds in those tests, as this was going to be affected if Col. Cole was right.

 

[Juha]

Yes, I meant the ability to penetrate.
accuracy of 17pdr Sabot wasn't very good, all 5 shots hits the Panther from 700y but only 2 the aiming point, the glacis. But 3 penetrated, so 60% chance to disable a Panther from 700y head on, not bad but definitely worse than Panther's chances to disable Firefly from 700y, IMHO Panther chances in similar conditions would have been near 100%.

Juha

 

[dunmunro1]

Stop saying you and others have pointed something out when you're the only one making the claims Dunmunro.

Did you not read this post?
http://www.ww2aircraft.net/forum/ww2-general/best-tank-ww2-20189-9.html#post615840

 

[Soren]

Yes, I meant the ability to penetrate.
accuracy of 17pdr Sabot wasn't very good, all 5 shots hits the Panther from 700y but only 2 the aiming point, the glacis. But 3 penetrated, so 60% chance to disable a Panther from 700y head on, not bad but definitely worse than Panther's chances to disable Firefly from 700y, IMHO Panther chances in similar conditions would have been near 100%.

Juha

True. The Panther's gun would've had no problems penetrating the Sherman's armour that's for sure, the rest depends upon what damage the projectile does once it enters the inside of the tank. But I'd like to point out that ude to the fact that the APCBC round was better against sloped armour it therefore likely be able to penetrate the Panther's glacis from a longer range with greater success than the APDS round, probably out to 850 to 900 yards.

 

[dunmunro1]

I found some accuracy test data for the 6 pdr:

This test also featured 17 pdr shots but these are complicated because the 17 pdr gun crew was not very experienced.

To summarize the results:

Tiger and Panther targets
at 1000 yds for 17 pdr
at 600 yds for 6 pdr.

17 pdr APDS lot 1 = 5 fired = 1 hit which holed the glacis plate after passing through track guard.
17 pdr APDS lot 2 (mackie) = 6 fired = 6 hits but only 1 fatal hit
17 pdr APCBC = 14 fired = 7 misses

6 pdr APDS = 24 fired = 1 miss
6 pdr APCBC = 31 = 4 misses

 

[Soren]

I don't think that report should be used as a benchmark for the accurracy with different ammunition types as it wasn't a test meant to test accuracy and because of the clear misjudging of range on a magnitude as great as 300 yards short. Misjudging range with higher MV rounds is also harder as they simply don't plummit as fast with range.

 

[dunmunro1]

I don't think that report should be used as a benchmark for the accurracy with different ammunition types as it wasn't a test meant to test accuracy and because of the clear misjudging of range on a magnitude as great as 300 yards short. Misjudging range with higher MV rounds is also harder as they simply don't plummit as fast with range.

The 6 pdr results were not effected by ranging errors. The accuracy of the 6 pdr APDS is noted, in fact, and match the expected results for the two ammo types.

 

[Soren]

I don't like it that any rounds missed at all at that range (600y) Dunmunro. The 6 pdr should be able to hit with every single round using APCBC at 600 yards, esp. on a target as big as the Tiger Panther. And if the APDS rounds were as accurate as the APCBC rounds I'd expect no misses with that either. Something wasn't done right, the gun was more accurate than that, and the simple fact that it wasn't a test specifically tasked to determine accuracy also has me lean more in this direction.

 

[dunmunro1]

True. The Panther's gun would've had no problems penetrating the Sherman's armour that's for sure, the rest depends upon what damage the projectile does once it enters the inside of the tank. But I'd like to point out that ude to the fact that the APCBC round was better against sloped armour it therefore likely be able to penetrate the Panther's glacis from a longer range with greater success than the APDS round, probably out to 850 to 900 yards.

Please provide some data showing that the APCBC round is better against sloped armour. This statement runs completely contrary to all the penetration data that I've seen. Even if the APDS performance falls off to a relatively greater degree with increasing target angle it still has such a lead that the APCBC will never catch up.

 

[dunmunro1]

I don't like it that any rounds missed at all at that range (600y) Dunmunro. The 6 pdr should be able to hit with every single round using APCBC at 600 yards, esp. on a target as big as the Tiger Panther. And if the APDS rounds were as accurate as the APCBC rounds I'd expect no misses with that either. Something wasn't done right, the gun was more accurate than that, and the simple fact that it wasn't a test specifically tasked to determine accuracy also has me lean more in this direction.

