I looked long and hard to find a machinist that would do that to my .308 barrel - I gave up because the only place I could find wanted more than the barrel cost.
Sounds like a dimpled barrel to me too. KAC has some freakishly bad ass setups that include them. Adco dimples barrels, and there is a member on AR15.com (SR-47) that dimples them as well. I believe that they each use a slightly different pattern.
Try DEZarms.com
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