Back in the late 80s / early 90s as a student at UF I used to use these 50' Kodak mags in N-6 type GSAP gun cameras for skydiving. Got a simple jig from the late Jesse Chambless to spool off roughly 50ft onto the little plastic cores, then I'd just load the mags myself. Eventually I added a 2nd "hole" into the jig so I could spool off 100ft darkroom loads for my N-9 mag. The N-9 was a completely different gun camera system than the GSAP.
Anyhow the 50ft Kodak mags aren't all that hard to load. Just gotta be sure the "ratchet" mechanism on the pressure plate isn't busted off. In a manner of speaking it acts as a sort of reg pin. The claw in some magazine cameras fully disengages the perf before travelling back up for the next frame. But in others, for instance the Bell & Howell Type N-6, the claw is basically a wedge....camera only moves it up and down, and it engages the perf via spring pressure. If the "ratchet" bit on the pressure plate is busted off, the claw on this type of camera will move the film upward in the gate during exposure.
So if you've got some empty Kodak mags and some spare gun camera type cores, it's a plausible idea to load / download them yourself, have 'em developed at Spectrum and have the lab hold onto your cores. They'll do Ultra-16 for a small upcharge.
It should be noted that the Kodak mags are mostly pretty simple pressed metal. It's not the precise machining you'd find in an Arri or Aaton or Photo-Sonics magazine. To my eye, some of them are just gonna scratch.
The reason I say "to my eye" rather than "in my experience" is because I only have experience using two labs for film shot those types of magazines -- the long since closed Jernigan's Motion Picture and Video Service in Gainesville FL, and Continental in Miami. Jernigan did my Plus-X and Tri-X Reversal. And guess what? Film was often scratched, had uneven density, had intermittent bleach spots and veins, and frequently had dirt & dust at the head & tail. I didn't know any better at the time. Now while that would be appalling for a modern lab to put out, I kinda wish I'd taken advantage of it back then....would've been great for music videos. Maybe the drifting density and bleach spots are something b&w reversal film is more prone to than neg?
Earl Jernigan's lab was left over from when tv news segments and UF football games were shot on film. I learned quite a bit from Earl in my formative years about how motion picture labs function. As an aside, I didn't know at the time that Earl was Tom Petty's uncle. Found that out shortly before graduating. It was pretty cool decades later when I was working with Tom on the Runnin Down a Dream documentary being able to share stories with him about ol' Earl. Dude was genuinely and pleasantly surprised when I dropped his uncle's name!
All that said, I imagine that at some point next year I'll pick up some 2R film at FPP if I can't source it locally. Likely develop and maybe even scan at Spectrum, particularly cuz FPP's turnaround time seems more for hobbyists than pros.
