As correctly discribed, its a 338 wildcat based on the 408 CT parent case. Unlike all the others based on this case however, the shoulder location is moved forward to increase case body length and capacity.
My accuracy load with my current lot of H-50BMG is 144.0 gr under the 300 gr SMK good for right at 3300 fps.
Some of my customers are pushing the throttle to 3400 fps with this bullet with decent case life. I have tested the 265 gr bullets up to 3500 fps with well under 1/2 moa accuracy.
Dies are available from me with rifle orders as is fully formed, correct headstamped brass. Single shot and repeating rifles are available. These are large rifles in the 16 to 20 lb range for most of them but they take long range shooting to a very distinct, next level up over all other conventional 338 cal magnums.
There is also the 375 Allen Magnum, same case design just necked up to 375 and uses the 350 gr SMK loaded to 3250 to 3300 fps.