Hi all,
I recently acquired a new KUSA KS-12. I figured I would post the break-in process. I lurked on this forum and it was really helpful, so I figured the least I could do was relate my experience on this process.
OUT OF THE BOX TESTS
Everything was run on gas setting 1 with the same 5 shell OEM magazine. Here is the breakdown:
Winchester X slug - cycles cleanly (1600 fps)
Hornady Critical Defense 00 - cycles; one stovepipe... could be used error.

(1600 fps)
Hornady American Gunner Low Recoil 00 buck - does not cycle (1350 fps)
Remington Express 00 buck - does not cycle (1325 fps)
Federal birdshot 3 1/4 dram eq - does not cycle
I communicated with KUSA and they said run it on 2 and break it in some more. I put it on 2 and ran several hundred hand cycles (saw that here). I sparingly added light oil to the rails. It now will cycle all of the ammo above, even the bird shot.
My final step will see what cycles when I put it back to gas setting 1. If it cycles the Remington 1325 00, I will be satisfied. Changing the gas valve to 2 for bird shot is not a big deal to me...but it would be nice to "set and forget" on 1 too.
Thanks for reading.
Toku