Borrow someones RCBS Auto-prime. The one that uses the APS strips has a universal shellholder that works on just about anything short of 50BMG. It's what I use on 7.5 French (and about everything else).
Also if you know anyone with a Bonanza press it to has a universal shellholder and you could use it's priming attachment........DJ

Mike the rim diameter and thickness and compare it to specs of other cartridges in the manuals. You should be able to find a close match to order a shellholder for. Pay attention to the extractor groove but you may have to settle for one with insufficient rim clearance and need to grind the top of the shellholder.

The RCBS #2 shellholder should work (Lee states their #3, but you found out differently).



As for the CCI #34 primer, that is a thick-cupped NATO primer, and may be too much for your brass (check your brass to make sure that any remaining primer crimp has been removed). Try a regular old large rifle primer.

I am trying to prime some new French 7.5 brass using CCI 34 primers and my Lee auto prime. The Lee instruction sheet doesn't list a shell holder for this cartridge. I tried the no.3 shell holder which is listed for fitting the 7.5 Schmidt. The primer wii not seat; it feels like it is not
centering the primer in the brass. I tried the remaining
10 holders in the shell holder kit with no luck. Any ideas?