His extractor jobs have been sloppy. It should be lathe bored separately, not cut by the chamber reamer. There's not adequate relief. The throat of any chamber is without doubt the most important factor in obtaining accuracy. It's not just freebore but a combination of freebore and throat geometry that supports the bullets transition to the rifling. You want a cylindrical throat and his reamer doesn't cut one.
No amount of compensation can overcome improper chambering besides (perhaps) rechambering to a larger cartridge like 358 Win.
https://bellmtcs.com/357maxchamberthroats
