[US/UM] Help with shiny swapping? (Ultra Moon)

[minnienish]

So I've been using the Shiny Swap method to try and get a shiny Eevee but it's not going well. I've hatched roughly 270 Magikarp while using the Masuda method and the shiny charm. Still no luck. I've seen people using this method getting a shiny in their first batch and others not having to hatch 300 freaking Magikarp like I did. 

Here's what I did in case I turn out to be doing something wrong:

1. Saved my game before putting my French Ditto from GTS (holding a Destiny Knot) and Magikarp into the nursery
2. Walked around in circles until the lady gave me an egg
3. Got 30 eggs, had them automatically sent to the PC box for all the 'karps
4. After getting a batch of 30, took the Magikarp out of the nursery
5. Started hatching the eggs in 6 rounds with 5 Magikarp in my party each time
6. No shinies, so I threw them all into the PC and put the Magikarp back into the nursery
7. Repeated steps 2-6 until I felt my soul leaving my body

I'm the kind of person who'd do any amount of grinding as long as I can tell I'm making progress, but with this, I can't tell and I'm considering black magic as an alternative. I do have a CFW 3DS so I could easily just give myself a hacked one, but I've always wanted to experience legitimately getting a shiny. It's only happened to me in emulators and a Moemon ROM hack.