I tired, a 300 BO round is too short to head space correctly in a HAM'R and won't fire. I don't think a 300 HAM'R will even close the bolt in a BO.
Right now, Wilson Combat is your choice for barrels, but a lot of people are looking at this cartridge and that could change at any time. Personally, I choose WC barrels for all of my AR projects. They are reasonably priced even when they aren't on sale.
Yes, a 125 gr. Nosler BT will work well in the 7.62x40WT. I have used that bullet in one of mine for years. I have been a fan of the 7.62x40 ever since WC brought it out. I will always keep one for sentimental reasons but it sees little use since I've started shooting the 300 HAM'R.
