Re: 338 rum chamber question?
You should be okay in a custom barrel. We have played with seating depth in a 338 Lapua and the 300SMK is pretty forgiving. It should allow you to seat to pretty much any depth you want. Most guys are loading 92.0 grns of H1000 without issue in factory throats. Consult with your gunsmith or barrel maker and they should be able to adjust accordingly.
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