I've used an ELDX on a deer at close range. Velocities were moderate, weren't too fast, magnum-like. It pretty much performed as any other conventional cup and core bullet would have performed. It hit a rib and blew up. The deer died in place, though. So it did what a bullet should do. I think the bullet performs better at lower velocities. My inclination would be to go for heavy for calibre weights and moderate velocities. The faster the intended velocities, the heavier the bullet, twist rate permitting. My experience is that they can be very accurate. My 65CM shoots them into a ragged hole. Another rifle also shot them very well. I have no experience with the Sierra GC but if they are like other sierra bullets I've loaded, they'll shoot just as well. I've found Sierra to shoot well in a variety of rifles in general.