They use Rock Creek blanks.
I'm in the midst of load development with one on my Nucleus, and it's still breaking in.
Putting 65 rounds down the pipe on day one using 147gr factory loaded ELD-M produced mostly 3/4moa groups, with the smallest group (and my personal best to date) of .43moa. So far I'm quite pleased.
As I learn the science of seating depth, especially on 140gr Berger VLD Targets, it is staying about 1/2 to 3/4moa. I have every confidence that it's my loading and shooting holding me back from tighter groups currently, but I'm working on both. I just picked up some Alpha brass so I'm not relegated to the once fired Hornady stuff that I keep, and I'm shopping for better sizing and seating dies at the moment.
Fit and finish is excellent.
Tom at Go Big Tactical stocks them.