Why modding for viral sucks
Look at the radial attack. You see how it has Viral on it? You see how this build has 264% status chance? That's not even counting the +50% from [Volatile Variant] btw. You're getting Viral on your targets whether you mod for it or not. Stop modding this thing for viral. All it does is fuck up your status weighting and cripple the gun's potential.

Why [Target Acquired]
This is a separate multiplier to anything else and proc damage does scale off it. It should be noted that Gas can actually headshot so it gets more out of this mod than Blast does if you want to run that instead, though you'll have a lower Gas weighting due to not using a Primed mod and lower immediate killing capability.

Alternatives to Target Acquired

• Serration: Generic damage up. If you insist on not running Target Acquired this is a great default choice.
• Primed Bane: This is the biggest damage boost we can get since it's applied twice for our Blast, Slash, and Electric (Magnetic becomes Electric when you break overguard or shields) statuses. Banes are annoying though.
• [Vital Sense]: ONLY IF YOU ARE USING [Harrow] OR ARCANE AVENGER. This weapon doesn't crit without those. [Vital Sense] is a 60% damage boost with Avenger and a 120% boost on [Harrow]. [Harrow] is probably the best user of this weapon as he can force its crit chance to be 205% and I strongly advise using Vital Sense if you use it on him.
• [Radiated Reload]: This reduces the amount of Blast procs we get which isn't ideal. The Blast is our primary source of AoE so you want as many procs of it as possible. You get about the same damage from this as Serration due to Galvanized Savvy so it's really just a matter of if the reload speed is worth the lower Blast proc count.
• [Hellfire]: Very slightly less total damage than [Serration] but it does increase your Blast weighting.

Why [Galvanized Aptitude] on an explosive weapon
All the real damage this thing does is on the actual bullet hitting guys not the explosion. That's also why we're not modding for Heat. I don't think Heat is bad but it sure doesn't give the same degree of AoE as Gas, Electric, or Blast. Blast is the best of these choices as you can get it with just [Primed Cryo Rounds] & Heat Valence for a VERY high Blast weighting and higher base damage.
[Magnetic Capacity] is here because it's better than [Radiated Reload]. It gives us an extra status for [Galvanized Aptitude] but the status is actually useful since it's . The Mag capacity bonus also plays very nicely with Primary Crux giving us an effective 45 round mag. +14 mag size > -0.7 reload time

Why Crux instead of Deadhead
You cannot get 300% Status Chance and 60% ammo save from mods. Meanwhile you can get 320-480% damage just from Galvanized Aptitude.

Why not [Semi-Rifle Cannonade]
Can't boost fire rate if we use that mod and I personally think this gun fires way too slow for that. Also the punch through is wasted since we already have 3.6 with other mods. I did test out a variant with it and it's not awful or anything. It's a 49.9% damage per shot boost, but a 26.7% total DPS loss. Another issue is that the best non-bane replacement for [Vile Acceleration] is [Radiated Reload]. I don't like it personally but it's not like this weapon is locked down by Forma so you may as well try it both ways to decide for yourself which is better.

Why [Vile Acceleration] instead of [Primed Shred] or other fire rate mods
We're already at 3.6 what are you shooting that you need more punch through than that for? The 90% is very nice and you're never going to feel that -15% off of Savvy (& Serration's if you run it) 485-645% damage.