(Pardon for not paying attention to that angle).
An on-topic discussion with inconclusive results:
(Note: if half the commenters say one thing, and half the other,
I'm not gonna pretend there's a lead-pipe cinch panacea in there for you).
A member of the polish-American community finds lead shaved off the bullets,
and polishes lots of stuff:
Another folk theory they've got is to disassemble their rotary magazines,
and reduce the preload on the torsion spring.
If you can count and you're meticulous, at least that's a reversible hack.
But, lots of the standard QC whinging in that thread,
don't click until you brace yourself to avoid buyer's remorse.
Did the failures to extract occur pretty much from the very beginning,
or did they become more frequent over time? Ramping up implies
a crud problem, or a wear problem that appeared scandalously quickly.
OTOH, steady-state lends credence to the dimensions of that specific rifle.
Also (and pardon if you already said), does it extract unfired rounds
from the problematic ammo lots significantly more reliably?
That also lends credence to the cases bulging just enough.
If you haven't tried that, maybe remove the firing pin
(so you don't have a Living Room Pop) and then spend
some time racking a few mags of live ammo through the action
and keep tally of the extraction failures (if any).
(Don't let a half-ejected round get crunched by the bolt - zing!).
