Yeah so it turns out no one knows wtf they're doing making "archon 1 shot" builds for this weapon either, so I just used what I know from making my Kuva Hek archon 1 shot build to make one for this thing too.

First off, the evolutions.
1.) N/A
2.) Attuned Accuracy. Usually Frictionless Flight would be a better idea but we use this instead to make it easier to land all our pellets.
3.) Dual-Mode Chamber could be taken for the extra projectile speed if you want a comfier max range, but it really doesn't matter.
4.) Wracking Wrath. Crit chance needs to be as low as possible to synergize with our 5th evolution.
5.) Devastating Attrition. This is a 50% chance for each pellet to deal x21 damage so long as they don't crit. If you don't want to use this evolution then don't bother bringing this gun to an archon fight.

Now that we have the evolutions out of the way we can get to the important bit that drives me nuts seeing everyone else do, you do not run [Galvanized Savvy] on an archon 1 shot build. It doesn't work. You need to hit the archon first for it to provide any extra damage and at that point you are not 1 shotting and also causing archon damage attenuation to scale making it HARDER for you to kill them when you do fire. Sure you can make a solid build with Savvy but if you claim its a 1 shot build I'm calling that false advertising. My builds actually end the 2 phases in one pull of the trigger each which is what a real one shot build should do.

Archons have Alloy Armor which is weak to Radiation (75%), Cold (25%), and Puncture (15%). Weaknesses for armor are special in that they double dip in effect. First they ignore that percentage of armor, and then they increase your damage by that percentage too. So for Radiation an enemy with 100 alloy armor is treated as having 25 armor and then you also get bonus damage on top of that. This is why we build for so much Radiation & Cold.

I've checked a few variants of the build and determined [Vicious Spread] is weaker than [Scattering Inferno] (or [Shell Shock] if you have it). The numbers on this site will appear higher, but in game the Radiation weakness of the armor will result in [Vicious Spread] being the weaker of the 2 (technically 3) choices.

We run Primary Deadhead because it's easier to maintain the on kill damage bonus and the headshot bonus helps us hit a little harder. You are required to headshot for this to kill in one hit anyway.

As for the frames, I advise running [Revenant] since he doesn't mind building 300+ Strength to get the highest boost out of [Xata]'s Whisper. He also won't die while you line up the shot.
You could use [Ivara] and abuse her massive headshot damage boost while in Prowl alongside [Xata]'s Whisper if you wanted to (or if you need to because you don't have the 2 Primed element mods) but this will require you to forma this gun a 7th time so you can swap the Exilus mod to [Hush] or it can't get the Prowl headshot boost.

If you mess up your shot and don't kill, wait about 30 seconds while damage attenuation decays, then fire again.