>>5334485>>5334485There are several canon atomic rounds. The Leeman Russ eradicator fires tank shell sized sub-atomic Nova Shell ammunition, with a blast radius akin to a larger Demolisher Canon that would just have been heavier with conventional rounds. Melta has on and off been described as a fusion reaction, and melta shells have been described as "sub atomic" in nature too. Other than that there is also the Hellhammer Cannon which also fires "miniaturized nuclear blasts".
The Dark Age have gotten even further, as archaotech pistols are also described as being capable of firing "Micro Atomic" ammunition. So essentially nuclear bullets capable of achieving critical mass and probably act like tiny bolter shells or HE bullets with a bit o' da radiation to boot.
>>5334574Point 1 I think Talos would have the mind not to make them so limited to a single shell. The Leeman Russ Eradicator carries more than one shell.
Point 2 would be a concern in a reasonable setting. But given 40k, there's a hundred examples of that type of logic just flat out being ignored. We have an explicit example of this same type of weapon with the ammunition in the Leeman Russ Eradicator. Or the Plasma Destroyer which, just like the infantry weapon, has the slight chance of exploding and killing everyone inside and around it.
In any case, 40k armies are likely aware of this, as during the battle of Vraks Krieg were known to reasonably space out their ammo depots so one bad blast wouldn't cause a massive chain reaction that deprives them all of ammunition. And if the IG are smart enough to do this, the Mechanicum Would.
Actually more realistically, if atomic munitions need to be armed they are technically safer than HE. For the same reason one nuclear bomb detonating won't actually detonate a second nuclear bomb, because it requires a precise activation sequence to achieve critical mass. The most likely solution is just scattering a lot of fissile material and radiation. But that's not even a bad thing for the Mechanicum that's just tuesday.
Point 3
Well, you could ask why the Basilisk is a thing and people don't just use more Manticores. Because even IRL MRLS systems are well, a lot more efficient at area saturation than conventional shells. IRL the main advantage of gun based artillery over rockets is ease of reloading, but that's not even true in 40k as you have the Sicaran Arcus Strike Tank which has a belt fed rocket autoloader.
One I can see for Gun Shells over Rockets all else excluded might just simply be the lack of Back Blast and being less vulnerable to direct attack, making it more suitable to be encased in armor and have the multipurpose role of both artillery and direct fire, i.e. the Vindicator Tank or IRL the ISU 152 both of which can fire their shells directly at an enemy fortification and tank as a tank destroyer, or lob their shells from a distance like makeshift artillery. Conventional Rocket Batteries would be a lot more exposed.
