A 150 gr. 308 bullet will blow through 1/4" steel, regardless of the bullet construction. My 6.5x55 shooting a 140 grain Sierra GK (soft nosed bullet) will blow through 1/4" steel from 450 yards. This is the farthest I've tested it. I doubt your bullet blew up, and I can also tell you that a 30/30 would not have been any better. You were either trying to shoot through a tree trunk, or flat out missed. Here's an interesting test on bullet deflection:

http://www.theboxotruth.com/docs/bot40_2.htm