These feed and function in Wilson 15-twist 300 Ham'r:
RCBS 7.62-130-SPL
ACC 31-142-FN
NOE 309-146-SP
NOE 311-152-SP
All were GC'd and PC'd (Smoke's clear).
I have no notes on accuracy, although they all hit paper. These were for F&F testing last year. I need to get back on this project.
As mentioned above, chamber and throat is tight, and that presents a problem in cast bullet selection. Throats in 300 BO can be similarly short, too.
Cast bullet load data is severely lacking. Get that last round from the mag to fully lock BCG back and then start running them across a chrono and mark where the brass piles up during load development. IIRC case capacity of the 300 Ham'r is about 95% of 7.62x39 - but don't hold me to that number. That is how I began to develop some cast load data that worked. DO NOT take that 95% number as gospel - test for yourself. There is a fair bit of 7.62x39 cast data available to work from.
Also if IIRC the 300 Ham'r case body is slightly blown out, so use fired cases to test usable powder space. I bought cases, because I wanted them properly head stamped. I made my own 7.62-40WT cases from LC 5.56, and they work just fine, too.
Personally, I like the 300 Ham'r. The 7.62x40WT (12-twist) is not bad either. Both of these were designed to be supersonic from the gitgo.
Just in case you may wonder why I have both, I had the 7.62x40 long before the 300 Ham'r. Then I hit a really good sale on a 300 Ham'r barrel, and the rest as they say is history.