I'm the similar, I've turned in 3 and I am rank 2. It might just be coincidence, but I did notice that I found my three on separate locations. One on Earth, Mars, and the Dreadnaught. I wonder if it's spread out one per planetary location?

This occurred to me as well. I don't remember where I found mine, though :(

Just random, I found 2 with different numbers, both on the Undying Mind strike (different runs though).

I'm the similar, I've turned in 3 and I am rank 2. It might just be coincidence, but I did notice that I found my three on separate locations. One on Earth, Mars, and the Dreadnaught. I wonder if it's spread out one per planetary location?

This occurred to me as well. I don't remember where I found mine, though :(

The article is mostly junk, but there's one thing the guy is missing. Earlier, I read speculation that you could only get one of the fusion rifle turn-ins per gunsmith rank. I've yet to see anything disproving this, and i've found 3 of them to date (gunsmith rank 3 here), so it holds up to my anecdata. It's possible that you need 5 of them and the very few rank 5 gunsmith people just haven't found their 5th fusion rifle turn-in yet.

Like BlackT1g3r, I've turned in 4, and I'm rank 2.

EDIT: Confirmed you can get as many as 4 by rank 2. My theory is debunked.

You have to skip to the bottom of the article and look at the tweets he tweeted.