When trying to convince someone of anything, it's a clear advantage to speak in concert with observable facts. The barkeep hears Phil at about the same time as the crystal grenade blows apart a section of his café - and the shotgun swivels in response.
Spoiler: Barman
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BS: (1d100)[73] vs 32 +10 for aim, +10 for short range
Damage: (1d10+4)[13]
He acts on Phil's initiative, meaning after the enemy takes his action this round.
Oh, on a sidenote: Shotguns are still Primitive, so long as they are black powder weapons - as this is. There is no modern, 41st millenium era gunpowder on this planet. But ... I mean, who knows, maybe those crystals can be used in firearms too? Hard to say, no?