First Round Accuracy of German Guns

[rexford]

FIRST ROUND ACCURACY OF GERMAN GUNS

The following hit percentages are taken from German ballistic tables (capped AP) and refer to the case where the range is known to a stationary 2m high by 2.5m wide target, and the random dispersion is doubled to model battlefield conditions:

RANGE..50L60...75L48...75L70...88L56...88L71

500m........100.....100.....100......100.....100

1000m.... ...95......66......97.......93......85

1500m........68......33......72.......74......61

2000m................16......49.......50......43

2500m.................8......29.......31......34

3000m.................5......18.......19......25

Relative dispersion in the above table follows some unexpected patterns, with 75L70 being less scatter prone than 88L56 out to 1000m, but after that range 88L56 is slightly more accurate in terms of repeatability. With regard to 88L71, the scatter pattern is more diffuse than 75L70 and 88L56 at ranges out to 2000m but then attains a superior performance at 2500m which increases with range.

German data for their use of the captured Russian 76.2mm L51.5 gun showed dispersion patterns similar to the 75L48 when APCBC was fired., with similar hit percentages with a known range.

The 50L60 and 88L71 data applies to both the tank gun and towed weapons, while the 88L56 figures are limited to the tank gun. Review of data for the 88mm L56 Flak suggests that that weapon may have possessed greater dispersion than the tank gun.

The marked inferiority of 75L48 scatter to the other guns is unexpected., since the 75L43 was used to knock-out T34’s at ranges above 1000m. It would be interesting to see if 75mm L46 Pak 40 dispersion had the same general values as the 75L48, which came along at a later date.

It has been written that the introduction of the 50mm Pak in Africa greatly extended the range of direct fire combat for tank and anti-tank gun units, and the relatively close scatter pattern and excellent gun sight quality for that weapon would be superior to the 2 pdr anti-tank gun in both respects.

Using the German figures for doubled random dispersion and assuming an average range estimate error of 25% with a bell shaped error distribution (typical results for average crew, based on British and American firing trials), the following first round hit percentages were computed against a stationary 2m high by 2.5m wide target:

FIRST ROUND HIT %

RANGE...50L60...75L48...75L70...88L56...88L71

500m...........81......75.....88.......79.....94

800m...........36......34.....51.......39.....61

1100m..........17......15.....28.......21.....34

1400m...........9.......7.....16.......12.....19

Muzzle velocities are 835 m/s for 50L60, 750 m/s for 75L48, 935 m/s for 75L70, 780 m/s for 88L56 and 1000 m/s for 88L71. All rounds APCBC except APC for 50L60

A 2m x 2.5m target size was used by the Germans as a reasonable model for the front view of a typical target tank, which simplified the calculations. Those dimensions simplify the complex variations in target width with height (T34 turret front is narrower than hull and has sloping sides, T34 hull width varies with height, etc.), and probably assume that ground rolls and folds blocked out some of the lower tank area.

The above stated estimates for first round hit percentage probably represent the high side of what would be expected from average troops in battle, since “nervous and/or fatigue” origin errors were not considered during the calculations. Under the stress of combat, people can forget intermediate steps and see things on the gun sight that are not there. Discussions on the AFV News forum site have brought out the possibility that unquantifiable human errors may account for a good share of the reported misses at “sure thing” ranges.

Regarding second shot corrections after misses, the Germans advised that bracketing should be used at ranges above 1200m using 200m increments below 2000m and 400m above that distance. At or below 1200m, "fire for effect" corrections to the initial shot would be made using various methods that would result in a more accurate change in shot placement than adding or subtracting 200m.

An American gunnery manual for the Sherman indicates that bracketing is to be used at ranges over 1000 yards due to gun sight limitations which restrict the crew ability to make fine adjustments to the gun setting.

[ August 14, 2004, 07:45 AM: Message edited by: rexford ]

[Mr. Tittles]

The German 75mmkwk37 (stump L24) had better numbers than the L48? I really doubt that.

http://gva.freeweb.hu/weapons/german_accuracy5.html

75mmL24 __500__1000__1500

Dispersion __100__98___74

Firing (DD)__100__73___38

[ August 15, 2004, 09:30 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

If I understand this correctly, the guns are put in a test fixture and fired so as to get the dispersion spread against a 2 x2.5 m target? Then this dispersion is doubled (in both height/width)? And this is your double dispersion? I would expect width to be easier to hit than height. Simply because of the larger dimension. So if a single dispersion can get 10 rounds within a 1 meter height difference, centered about the middle of the vehicle, then a double dispersion might also achieve 100%?

