Big Guns vs. Armor

[JoMac]

I have played CMx1 for many years, and some things regarding large Guns vs Armor that bothers me.

I have read reports some years ago that anytime a JS2 with its 122 high-velocity gun hits a Tiger or Panther it would simple just explode ( turret comes flying off, hull cracked, suspension blown apart, crew casualites, etc ). However, in CM it seems that these large bore high-velocity guns have little affect if the shell itself doesn't penetrate.

I also wonder the same thing with Large bore small caliber guns like the SU122, M4-105, StuH-105, etc, vs Armor. What effect would these have on Armor if no penetration occurs.

While on the subject, I also play Red Orchestra ( WWII 1st person shooter ), and in the process of helping out with some Armor & Gun modeling. I want to try and model the KO accuracy of these larger bore guns.

A JS2 for example would not KO a Tiger or Panther in one hit ( like I think it should regardless of penetration or angle ), but can take several to the hull ( especially if at an angle ) where rounds harmlessy bounce.

Actually, RO has its own ways of handling armor.

It usually takes a couple penetration hits to get a KO, and sometimes more.

Any info would be appreciated.

Thanx, Joe

[Joachim]

I have played CMx1 for many years, and some things regarding large Guns vs Armor that bothers me.

I have read reports some years ago that anytime a JS2 with its 122 high-velocity gun hits a Tiger or Panther it would simple just explode ( turret comes flying off, hull cracked, suspension blown apart, crew casualites, etc ). However, in CM it seems that these large bore high-velocity guns have little affect if the shell itself doesn't penetrate.

Well... the most recent hit I saw was a partial pen that caused some crew kills and thus led to an abandoned Tiger (might have been HE).

I remember a long range 122L48 partial pen on the front upper hull of a JPzIV/70(V) at well above 1km. Abandoned. Its 75mm round penetrated the front of the ISU122 a split second earlier. No effect.

In my expereince larger rounds tend to have a bigger behind armor effect and thus kill or brew more often in CMx1. While 75mm rounds tend to penetrate 45@20° but then fail to do damage.

[rune]

You are over-simplfying the gun effects. From a Russian web site:

The first example of the A-19 tank gun was ready on November 12, 1943 — the barrel of the D-2 gun was removed from the M-30 gun carriage and installed in the D-5T base after after reducing its diameter. The T-shaped muzzle brake design was borrowed from the D-2 gun. The unusual muzzle brake was intended to reduce the main disadvantage of any muzzle brake: when a shot is fired, a large cloud of dust is kicked up from the ground, revealing the position of the tank. The T-shaped muzzle brake was intended to minimise any dust plumes due to firing.

The JS-122 (Object No.240) passed the Government tests quickly and successfully. Thereafter, the tank was moved to one of the Moscow military testing grounds where it was demonstrated to K. E. Voroshilov. The tank's 122 mm gun was fired from 1500 metres at a captured German Panther tank.

The round hit the side of the Panther's turret, penetrating it cleanly and tearing the opposite side out at the welded seams, throwing it back a few metres. During these tests the muzzle brake of the A-19 blew up almost killing Voroshilov. After this accident it was decided to change the muzzle brake to a 2-chamber design similar to that used by the Germans.

The first part of production JS-1 tanks was delivered in October of 1943, and the JS-2 — in December. At the same time ChKZ continued to manufacture KV-85 tanks until the end of 1943.

In January of 1944 the last 40 JS-85s were manufactured at the ChKZ. After this, it produced only the JS-122. These mounted the new 122 mm Tank Cannon D-25T with a wedge-shaped semi-automatic breech, which allowed an increased rate of fire from 1–1.5 shots per minute to 1.5–2 shots per minute. In March 1944, the «German-type» muzzle brake was replaced with a better design from the TsAKB. At the same time, the JS-85 was renamed JS-1, and the JS-122 was renamed JS-2.

At this stage, the issue of the JS-2's armament was not completely resolved. The military was not satisfied with its low rate of fire and limited ammunition stowage — only 28 two-piece rounds (compared to the 59 one-piece rounds for the JS-1 and 114 one-piece rounds for the KV-1S).

Further, after the first encounters between the JS-2 and German heavy tanks, it turned out that the sharp-nosed 122 mm APHE round — BR-471 — could only penetrate the frontal armour of a Panther up to 600–700 metres. The less powerful frontal armour of a Tiger could be penetrated at distances up to 1200 metres. However, at such distances only very well trained and experienced gunners could score a hit. The vertical armour of a Tiger I, although thicker than that of a Panther, was more easily defeated by the sharp-nosed projectile of the JS-2 Main Gun, whilst it often ricocheted off the sloped armour of a Panther. Later, Soviet designers noticed the blunt-nosed projectiles worked fine against sloped armour. After several tests, designers revealed the effect of «normalisation». The powerful HE round, OF-471, when fired at German tanks, caused cracking and could even completely tear off the front armour plate at the seam weld. The first results of the IS-2 in combat (backed by the results of its tests at the Kubinka testing grounds in January of 1944) forced designers to look for new solutions to its problems.

However, in the summer of 1944, the problem of the poor AP performance disappeared. The performance of the D-25T gun of the JS-2 against the German tanks improved dramatically. The reports from the front described cases where the BR-471 APHE round 122 mm projectile fired from 2500 metres ricocheted off the front armour of a Panther leaving huge holes and cracks in it.

This was explained by an interesting change of circumstances in the Summer of 1944. The Germans experienced a shortage of manganese and had to switch to using high-carbon steel alloyed with nickel, which made armour very brittle, especially at the seam welds. The first encounters of JS-2 tanks with the Germans also showed that the front protection of its hull was not impenetrable.

In the beginning of 1944, an attempt was made to improve the protection of the JS-2 by tempering the front armour to very high hardness. In practice, it led to a drastic increase in the number of components needed for the hull and significantly increased the cost of the tank's production.

So it comes down to the year, the armour material, the type of ammo, etc. etc.

Rune

[JoMac]

Rune,

Thanks for the great info, and its definately helpful for sure.

[ArgusEye]

My impression is that the large rounds have a better chance to kill crew when they land close to the tank, but if they hit the tank itself, they are almost useless. Target the ground next to the tank, and you'll have the best chance of killing it with HE.

[Kineas]

My impression is that the large rounds have a better chance to kill crew when they land close to the tank, but if they hit the tank itself, they are almost useless. Target the ground next to the tank, and you'll have the best chance of killing it with HE.

AFAIK this is a limitation in CM. A HE round only functions as HE when you hit the ground next to the tank. If you hit the tank itself, the round is treated as a weak AP round.