I tried using 41gr under a 150 in 7.5x55 Swiss, which is fatter and more case capacity I suspect than the 7x57.
I observed a very odd behavior. Sortuva "hangfire", or more like a click-boom, less lag than a flintlock, but every few shots would have a noticable lag.
Since I use russian Berdan primers in that GP11 brass, I can just switch to magnum primers. But H4895 and H4350 ignite just fine in that cartridge.
again, these are my 7.5x55 loads, don't use them in 7x57, but I share as an example of a BLC2 issue.
BLC2 26.0 under a 55 works fine in .223 for plinking.
try some and let us know.
shoot good
Poole
