Shaped Charge vs Explosively/Self Forged Projectile

[MrDakka]

What's the difference between the two?

From what I understand, the concavity/shape of the liner (and thus the shape of the explosive) is what determines which is which (shaped charge uses a conical liner, while the EFP uses a dish shaped liner).

Therefore the geometry of the liner and the explosive causes the two different effects.

Am I correct in my understanding?

[mrtspence]

Yup. The geometry is everything for determining the parameters of the projectile. I don't remember the formula off the top of my head, but a wider dish shape makes a shorter, more aerodynamically stable projectile while a narrow cone makes a longer, less stable projectile that penetrates armour much better.

I'm not sure where the distinction between the two is drawn, but it is in there somewhere!

[Sea Skimmer]

While you can make a range of shapes between a normal shaped charge and an EFP, in reality the line is generally easily drawn because the intermediate shapes just don't make sense for much of anything, and results can get very erratic. Either you want serious standoff, and make a full fledged EFP, or you want maximum penetration and make a normal conical shaped charge. Though it is worth pointing out that the most advanced shaped charges do not have a constant angle of cone, and additional wave shaper layers set within the explosives become important to wrapping the explosive shockwave around the liners evenly.

The only major exception I know of are flying plate warheads, at times called explosively driven impactors. Basically this is what it sounds like, you sort of have an EFP like dish shape, but even shallower, and the entire thing is simply blown off as a plate, without serious deformation, into the target. The main reason to use this kind of warhead is to blow a large diameter hole in concrete. However a similar effect can be accomplished by making an EFP liner that has dozens of small EFP cones within it, basically hitting the target with a hail of closely projectiles, and this way you still retain a higher degree of penetration in armor plate and much greater effective standoff. End result is a flying plate isn't very versatile, so they aren't used for much. So far neither are multi liner EFPs because the ability to economically manufacture them is somewhat new.

In general what you can think up in terms of shaping conventional explosive blasts, will work. They respond well to external pressure and contact the way's you'd hope they would. The problem is making them so do reliability, lot of that is just ensuring precision in design and manufacturing under a range of environmental conditions, and with high efficiency which is largely trial and error on the firing range.