James and I got together to test penetration again. He brought some of the old toys, and I brought some new ones.
This time the brake discs were from a 2005 Mazda RX8, which is a sports car, which means the brakes are bigger and badder than the ones we shot last time, which were from a Toyota Tercel. As you can see, if the bullet hits one of the fins between the layers, it faces one inch of steel. If it hits a void, it has nearly 3/4 of an inch to punch through.
We used James' TPD AXR (5.56x45mm NATO), Cugir TTC (7.62x25mm), and Steyr M9A1(9x19mm). I brought my S&W Model 64-3(38 Special), Cugir TTC (7.62x25mm), and Yugoslav M48B Mauser (8mm Mauser). The rifles were shot from just over 35 yards, and the handguns from 10 to 15 yards. Ammo varied, and I'll get to that later.
First, the AXR launched a Remington 55gr FMJ lead core (left) and a PRVI Partisan "green tip" 62gr steel core. The lead core seems to have shattered on the first thickness, hit a fin, and stopped on the second layer, but cracked the back of the disc. The green tip (two shots shown--right and center) punched cleanly through the first layer, and one steel core made it out the back while the other ricocheted.
Then I brought out the Yugo with some Romanian surplus 8mm 150gr steel core from the 1970s. It very nearly did what I thought it would. It sliced through the first layer, then smashed through the second. The surprise was that the disc stopped the steel penetrator, and we found it amongst the wreckage.
Cool, huh? Remember in that "What's Bulletproof and What Ain't" article I posted a while back? This is why I said that if you're taking fire in a parking lot, you should get behind the engine block and align yourself with the wheels. Remember that this bullet didn't make it through the brake disc, and would have had to punch through a wheel rim before getting there. Okay, ego massage complete, moving on.
I then had a go with my S&W 64-3 shooting 125gr lead flat point handloads. They did exactly what I thought they would, shattering on the first surface without doing any damage at all. Moving on.
Then James had at it with his Steyr M9A1 shooting some kind of cheap 115gr FMJs. They made a bit more show of it, and sort of made a dent you could feel, but hardly see. But still no penetration, and no serious damage of any kind.
Then we both tried our Cugir TTC (virtually identical to a Tokarev TT-33) pistols and shot 1970s surplus Romanian 86gr steel core ammunition. The RX8's brake disc proved tougher than the Tercel's. Frustrated by a lack of results, James unleashed a barrage of 7.62x25mm and ended up making a few cracks in the first surface. Some of the steel cores seemed to weld themselves onto the disc, which was unexpected, but made some cool marks.
We left Broke Disc Mountain satisfied and exhausted, sure to return in the future.