Chuck, we talk about chokes, not bores. With 600 paper I will "wear" choke for .001 in one minute.
I guess nobody saw worn modern guns here. 100, 200 thousands rounds that's OK, but 500 thousand or 1 million - I fix (honing) several sporting guns with colossal run and all of them got some issues with cones and pre-choke areas.


Geno.