It would be interesting to hear JJ's opinion. Is it possible that someone tried to cure a sticky extraction, perhaps caused by crappy brass, with a hone?

Could there have been some corrosion in the chambers from the old Kynoch that someone tried to clean up

Would anybody do such a thing?

I really wonder who loaded the ammo that was sent along with the rifle. With one case 4 grains different could quality issues enter in?

I also don't understand why it would take a year to sleeve the chambers, backlog?