yes, the 350 gr SMK was made specifically for Chey Tac Industries and Jamison International are the ones taking care of distribution.
In my testing, BC seems to be in the .770-.780 range. Pretty close to what Jamison told me which is really close to what Sierra lists the 300 gr 338 SMK BC at.
As far as this bullet in the 375 RUM class chamberings. I think it will work fine, expect your velocity output to drop, perhaps more then many would expect. Also realize that the 375 bore diameter is not overly barrel length dependant so throwing more barrel length on a rifle WILL increase velocity but as the bore diameter increases, the increased velocity per inch of added barrel length REALLY drops off.
That is a minor downside, the good side, this caliber does very well in shorter barrels!!! ITs a relatively high expansion ratio bore diameter which allows faster powders to be used and there is less baring surface on the bullet to the bore. Some feel its simply the larger area at the base of the bullet, whatever it is, the 375 will do very well in shorter barrels.
When talking about even heavier bullets, I personally feel that the ballistic advantage of a 375 to 385 gr bullet in 375 will be wasted to some degree in chamberings such as the RUM. The reason is simply the velocity potential will be limited so that the lighter bullets will likely do just as well if not better then the ultra heavy custom bullets that may be coming on the market soon.
They will certainly work and velocity is certainly not the end all of ballistic performance, that is for sure. Wind drift is the real killer and that will be an advantage of an ultra high BC bullet but again, I believe anything much heavier then 350 gr is getting pretty big for the RUM class chamberings and smaller.
One example of this, I tested the 300 gr SMK against the 350 gr ULD RBBT in my 338 Allen Magnum. Because of velocity advantage, the lighter bullet had better ballistics out to around 1500 yards so if your not going to be shooting past 1500 yards, there is really no advantage for either bullet.
I feel it may be the same in the 375 as well but I really want to get my hands on a 385 gr class bullet in the 408 based wildcats.