1) Please post in a new thread when you have a question as it makes keeping track of subjects that much easier.
2) HESH, like HEAT can over-penetrate above the nominal pen + warhead size. (It can also have fuse failure like HEAT and woefully underperform). It can also have critical hits like other AP ammo of course!.
3) HESH causes spalling on plain steel armour - effectively it does
not have to penetrate the armour. It uses the Newton's Cradle effect to push a slug of armour off the back end of the hit plate exactly the same as the executive toy with 5 slung steel balls. If you ping one ball on that toy, the corresponding one on the far side of the stack pops off, ping 3 and 3 pop off the other end - and that's the spalling flying round the inside of the target tank at high velocity.
http://en.wikipedia.org/wiki/Newton%27s_cradle
So like flame weapons, HESH has a chance to go right through the armour, more so if its a larger warhead size.
3a) Conversely, HESH
hates spaced or laminated armour, so if the HEAT armour exceeds steel on a face, the difference is multiplied
several times and then deducted from the HESH penetration value.
4) HESH does not like ERA either, but it
does tend to remove more ERA tiles from a hit face than other types of hit, especially with larger (120mm plus) shells.
5) HESH reduces concrete or brick to dust, therefore it is great on fortification or buidings removal. Hence its use in engineer tank demolition guns, and the original Burney "Wall Buster" recoilless gun of WW2.
6) HESH has a better blast effect than HEAT since HEAT is directed forwards in the main, HESH only focuses on armour that it "cowpats" against. In the game, HESH has blast effect like an HE shell of equivalent size, but less effect in the surrounding hex due to lack of fragmentation - and the blast radius is limited to 1 hex. Also the "cowpat" when it splats onto a target means that the blast effect is against the actual thickness of the steel, slope is ignored. In the game we don't have real steel thickness - but HESH ignores any angle-off multiplier effect.
Points 3,5 and 6 are why HESH/HEP was popular in the 50s and 60s.
Points 3a and 4 are why HESH has now fallen out of favour - plain steel armoured vehicles grew scarce post the late 70s (Soviet targets) and early 80s (Chobham etc for Western targets)... It is not a very useful anti-armour round any more against modern MBT and as APC armour arrays come in, them either. It also has to be fired from a rifled gun, apparently.
We don't model the other main effect of a hit with a large HESH round - the stripping of extraneous fittings like radio antennae, smoke dischargers, sights, external MG and if hit on the track area, road wheels and track plates. But then again SP does not model the fact that some shells are low velocity (like HE, and HESH, and early HEAT) - and so should be less accurate at long ranges. But then again, the longest recorded tank kill was with HESH at 5.1 kilometres (Challenger v T-72).
cheers
Andy