Hi Bob,
OK so 100 - should have eased things in really. geogia arms ammo - no idea, never tried it. CCI Blazers - well have shot a few, I think without probs but really don't remember.
Interesting tho - the CCI Blazer SD ammo - in aluminum cases, in fact uses the Speer GD bullet and performed well for me - OAL on those is generous like the GD's themselves - around 1.124".
Dirty gun could indeed be a factor - I have shot approx 70 as a max before cleaning, never 100.
Low S/N eh - well that I guess would make it a Farmingdale with blue grips - frame?, hmmm .... possibly a grey but could be an early silver?
My first R9 is 32x - no prefix - so later than yours it seems but maybe not much. My second one is R30x.