The chart I provided here:
http://www.sfu.ca/~dmunro/images/accuracy.jpg
shows a 50% hit probability at 1000 yds for the APCBC and 1100 yds for the APDS. The 100 percent probability range for APCBC is most likely to be ~500 yds, so at 600 yds we can expect ~90%, which is what the results showed - 87% for the APCBC and 97% for APDS. In any event if 6 pdr APDS had a tendency to be inaccurate it certainly didn't show up.

 

[Soren]

Please provide some data showing that the APCBC round is better against sloped armour. This statement runs completely contrary to all the penetration data that I've seen. Even if the APDS performance falls off to a relatively greater degree with increasing target angle it still has such a lead that the APCBC will never catch up.

Data ? I have provided plenty of data to prove that fact already. Also if you don't understand why APCBC rounds are more effective against sloped armour than solid shot AP then I suggest you read up on it. I can tell you that it was simply the addition of a soft metal cap which improved the penetration performance against sloped armour as compared to uncapped projectiles. The APDS round, being a solid shot itself once the shoe had seperated, behaved just the same as a normal solid shot AP round.

 

[Juha]

Hello Soren
Quote:" the APCBC round was better against sloped armour it therefore likely be able to penetrate the Panther's glacis from a longer range with greater success than the APDS round, probably out to 850 to 900 yards."

Now that was not the finding of the Isigny test, their report stated: " The 17pdr APCBC is somewhat superior to the 76mm HVAP, T4, against the Panther Tank. Neither one can be be depended upon to penetrate the glacis plate of the Panther in one fair hit on average quality plate."
Of course with 17pdr APCBC the gunner could aim the middle horizontal band of the mantlet or those parts of turret front visible, both of which were penetrable to APCBC from fairly long distances but they were clearly smaller targets than the glacis. The sideprotection of Panther wasn't never a problem, even 2pdr without littlejohn could penetrate Panther's turret side from appr. 400y.
at Balleroy both fair APDS hits from 700y on glacis penetrated as did the hit at the junction of the nose and glacis. Only a very small sample but indication is that good quality 17pdr sabot penetrates from that distance the glacis if it hits.

Juha

 

[Juha]

Hello dunmunro
thanks again for the info!

Juha

 

[dunmunro1]

No problem. I just want to put this image:

here, for the sake of continuity.

 

[Soren]

Tank nose down by 6 degree's, that means the effective slope of the Panther's glacis was reduced to 49 degrees from an original 55 degrees. That will make a noticable difference, and clearly did compared to the Insigny tests.

 

[dunmunro1]

it does aid penetration of the glacis plate, but then it also adds 6 degs to the nose plate, putting it at 61deg and, of course, there is also a 10deg target angle.

 

[Soren]

Hello
from "Fire and Movement", RAC Tank Museum, Bovington, 1975, pages 22–25. "Penetration v. homogenous armour at 30º, at ranges in yards". The armour is machineable quality.

6pdr Mk 5
500____1000_____1500____2000y
87_______80_______73______67mm

Ammo must have been Mk X T APCBC 7.13lb (appr.3,23kg) 2780fps (appr. 847m/s). One explanation is the differences between US and GB ammo. In US test the shot loss its penetration power faster than in GB test. When we use simple LOS principle the first two figures are appr. equal but then the US test gives weaker performance than the GB test.

Seems more likely that these results were achieved at a 90 degree angle (If it was the Mk.5T atleast), then they also fit well with the US test results. A penetration performance of 67mm of RHA armour angled at 30 degree at 2,000 yards seems way above what any APCBC projectile of that weight and velocity is capable of.

 

[Juha]

Hello
re scan in dunmunro's message #55, now IMHO that's clearly a Tiger.

Soren
I cannot help, usually RAC Tank Museum info is good. As I wrote earlier US tests might well be made using US made ammo. They produced both 57mm A/T gun and ammo for it, so it would have been natural to use them and not transport a British gun and British ammo to the States.

Juha

 

[dunmunro1]

I found the data for the Panther in message 55, and it states that it was nose down by 4.5 to 5 degrees.