Accuracy values for the main guns - MBT's.

[Fabfire]

This one being my first post here, I would like to thank Andy, Don, & The Camo Workshop for what is, IMHO, the best version of SP ever - God, after 10 years - SP, SP2, SP3, SPWAW - I can reverse a tank!!

However, perhaps the accuracy (for the tank's main guns) values should be reviewed, since my impression is that they do not represent the tank gun's actual accuracy. The rule of thumb in WinSPMBT is "the length in calibers divided by 4" (this is from the manual, under the item "Accuracy"). So, a German 120mm L/55, will have an accuracy value of 14, and the German 120mm L/44 will have an accuracy value of only 11... The same with the American M256 of the all versions of the M1A1/A2. And the Israeli 120mm of the Merkava and each and every tank that uses some 120mm L/44, too. And then we have the British Challenger's guns, with an accuracy value going up to 16 (I am not bashing the British rifled 120mm guns - they are deadly accurate, but perhaps not so much more than the German 120mm L/44, which has a value of only 11), and the Soviet/Russian 125mm guns a value of 13.

Would Rheinmetall design a gun less accurate than the Soviet 125mm guns? I don't believe so. That's against the company's tradition and reputation. And no, I don't work for Rheinmetall...

I just want to point out that maybe gun length is not the best factor in determining tank gun accuracy, there are many other factors involved such as the quality of the materials used in the gun itself and how it behaves with the propellant used, the chamber pressure, etc. All these factors are exclusive of the tank gun itself, not the FCS. And they are relevant where accuracy is concerned.

I am really not convinced of the "longest gun is the most accurate one" accuracy principle, specially when the latest tank guns are compared to the old Soviet guns. I mean, by the time of their respective development and posterior deployment, why the Hell would Germany and the US implement a gun on the Leopard 2 and M1A1 Abrams that were less accurate than the guns used in the same Soviet tanks they were supposed to defeat? Again, I am not speaking of the effects of the different FCS systems used, I am referring to raw gun accuracy.

Most respectfully, I would like to hear Andy and Don's comments on this issue.

[Listy]

Hullo kevineduguay1... **Waves**

If you're not, then appolgies. There's been this disscussion over at the DosMBT group, the following reply was given (Edward is talking about the formula used for working out the ACC):

Edward R. Mortimer said:
Y'see, what we have works very well through WWII and even into the
1970's . . . and then breaks down because of the advances in
munitions. The problem is . . . most of that data on munitions in the
last 30 years are classified. Getting a coherent grip on the situation
is not easy. Yes, everyone knows the current formula is not perfect.
But it works well enough when ALL the other variables are used in the
formula (not just ACC, FC & RF, but ALL the variables). ACC is only
representative of firing a generic munition over iron sights, something
which none of these modern tank guns will do intentionally.

Remember, the game has to deal with HE, AP, HEAT, HESH, and all the
varieties of so-called SABOT munitions. Each of which has its own
characteristics (i.e. velocity, drag, etc) . . . but the game demands
that all of them be merged into one identity for the purpose of
accuracy.

So you see it is not that we haven't thought about it, but that we
haven't come up with a better universal formula yet. But to say the
in-game Soviet tanks are better than the in-game Abrams because of a
minor 2 points in ACC rating, yet ignore massive differences in other
ratings that are part of the formula, is ridiculous.

[JaM]

In fact, US Army had accuracy problems during testing german 120mm L55 Gun firing new US APFSDS rounds (M829A2,M829A3)Its accuracy with this rounds was much worse than with M256 gun (L44)

[JaM]

