I did run into the same issue when I made my Legion Flambard Special Weapons Tank (stand in for the legion stormblade).
The problem I see with going the volkite-grenade route is that it calls for a "standard" cannon or a linear massdriver, not the destinct visuals of a volkite beam-weapon.
The solution here is to invent a whole new subset of Volkite Armaments of the Teleac-pattern: weapons that, rather than projecting a focussed beam of themodynamic energy induction, creates an area-saturation effect by using partitioned beam-emitters within the weapon that crosses the multiple individual beams at the target location in a staggered sequence a few nanoseconds apart; where the intersecting forces blows out in a spherical blastwave of thermodynamic annihilation. As this mode does not create a focussed beam active for perhaps a second or two there isn't much need to shoe-horn in the Deflagrate rule as without the focussed beam, catastrophic overpenetration of the target(s) does not occur.
"Volkite Annihilators" perhaps? Then added to the existing class-size, so the battlecannon becomes the Telerac pattern volkite Demi-Culverin Annihilator, the stormhammer cannon (and similarly sized) becomes the Teleac pattern volkite Chierovile Annihilator etc, etc.
Perhaps we can think of a better name than "Annihilator" though...
Edited by STC Logisengine, 27 December 2016 - 07:10 PM.