If it was an RPG projectile, I doubt it was the usual PG-7VL shaped charge grenade. The Abrams has faced them for years, they're a known quantity, and the tankers involved can be reasonably expected to have been very familiar with the effects of the RPG rounds on tanks.
The improved PG-7VR dual-charge rocket used for first detonating reactive armor, then driving the second charge's blast through the armor is possible, especially if the first charge had been disabled or combined with the second, as unneeded since no reactive armor was present of the Abrams.
And there's another, real scary possibility: what if someone has taken the principle of the hypervelocity LOSAT round and applied it to an unguided HVAP kinetic energy round for the RPG7 launcher. Especially if used to drive a saboted penetrator, such a round could be really bad news for Abrams tankers.
-archy-/-
