Almost anywhere you go on the internet and read about guns used for combat or defense you will find the guys who will tell you that to kill anything bigger then a cat, you need the .308 . Often this is followed up with the smarmy little quip, “308 turning cover into concealment since 1953.” The problem with this is that it is not exactly true and the 308 is hardly the tank killer its more rabid fans make it out to be. The war on terror is often used as proof of the 30 cal rifles being better then 556. What they do not mention or maybe don’t know, is if a 556 wont penetrate a brick wall, a 308 probably won’t either.
I took my 308 out to do some testing after hearing that old chestnut about cover etc. one too many times. I have shot at a lot of stuff, with a lot of stuff and seldom have seen the performance claimed that a 308 will give. I set up a little wall of cinder blocks and put a cardboard target behind it and backed off about 75 yards. Then fired a few 7.62 ball rounds at it to see what got through.
The blocks did not even have all the other things associated with a normal house mixed in. No pipes, or wiring or paneling or drywall. this would be an advantage for trying to penetrate the wall since it would have nothing else to get in the way. So, according to the 308 boys club, the round should have zipped through and exploded the target like an A-bomb.
The block cracked. But the round did not go through and destroy the target. It took three rounds to do this. Nothing that hit the target was even close to lethal. Just a few pieces of block. Keep in mind, this is from not very far away and was block only. None of the other things that make up a wall in a dwelling or some other facility that would have insulation, Wiring and pipes adn who knows what else. Increase that yardage to 200-300 yards and beyond and the performance would drop even more. You could turn the cover into some thing less then cover, but it would almost take up your entire mag.
The 308 is an effective round. But, it weighs more. costs more, recoils more. is harder to shoot then 556. Needs longer follow up, the guns are heavier , slower and louder then a 556. Think long and hard about these things along with what you really need your rifle to do before you buy a 7.62 rifle based on what some will tell you about its magical unicorn stopping power. It is a potent round, but it is not what some make it out to be.
To add to above, I was reminded by Mark Hatfield that the effectiveness of the 308 or any round for that matter on blocks, is lessened even more when the block are set by real masonry. Blocks standing free will break apart and give the round a more impressive look that does not reflect reality when trying to shoot through a real wall.
The picture above is a small structure that housed a pump for a well. It was made after the main house was built and was constructed in the exact same manner as the house walls. The holes in the picture are form a 308 shooting M80 ball from less then 30 yards. Not one of the shots penetrated the blocks. Hardly the godzilla destroying power internet experts will tell you the 7.62 NATO has.