The only ones that I ever used were the duel core, soft front and hard rear 120 gr in a 25-06. They were tough bullets. I only recovered one that was shot into a deer at only 50 yards facing me in the chest. I recovered the bullet in the smashed ball socket of a ham. It was a text book mushroom and weight was 87 grs. After shooting a few deer I decided that these bullets were just too tough because deer want to run off around 30 yards. I switched to the 117 sierra and it drops them in their tracks. I still have some of the 120 grandslams for if I every get to hunt some really big deer or elk and want to use my 25-06. I have never heard of a single core grandslam. I think they are doing away with the grandslam and going to a bonded core bullet called deep curl.
Any opinions on these bullets? I noticed that Speer changed the design some years back and they are only single core now. Has anyone used them on game and how did they perform?
I think the Speer Grandslam is a very good reasonably priced big game hunting bullet. It'll never run with a Bitterroot, but that's different ball game. For elk & moose on down to deer sized game they are excellent.
I used a lot of the older 120's in a 25-06 and 145's in my 7mag.They performed great on deer and hogs.Penetration was always excellent and they smacked game real hard when it hit.I shot a doe once through the ribs behind the shoulder and when I boned out the meat,I found that the impact of the 7mag was so hard,it caused her to break her scapula!!! I'd choose the lighter weighs for deer and the heavier ones for larger game.I first started with 160gr out of the 7mag,but switched to 145's and found them to be much quicker killers.I was getting too much penetration with the 160's.I was killing them,but the 145's were giving me more DRT kills.I only recovered a couple,retained weight was 75-80% after taking out quite a bit of bone and tissue,mushrooms were excellent and no core separation.The bullet is relatively short and the B.C. isn't all that great,but I've used them out to 300yds and I cannot complain about them.