Agreed, but most rifle grenades (according what I've read) are not...
That's true for HE grenades, but I guess a fuse detonated HEAP round will not be too useful, they need to be contact detonated...
There are several forms of HEAP.
HE Assisted Penetrator (I can't find the proper term): The oldest, to my knowledge, are an impact triggered explosion inside the base of the penetrator to give extra energy at impact. The blast is usually conical, and opposite the direction of impact.
Another form is a backwards version of HE Assisted Penetrator, essentially, it's a tamped explosive triggered on impact. It later leads to HESH. I know it was tested, I don't know if it was deployed.
SEFOP (self-forging projectile) have several variations, some of which work best detonating at 0.5 to 1.1m before projected impact. At least according to the articles I read. Note that modern (TL 8? 8.5?) SEFOP rounds can generate multiple penetration jets... either sequential (3 to penetrate Explosive Reactive Armor - 1 for the skin, 1 for the ERA layer, 1 for the armor behind the ERA), or simultaneous, for use against light armor or armored personnel. Not in the same round... but essentially, the multi-target SEFOP is a SEFOP Flechette.... Molten copper into your class II+ body armor is going to be problematic, after all. Especially if it penetrates the trauma plate by jet force, and the fiber by melting it...
HESW - HE Squash Warhead - type HEAP do require contact detonation, and delayed after impact. Most of which have an impact trigger behind the plastic explosive . HESW are best against thinner armors, where they can cause a significant spall and/or direct holing.
There are also HE Multi-Penetrator weapons, which are essentially the rocket as a single shot self-propelled shotgun dumping a bunch of AP flechettes. This generates a conical blast, rather than the more annular of SEFOP or hemispherical of HESH...
Traveller buries the complexity in abstraction.
