If the 45 caliber Speer Hot Cores are anything like the 100gr 25caliber then you got a winner. These bullets don't come appart are very accurate and most of all very reasonable in price. I shoot them in my 257Roberts at 3150mv deer and moose don't walk away.
I never ever killed a big game animal with a Sierra bullet, along time ago I tried a165gr Sierra bullet on a moose with a 30-06 and the bullet blew up on the hide had to reload with a 220gr CIL to finish off the moose, that was the last time I ever used a Sierra bullet.