I am not familiar with this cartridge, but if it is formed from 444 brass, and they left you with a .277" neck, I am guessing they are after max case capacity. I would say it's not ideal as far as rough handling of ammo is concerned, but will probably be OK., providing you have enough neck tension. i have loaded lots of rifle rounds with not much more bullet in the case, but none with this heavy of a bullet. I'd load some, and try to twist/wiggle the bullet around. This will give you an idea of how durable the loaded rounds are. They may be better than you think. It sounds like you have what you have, and if they won't take rough handling, you will have to take steps to prevent damage to them. If it's mostly a range gun, no problem, if for hunting, you may have to find a stiff holder of some sort to carry spare ammo. With a 270 gr 375 cal. bullet in a 444 case, you'll probably only need 1 anyways!