Discusion on Yahoo board is quite big. Accuracy system works great until 1970, after this date new ammunitions are avaiable and this should be taken into account. I know that most of datas are classified, so you need a formula that will work for all tanks with data avaiable. My sugesstion is use L/D ratio of APFSDS projectiles as measurment for accuracy and degree of technology of tank gun. Soviet tank guns were quite unaccurate at ranges over 1600m,they used APFSDS rounds with L/D ratio 10:1 - 13:1,newest projectiles has better accuracy (BM-42,BM-42M etc...)guns that fires them are upgraded so they can fire longer rounds with better L/D (20:1, autoloader prevents to use longer rounds such as US M829A2 or A3 with L/D 30:1 - 37:1).Western tanks started with L/D 10:1 (M735) but they develop better ammo quite soon as M774(not so sure but it is in L/D 15:1 - 20:1 region) M833 (L/D around 20:1) or M900 (L/D 30:1).
Im not suggesting use L/D value as a acc value, but just better variable than lenght of gun.Soviet HEAT ammo for example are stated as more accurate as APFSDS rounds (0,2mil dispersion for HEAT-FS and 0,25-0,3mil for APFSDS)

[Fabfire]

Listy said:


Hullo kevineduguay1... **Waves**

If you're not, then appolgies. There's been this disscussion over at the DosMBT group, the following reply was given (Edward is talking about the formula used for working out the ACC):

Appologies accepted. I am not kevineduguay1...

I don't think that a 2 points difference is ridiculous, because it affects not only the Abrams, but also the Leo 2 (up to the A4), Merkava...etc. What seems ridiculous is Western 120mm L/44 being rated as inferior to old Soviet 125mm guns. I am not ignoring other problems with the accuracy formula, it's just that as I have a little more knowledge on tank guns performance, it came to my attention first.

By this formula, who can garantee that even the Leo 2A6 120mm L/55 accuracy of 14 is right? Or even the Challenger's rilfed guns? What we need is a better general formula.

Finally, I still remain with the same doubts I posted.
But thanks for the answer, anyway.

[Fabfire]

JaM said:
In fact, US Army had accuracy problems during testing german 120mm L55 Gun firing new US APFSDS rounds (M829A2,M829A3)Its accuracy with this rounds was much worse than with M256 gun (L44)

Yep. I know that. But this was due to the incompatibilities of the new German gun with the US DU APFSDS rounds, that were developed to maximize the potential of the 120mm M256 gun. This does not implies, in any way, that the Rheinmetall 120mm L/55 would be less accurate than the 120mm M256 (a modified Rh 120mm L/44 gun), once the DU ammunition is optimized for this gun.

[Fabfire]

JaM said:
Discusion on Yahoo board is quite big. Accuracy system works great until 1970, after this date new ammunitions are avaiable and this should be taken into account. I know that most of datas are classified, so you need a formula that will work for all tanks with data avaiable. My sugesstion is use L/D ratio of APFSDS projectiles as measurment for accuracy and degree of technology of tank gun. Soviet tank guns were quite unaccurate at ranges over 1600m,they used APFSDS rounds with L/D ratio 10:1 - 13:1,newest projectiles has better accuracy (BM-42,BM-42M etc...)guns that fires them are upgraded so they can fire longer rounds with better L/D (20:1, autoloader prevents to use longer rounds such as US M829A2 or A3 with L/D 30:1 - 37:1).Western tanks started with L/D 10:1 (M735) but they develop better ammo quite soon as M774(not so sure but it is in L/D 15:1 - 20:1 region) M833 (L/D around 20:1) or M900 (L/D 30:1).
Im not suggesting use L/D value as a acc value, but just better variable than lenght of gun.Soviet HEAT ammo for example are stated as more accurate as APFSDS rounds (0,2mil dispersion for HEAT-FS and 0,25-0,3mil for APFSDS)

That's interesting. Thank you. However, I still would like so much to hear from Andy and Don on this subject...

[JaM]

M256 said:

That's interesting. Thank you. However, I still would like so much to hear from Andy and Don on this subject...

Me too..

By the way, i have some numbers about our Slovak modernisation of 2A46 gun (2A46MS) from Slovak military bulletin, gun during tests was 30% more accurate than original gun

[Fabfire]

JaM said:

Me too..

By the way, i have some numbers about our Slovak modernisation of 2A46 gun (2A46MS) from Slovak military bulletin, gun during tests was 30% more accurate than original gun

I am interested in those tests data. Can you post it on this Forum?

[JaM]

yes,i will post them, yust need to translate them to english,tomorow