Its actually a huge error margin considering it does not account for THE biggest problem in gunnery; range estimation. I take it you fold that into double dispersion to crank out these low first shot hit probabilitys?

[ August 15, 2004, 10:19 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

You are saying that 50mmL60 is twice as accurate as a 75mmL48 at 1500m (single dispersion)? Could that 75mm data possibly be for HEAT or HE?

You are then saying that after DD and range fudge, both 50mmL60 and 75mmL48 go down to 9% and 7% respective?

German HEAT projectiles had muzzle velocities of less than 600m/s, and usually less than 450m/s. Although Hogg quotes various effective ranges in German Artillery of World War Two of 1,000m and more, these must be viewed with some suspicion. A report from the Infanterie-Division “Grossdeutschland” on 3 April 1943 as quoted in Jentz’ Panzer Truppen Vol 2 gives an indication of the true effective range:

“Our own Panzerkopfgranate (i.e. APCBC or APCR) are exceptionally effective and amazingly accurate. However, to the contrary, due to its large dispersion the HL/B-Granaten (shaped charge shells - i.e. HEAT) is usable at a maximum range of 500 metres. If a hit is obtained at long range by expenditure of a high number of rounds, the effect of the HL/B Granate is good. However the troops have no faith in the HL/B-Granate. It is desired that the supply of Panzer-Kopfgranaten be increased.”

At the time the division had 10 Pz.Kpfw.IV with 7,5cm Kw.K.37 L/24 and 75 Pz.Kpfw.IV with the longer barrelled 7,5cm Kw.K.40 L/43, as well as various other vehicles. The report quoted above indicates that the maximum effective range of Gr.38 Hl/B is 500m for these vehicles. Hits could be achieved at greater ranges but only by firing many rounds.

[ August 15, 2004, 10:13 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

It has been written that the introduction of the 50mm Pak in Africa greatly extended the range of direct fire combat for tank and anti-tank gun units, and the relatively close scatter pattern and excellent gun sight quality for that weapon would be superior to the 2 pdr anti-tank gun in both respects.

http://gva.freeweb.hu/weapons/german_accuracy3.html

The reason might be better penetration but according to data, the L60 and L42 were about the same accuracy.

[rexford]

Dispersion figures taken from official German ballistic tables for the listed guns, and the 75L48 data applies to APCBC fired at 750 m/s.

[rexford]

Originally posted by Mr. Tittles:

If I understand this correctly, the guns are put in a test fixture and fired so as to get the dispersion spread against a 2 x2.5 m target? Then this dispersion is doubled (in both height/width)?

No. The guns are aimed at a given range and the vertical and lateral dispersion patterns are measured and analyzed using statistics.

The German ballistic tables present the 50% zone for single dispersion, the vertical and lateral distances that capture 50% of the shots.

I converted the 50% zones into 68% zones, and then calculated the hit % against a 2m high by 2.5m wide target using the twice the test results for lateral and vertical scatter pattern statistics. Vertical dispersion is usually greater than lateral dispersion.

[Mr. Tittles]

So a 75mmL48 is less accurate than a 75mmL24 and also a 88mmL56 firing HEAT? The most numerous German KWK was that innaccurate?

88mmL56 HEAT Tiger I

____________500__1000__1500__2000

Dispersion ___100 __94__ 72__ 52

Firing ________98__ 62__ 34__ 20

Gun Accuracy Data

The Gun Accuracy tables show the results of two types of tests: dispersion and firing.

Dispersion tests show the percentage of projectiles that will hit a 2.5m × 2m target during controlled test firing. The pattern of dispersion is assumed to be centred exactly on the target. These results give a good theoretical comparison of guns and ammunition types, without considering the complicating effects of human error.

