"Effects that reload while holstered (such as [Eject Magazine]) will restore ammo without affecting the previously thrown blades, which will return upon normal reload, resulting in a higher amount of blades that can be generated and then returned simultaneously."

"Once the amount of embedded blades exceeds 30, older blades will begin returning with each shot in an inconsistent order."

"This amount includes shots produced by Multishot."

Warframe Wikia

ARCANE PISTOLEER IS MUCH BETTER AT THIS THAN [Eject Magazine] HOWEVER

"[Synth Charge] will affect all returning blades if reloading from empty." (Warframe Wikia)

Seeker does benefit the gimmick a lot. But you can always replace:

• Seeker > Primed Pistol Gambit
• [Eject Magazine] > [Lethal Momentum]

Note that [Lethal Momentum] is tied for the best exilus mod with [Eject Magazine] due to the increase travel length of the knives. Longer range goes a long way for the punch through. The [Eject Magazine] strat requires a pretty long setup, so if you don't want to dabble with a long setup for the 30 knives to hit enemies on return, use [Lethal Momentum] and contemplate if you find it worth to spend an Arcane Slot on Arcane Pistoleer instead.

Secondary Merciless can be replaced with Cascadia Flare for more damage since the gimmick already gives some reload speed, purely optional though

Playstyle

Normal gameplay

1. Try to throw knives at enemies when they're lined up
2. See the red crits

Arcane Pistoleer strat

1. Let enemies form a conga line
2. Throw knives with punch through at enemies' heads until you get a headshot kill
3. Throw knives with punch through at enemies when Arcane Pistoleer activates
4. Repeat step 3 until 30 knives are out on the field until knives forcefully return to you
5. See the red crits like they're fireworks as they 'punch' through all the enemies in the conga line
6. Repeat

[Eject Magazine] strat

1. Let enemies form a conga line
2. Throw knives with punch through at enemies
3. Switch to primary or melee and wait for passive reloading of all of your knives
4. Repeat steps 2-3 for 5 times until 30 knives are out on the field
5. See the red crits like they're fireworks as they 'punch' through all the enemies in the conga line
6. Repeat