We made some non-threaded VP9 Barrels for a competition shooter that stated the polygon rifle form has a tendency to load up with his practice rounds. I'm assuming he shoots a lot of cast bullets for practice.
Thanks @Talionis!!Nice work @bystok!
That matches the conventional wisdom about shooting cast bullets in polygonally rifled barrels @75bronco, but it sounds like he either casts his own bullets or just hasn't moved on to the polymer coated bullets. I'm a big fan of RCM stuff, and will be ordering some parts from you guys shortly, but my experience with many thousands of modern coated bullets is that they shoot really cleanly out of my VP9, and a bore snake every 1000 rounds or so leaves the bore looking like new.