Introduction

Which modern anti-aircraft guns would be powerful enough to penetrate the armor of a World War II (WWII) tank? This seemingly simple question reveals a complex interplay between defensive technology and offensive capabilities. The answer can vary widely depending on the specific year and theater of WWII, as well as the types of anti-aircraft guns and ammunition available.

Early War Years: The .30 Caliber's Unlikely Success

At the very start of WWII, a lowly AN/TWQ-1 Avenger, equipped with a .50-caliber M3P machine gun and an M2 Browning derivative, could surprisingly make a formidable platform for hunting light tanks and tankettes. The Avenger's advanced forward-looking infrared (FLIR) imager provided unparalleled spotting capabilities, allowing it to effectively target many of the interwar tanks and tankettes in service among European powers and Japan. Even in the Pacific theater, the Avenger could remain effective throughout the war against the Type 95 light tanks and Type 97 medium tanks, especially if it used armor-piercing ammunition.

Advancements in Armor-Piercing Ammunition

M2 and M8 armor-piercing incendiary (AP-HEI) ammunition of the period would work reasonably well, but modern saboted light armor penetrator (SLAP) ammunition would significantly increase the Avenger's effectiveness. With a rate of fire of 1000 rounds per minute, the M3P could likely penetrate the armor of Japanese tanks out to 700 meters. While complete penetration from every angle may not always be achieved, the continuous barrage of rounds would eventually result in casualties by puncturing the engine and blocking gun turrets.

Mid-War and Late-War Years: The Decline of Light Machine Guns and Older Guns

As the war progressed, the effectiveness of light machine guns and older anti-aircraft guns in penetrating tank armor diminished. In the European theater, or against Allied tanks, even with FLIR optics, machine gun-based systems like the Avenger would struggle to perform effective penetrations. Sniping tank commanders remained a viable tactic, but it was not the same as penetrating armor.

Similarly, 20mm to 30mm platforms also struggled to achieve significant penetration by the mid-war period. High explosive (HE) ammunition would damage the exterior of tanks and devastate their guns and optics, but probably wouldn't breach the actual armor even with sustained fire.

For example, the 20mm Phalanx CIWS, firing armor-piercing ammunition at 4500 rounds per minute, could erode mid-war and late-war tanks to the point of penetration over several seconds. However, individual rounds are unlikely to achieve complete penetration against most late-war tanks. Thus, these anti-aircraft platforms fall into a category of "killed the tank crew, killed the tank, definitely penetrated the tank, probably didn't kill the tank through penetration."

Naval Anti-Aircraft Guns: The 40mm and 57mm Bofors

Traversing into naval anti-aircraft guns, 40mm L/70 and 57mm L/70 Bofors guns are particularly interesting. These guns use 3P (three-part) ammunition that includes programmable armor-piercing functions. This ammunition can work incredibly well at penetrating the armor of early war tanks and killing everyone inside. It has a decent chance of achieving the same against later tanks.

The Bofors' powerful 3P ammunition is designed to maximize the impact on armored targets, making it a potent weapon against both air and land targets. The combination of high muzzle velocity and a penetrable warhead ensures that it can breach the armor of tanks, especially when fired in a concentrated barrage.

Moreover, the 57mm Bofors with its higher calibre and more powerful ammunition can achieve even greater penetration. Its 3P rounds are specifically designed to hunt down tanks and other armored vehicles, making it a valuable addition to any anti-tank arsenal.

Conclusion

The effectiveness of modern anti-aircraft guns in penetrating WWII tank armor is a testament to the rapid advancements in military technology over the course of the war. From light machine guns to powerful naval guns, each development has brought new levels of capability. However, it is clear that modern anti-aircraft guns have a significant capacity to penetrate tank armor, making them a valuable asset in any combat situation.