I hear tell, that GS is coming out with a 270 gr LR hunting bullet soon in the .7-.8 range. How soon, I don't know. Cutting Edge also has a 275 gr bullet that they advertise with a .76 BC @ 3000 fps with. If in fact the BC's are accurate, that gives them an equal BC with less mass, which means more velocity and better LR ballistics.
I've been working with both the GS 177's and CE 180's in my 300 RUM and I don't have any conclusive results yet, other than both are giving better velocities than the conventional bullets. Initial shooting shows the GS bullets are giving me the best velocities and the CE's are giving me the best accuracy as far as I can tell at this point, but I need some more trigger time to sort it out better. At present, I'm shooting these out of a factory barrel. Hoping to be shooting them out of a custom before long.
About the LR GS bullets... They have a very long nose and the ogive is a very short distance form the brass mouth, meaning... a short throat is probably best IMO. With the CE bullets, the throat length may vary depending on which form you use.
For max effective range based on "minimum expansion velocity", according to the ballisitc calcs, my 300 RUM shooting the GS's or CE's will significantly out distance the the 338-300 RUM shooting the SMK or Berger. The 338-300 RUM or 338 LM will arrive down range with more momentum and KE shooting the cup and core bullets. Windage will be close, and drop & TOF will favor the lighter faster bullets.
Ain't this fun