Firing tests show the expected percentage of projectiles that will hit a 2.5m × 2m target by a gunner during practice firing on a gun range. It is obtained by doubling the dispersion pattern obtained from the dispersion test data. The British, Germans and Italians all considered this to be a close approximation of the accuracy obtained by troops in practice firings and, if they remained calm, in combat when the range to the target is known. Due to errors in estimating the range and many other factors, the probability of a first round hit was much lower than shown in these tables. However, the average, calm gunner, after watching tracer from the first round, could achieve the accuracy shown on subsequent shots.

http://gva.freeweb.hu/weapons/introduction.html#Gun_Accuracy_Data

[ August 16, 2004, 02:14 PM: Message edited by: Mr. Tittles ]

[arax3]

Nazi troops in Italy used 88s like a sniper uses a rifle. How accurate do you need to be? A3

[Mr. Tittles]

FIRST ROUND HIT %

RANGE...50L60...75L48...75L70...88L56...88L71

500m...........81......75.....88.......79.....94

800m...........36......34.....51.......39.....61

1100m..........17......15.....28.......21.....34

1400m...........9.......7.....16.......12.....19

Why are the ranges 500, 800, 1100 and 1400? The first data was 500, 1000, 1500...etc?

[Mr. Tittles]

No. The guns are aimed at a given range and the vertical and lateral dispersion patterns are measured and analyzed using statistics.

The German ballistic tables present the 50% zone for single dispersion, the vertical and lateral distances that capture 50% of the shots.

This differs from what the website says of course (Gus and Armor). I really doubt what rexfolk says.

[rexford]

Originally posted by Mr. Tittles:

No. The guns are aimed at a given range and the vertical and lateral dispersion patterns are measured and analyzed using statistics.

The German ballistic tables present the 50% zone for single dispersion, the vertical and lateral distances that capture 50% of the shots.

This differs from what the website says of course (Gus and Armor). I really doubt what rexfolk says.

I guess you didn't read my earlier posts close enough. Suggest you go back to them and get up to speed on what I said.

I have the original German documents where the hit percentages against a 2m high x 2.5m wide target were estimated. The base data for the calculations is the 50% zone for vertical and lateral dispersion as measured on a firing range.

The firing range did not use a 2m x 2.5m target, so the estimated hit %'s against that target size are estimated. I have a British BIOS on the methods used to determine weapon and ammo dispersion zones, and they did not use a 2m x 2.5m target.

[rexford]

"Firing tests show the expected percentage of projectiles that will hit a 2.5m × 2m target by a gunner during practice firing on a gun range. It is obtained by doubling the dispersion pattern obtained from the dispersion test data."

As noted in my previous post, the Germans first fired their guns and ammo against targets, then they analyzed the data statistically to determine the 50% zones.

Then they applied the 50% zone data to compute the hit % against a 2m x 2.5m target using single and doubled dispersion. That is the correct explanation of what the data means.

We have had the German ballistic tables with dispersion 50% zones and computed hit %'s against a 2m x 2.5m target for over twenty years, and have studied the heck out of the info.

[Mr. Tittles]

You never said they were estimated in the first post of this thread. Suggest you go back and edit.

FIRST ROUND ACCURACY OF GERMAN GUNS

The following hit percentages are taken from German ballistic tables (capped AP) and refer to the case where the range is known to a stationary 2m high by 2.5m wide target, and the random dispersion is doubled to model battlefield conditions:

Later on in the thread you explain something about converting 50% to 68% or something.

And my orig claim stands then. I suggest you go back and read it.

[ August 17, 2004, 08:23 PM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Quite frankly, I would prefer to see the raw data. Germans are wierd when it comes to kanoodling data.

[Mr. Tittles]

75mmL24 __500__1000__1500

Dispersion __100__98___74

Firing (DD)__100__73___38

I think the casual reader should consider that these weapons WERE accurate.

Think of Firing (DD or double Dispersion) as a good approximation of a second shot chance (gunner with training not stressed)... Especially at shorter ranges (not less than 500m where human factors can get excessive).

Dispersion might be understood as a 3rd shot chance for competant gunners that are in control.

Even a 75mmL24 could repeatbly hit a tank sized target after the third round at 1000m typically (and many tanks were larger than 2mx2.5m). After a BOT (burst on target), it could hit it almost continually! It is firing a spin stabilized massive hunk of metal. It isn't shooting spitballs with both eyes closed.

