# If AP(BC) rounds had correct sloped penetration

First things first… AP rounds shouldn’t have 100% chance of bounce at 63 degrees as it’s currently modelled in WT, not to mention the ridiculous 50% bounce chance at 60 degrees.

Here is AP simulation against armour at 65 degrees

Here is Russian 100mm AP(HEBC) penetration which also includes 70-75 degree penetration, but you know AP rounds totally bounce 100% of the time at 63 degrees (sarcasm)

According to this chart 100mm BR-471B can penetrate 110mm of soft Cast Armour at point blank range (895m/s) at 60 degrees.

2 Pounder AP (40mm, 1.08kg penetrator at 792m/s) penetrates 90mm of armour when it doesn’t deform.

Using 2 pounder as reference in demarre equation for 100mm BR-412 APHE. So the non blunt nose version without aerodynamic cap with 15.78kg penetrator (15.88kg with HE filler) at 895m/s

If 100mm BR-412 APHE didn’t deform against thick flat armour due to lack of piercing cap, it would defeat 273mm of Rolled Homogenous Armour at 0 degrees at point blank range.

AP(BC) slope modifier

100mm BR-412 APHE defeats 101mm at 60 degrees of Rolled Homogenous armour at 60 degrees at point blank range.
101 / 100 = 1.01 T/D Ratio
1.01 T/D at 60 degrees = 2.69 slope modifier
101 x 2.69 = 272mm

AP rounds at 60 degrees don’t deform and if the 100mm AP round didn’t deform at 0 degrees, it would defeat 273mm at 0 degrees.

Conclusion
100mm BR-412 APHE defeats 101mm (60) of RHA

100mm BR-412 APHEBC defeats 110mm (60) of Soft Cast Steel

I think that blunt shells don’t have better sloped penetration or some magical properties against sloped armour. Their flat noses give them utter garbage 0 degree penetration making their 60 degree appear much higher relative to 0 degrees giving us a false illusion of better sloped performance when it’s just the 0 value being atrocious.

As you might have noticed the 60 degree penetration for both the APHE and Russian Blunt Nosed APHEBC is underperforming. All AP rounds in War Thunder are basically missing 25% of their penetration at 60 degrees and they have 50% stupid bounce of chance at 60 degrees on top of that. It essentially artificially and indirectly buffs Russian tanks such as T-34-85 because tanks like Chi-To will have their 60 degree pen underperform by 25% for their AP rounds but they still have enough penetration to defeat them, however there’s 50% chance the round will bounce anyway and if there is additional horizontal angle the chance of bounce increases to 75% and by the time compound angle is 63 defeees for T-34-85 upper plate, you’ll bounce 100% of the time.
Same applies for M103’s M358 AP round vs T-55’s upper plate sloped at 60 degrees.

Note: Russian flat nosed APHEBC uses different slope modifiers which make them UFO at low T/D ratios. At normal high T/D ratios, both the AP and blunt nosed AP rounds are severely underperforming

Sloped Penetration of different rounds after fix

M6 37mm
M74 AP (0.87kg at 884m/s)
36mm @ 0m at 60 degrees

M3 75mm
M72 AP (6.3kg at 619m/s)
45mm @ 0m at 60 degrees

M1 76.2mm
M79 AP (6.8kg at 792m/s)
64mm @ 0m at 60 degrees

M3 90mm
M77 AP (10.61kg at 822m/s)
78mm @ 0m at 60 degrees

M3A1 90mm
T33 / M318 APBC (10.91kg at 853m/s)
81mm @ 0m at 60 degrees

M41 90mm
M318A1 APBC (10.91kg at 914m/s)
88mm @ 0m at 60 degrees

T15E2 90mm
T43 APBC (10.91kg at 975m/s)
96mm @ 0m at 60 degrees

T140E2 105mm
T182E1 APBC (15.9kg at 1067m/s)
120mm @ 0m at 60 degrees

M58 120mm
M358 APBC (23.1kg at 1067m/s)
135mm @ 0m at 60 degrees

On top of such penetration buff, you wouldn’t have 50% chance of bounce at 60 degrees and 100% chance of bounce at 63 degrees

That’s if gaijin had a basic clue about ww2 shell penetration and physics

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We all know things are wrong. Gaijin ground devs don’t want to listen.

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Honestly, it’s wonderful to have guys like you and everyone else trying to make War Thunder as realistic a game as possible, doing an amazing job and reasonable compared to the penetration data out there in the game.
Regarding what you are talking about, that explains to me the reason for the designs of certain postwar ammunition. For example, the fact that the Soviet 122mm and 100mm postwar projectiles were APCBC, and in turn the American ammunition of the M48, M103 and M41 carried AP capless ammunition. The Soviets using those ammunitions so the tips would not break when firing at the M48 and the Americans without capping so that the bullets in inclined armor when breaking would pierce more.

I also think APC(BC) shells should also use AP slope modifier from wwii ballistics.

Report M.7000 A/11 No.1 , Department of tank design armour branch

According to the British, as long as the AP and APC had same penetrator size and the penetrator still had same striking velocity vs high obliquity armour after the piercing cap is out of the way, their penetration should be identical hence why few extra m/s for APC are needed to match AP, just to get the cap out of the way.

20 Pounder APCBC
???mm @ 0 yards (0) - 1020m/s
198mm @ 0 yards (30) - 1020m/s
129mm @ 0 yards (45) - 1020m/s
103mm @ 0 yards (55) - 1020m/s
85mm @ 0 yards (60) - 1020m/s

???mm @ 1000 yards (0) - 930m/s
173mm @ 1000 yards (30) - 930m/s
113mm @ 1000 yards (45) - 930m/s
90mm @ 1000 yards (55) - 930m/s
76mm @ 1000 yards (60) - 930m/s

???mm @ 2000 yards (0) - 840m/s
150mm @ 2000 yards (30) - 840m/s
98mm @ 2000 yards (45) - 840m/s
81mm @ 2000 yards (55) - 840m/s
66mm @ 2000 yards (60) - 840m/s

If we use APC/APCBC slope modifiers in wwii ballistics the 0 degree penetration ends up being unreasonably high

266mm @ 0 yards at 0 degrees with APC(BC) slope modifier

230mm @ 0 yards at 0 degrees with AP(BC) slope modifier

Conclusion
I believe the British conclusion that the AP / APC / APBC / APCBC denormalise just the same way against sloped armour (all should be using AP slope modifier in wwii ballistics book)

20 Pounder APCBC
230mm @ 0 yards (0) - 1020m/s
198mm @ 0 yards (30)
85mm @ 0 yards (60)

202mm @ 1000 yards (0) - 930m/s
173mm @ 1000 yards (30)
76mm @ 1000 yards (60)

174mm @ 2000 yards (0) - 840m/s
150mm @ 2000 yards (30)
66mm @ 2000 yards (60)

20 Pounder APCBC vertical penetration when using AP slope modifier from wwii ballistics, armour and gunnery, calculated from 60 degree value

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