Sorry for the intrusion, I normally just lurk around here but you are talking about my two favorite cartridges.
I have had a 7.62x40WT since 2011 and it has been my constant companion, and handled everything from beavers to bears. Then Bill Wilson started working on the 300 HAM'R! Knowing how I felt about the 7.62x40, he allowed me to follow along from day one and it has been an interesting adventure.
Please allow me to answer a few questions that have popped up. AA1680 worked well in several loadings and Shooter's World Blackout is almost identical. However, CFE-BLK had shown more versatility with lower pressure levels. Shooter's World SOCOM has also worked well in some loadings. Forming brass is similar to the 7.62x40 process and is easy enough to do. In fact, I just finished a batch of 5,000 rounds (all Lake City) a few weeks ago. If you don't want to go through the process, Starline and SIG have both produced brass. To date, more than 30 bullets ranging from 110 to 150 grains have been tested for the 300 HAM'R.
I always found the 7.62x40WT an accurate round and the 300 HAM'R has given me the same (and better in some cases) accuracy.
If you want to shoot sub-sonic you can stay with the 300 BO but for pure power, the 300 HAM'R is the ticket. The best thing I can say about the Blackout is magazines designed it will work great with the 300 HAM'R.
The bottom line is, all you need to change on an AR to convert to the 300 HAM'R is a new barrel. You can convert 5.56 cases and maintain the standard capacity that you would have with a 5.56. I have fired thousands of rounds during the testing process and have not had a single problem. (OK, I did have one primer inserted upside down but that was my fault.)
If you are wondering about "longevity and availability" just hang around for a while. I promised to keep my mouth shut but 2020 is going to be an interesting year. I have no ties to Wilson Combat other than friendship, but I have reviewed the 300 HAM'R in several magazines. Today I can say that there is no "hype" in Wilson Combat's statements about the 300 HAM'R, it is the real deal!