I understand that rexword is trying to get to some kind of first round fudge-about. But I think that unless similar data can be found for allied guns and the odd 75mmL48 data challenged, he may have some say in future patches/games from BTS.

PS I will reiterate my point made earlier. If you look at the 500m data, both are 100%. To me that means that Dispersion rounds are falling within 1 meter height delta. If we double that dispersion, then a 2m height delta still captures them. First round shots at 500m may certainly be influenced by many factors. It would not be a sure kill in any case.

[ August 17, 2004, 08:55 PM: Message edited by: Mr. Tittles ]

[rexford]

Originally posted by Mr. Tittles:

Think of Firing (DD or double Dispersion) as a good approximation of a second shot chance (gunner with training not stressed)... Especially at shorter ranges (not less than 500m where human factors can get excessive).

Dispersion might be understood as a 3rd shot chance for competant gunners that are in control.

Even a 75mmL24 could repeatbly hit a tank sized target after the third round at 1000m typically (and many tanks were larger than 2mx2.5m). After a BOT (burst on target), it could hit it almost continually! It is firing a spin stabilized massive hunk of metal. It isn't shooting spitballs with both eyes closed.

I understand that rexword is trying to get to some kind of first round fudge-about. But I think that unless similar data can be found for allied guns and the odd 75mmL48 data challenged, he may have some say in future patches/games from BTS.

PS I will reiterate my point made earlier. If you look at the 500m data, both are 100%. To me that means that Dispersion rounds are falling within 1 meter height delta. If we double that dispersion, then a 2m height delta still captures them. First round shots at 500m may certainly be influenced by many factors. It would not be a sure kill in any case.

At 1000m range the 75L48 APCBC single dispersion for 50% of shots is 0.6m vertical and 0.5m lateral. The distances to capture 68.3% of the shots is about 0.9m vert and 0.75m lat.

The Germans assumed that on a battlefield the dispersion would be doubled due to out of perfect alignment guns, less than perfect gunners, etc.

So the 68.3% doubled dispersion distances would be 1.8m vertical and 1.5m lateral, and half of that is 0.9m vertical and 0.75m.

If 68.3% of the 75L48 APCBC shots at 1000m are up to 0.9m above or below the center of target aim point, and are up to 0.75m left or right of the center aim point, it is obvious that less than 100% will hit a 2m high by 2.5m wide target when the gun is aimed at 1000m range.

If one looks at the single dispersion situation, a first round hit might be due to a combination of an incorrect initial range estimate and random scatter that brings the round back onto the target. The second round could then miss, or the second round could hit and the third round might miss.

Nothing is 100% sure even if everything seems to have been done correctly, and random dispersion could mislead the gunner and commander into believing they had the correct range (when they didn't) or had a wrong range setting (when they were pretty good).

We created a computer program using random dispersion data and range setting inputs to see what a gunner would typically experience in terms of fall of shot on a series of shots, and ran the program over and over with different initial range estimates. Random dispersion messes things up, you think you're aiming high but the aim is near or on center, you hit the target but the aim is actually off the target.

Burst on Target is great in theory, but what if one cannot see where the round hits the ground in front of the target? How does one figure out which trajectory point to use on a high shot?

It is very difficult to tell what the trajectory height is at the point where the round just passes over the target tank. If one uses the maximum trajectory height that may be way off the mark. Remember, we're talking about rounds fired at targets 1000m away and the total flight time for 75L48 APCBC is less than 2 seconds.

If there are trees in back of the target and the tracer isn't observed too well for any number of reasons, burst on target goes out the window on high misses.

On low misses that bounce in the dirt or on the grass, the estimated height of the trajectory may be much lower at the target than where the round hit the ground, so one can be off on low misses too.

Burst on target is not a 100% surefire follow-up shot technique.

[ August 21, 2004, 09:40 AM: Message edited by: rexford ]

[Mr. Tittles]

http://www.battlefront.com/cgi-bin/bbs/ultimatebb.cgi?ubb=get_topic&f=23&t=010029#000006

I think you should reply to questions regarding your methodology that have been brought up in this thread.

My main concern is that you are applying statistics incorrectly to the data.

I also think the Double Dispersion 'factor' is way too fudgey and is at best a worst case scenario (if applicable under most conditions).