I shoot 6bra, 6gt. I have been able to get both rifles to shoot 10 shot groups in the 3s pretty easily. I feel the 6gt is more adaptable with its larger capacity. It can use more available powders VS the bra. I've had success with varget, N150, H4350, rl16, ts15.5, N555, n550, with 105-115gr bullets. I usually run 109 Bergers or 115 dtacs in the gt case. 105s in bra with varget or 4166. I've shot some extremely small groups with both cases. I think the bra might be a bit easier to tune, 30.5-31gr varg with 105hyn 30-40k jump has been a sub half moa load in 2 barrels. My very first barrel had longer freebore and I used 33.4gr H4350 with 105s at 2930fps and it shot incredibly well, but that was a very fast lot of H4350, wish I had more of it! Alpha bra brass(which I'm using) has issues, fireform lapua and ensure you have a properly specd reamer if you go this route, harrels makes good dies, D3 is pretty standard. The gt is simple, pick your freebore for the weight class of bullet desired to run. Load 35.4-36.7gr H4350 with a quality match bullet seated 30-50k off, pick the powder charge that shoots best at 100y. Put it on paper at 500y to confirm, go have fun.