My sampling of the GS is small, several deer and a small bull taken in the early 80's. I found them to be tough and never recovered any, all had passed through the animals. I loaded 180's in my father's .308 in the early 90's and they expanded greatly on a 250yd shot. They seemed much softer than the earlier ones. The earlier 130gn. .270 bullet was very accurate but some time later they must have tweaked them, a later purchased box of 130's had the cannelure moved more to the center of the bullet and they weren't as accurate. I believed they also advertised a "ring?", similiar to Hornady's Interlock. Yesterday I purchased a box of 150gn Grand Slams for $9.97 at a local Sportman's Warehouse. The box had been taped but seemed intact. That's cheaper than what I paid for them 30yrs ago. I also paid $19.97 for 140gn .270 Federal Trophy Bonded bullets, are these new bullets not selling well? That seems very inexpensive for a premium bullet.
