Monday, June 25, 2012

50BMG: How good are they really?

I hear a lot about just how strong a 50BMG is. I wanted to know just how true all that was. So we pitted a 50 BMG, a 7.65x53 mauser, and a 5.56x45 AR-15 against a steel plate.

At ~700 grain the 50GMB is heavier than the 63 grain 5.56 and 174 grain 7.65. The 50BMG is firing out of a 29" barrel for a solid 2,500 ft/s vs the 2,460 ft/s of the mauser. Here the 5.56 scores better even out of it's 16" barrel at ~2,900 ft/s. That puts the 50BMG at ~10x the power of the AR and about 6x the power of the mauser.

For this test, we only have solid lead shot for the mauser but we've got basic (non-explosive) armor-piercing ammo for the 5.56 and 50BMG.

... and we have a 1" (~25mm) thick mild steel plate. Getting a hardened steel plate at this size would cost ~$300 and so we'll test hardened vs. mild steel with some smaller rounds and cheaper plates. I actually suspect hardening protects only slightly better or not at all better but does have the property of being all-or-nothing. That is a hardened target will be either totally broken through or shrug off the round entirely, while a mild target will get ever larger craters until it's broken through. But I digress, and we will have to test that.

At 100 yards, the 7.65 with solid lead makes only a 3mm crater in the steel. The 5.56 with armor piercing steel cores makes a 4mm crater. The 50BMG with armor piercing steel core is so close to passing through we can see the hardened steel center of it pushing ~1.5cm through the back of the steel plate.

It makes a big difference. But if anyone ever says a 50BMG can shoot through a tank, remind them that the purpose of tanks is to have rifles not be able to shoot through them. Modern tanks sport more than 100mm of composite armor.

Photos courtesy of our excellent friend who goes by the name 'Chris' until he comes up with a better internet alias.

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