What you say makes sense. I noticed the shallower rifling in my 1917 with a 2 groove barrel. Bore passes the bullet test with ease but it simply looks worn when it probably is not, just when compared to the deeper rifling of other nations.

So Germanyicon in WWII was using non-corrosive primers?

Japanicon also chromed a lot of their bores so that would lessen the impact of the corrosive primers.

It would seem on the low side for a barrel to only last 3000 rounds, that's probably my biggest question to your explanation.
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