Case length is the same as x47.
It's standard magnum BF and it could be formed from SAUM if a guy wanted to do all that. We already have guys that want to and will take good notes on process and prep.
Good news is we will price ready to fire brass, reamers, and dies as affordably as we can - no holding your wallet hostage.
It's not intended for strict tactical match guys. It's a crossover hunting-match round with as good geometry as you could ask for.
If you want to load it down to 2970-3040 fps where the 131 ACE likes to run it will do that without a hitch. If you want to roll 3140-3170 it will hum right beneath PRS speed limit with low recoil and a killer BC for longer, windier matches like Q Creek, Nebraska stuff, and some of the longer western venues.
The next bullet we release will absolutely scoot out of the 257 Blackjack case. The third BJB release will fit in a 2.880" mag as well but have enough power to get it launched at respectable speed for full effect.
When we do official release there will be a handful of 6 BLACKJACK reamers for guys to crank on as well as the PILE of 257 Blackjack reamers.
Over the next few months we'll start a new thread for 257 BLACKJACK to keep everyone in the loop.