Here are the details of the Infanterie-Lehr-Regiment tests, that I have translated from the original:
“In 1918, the German Lehr Infantry Regiment conducted live-firing tests with T-Gewehrs. A British heavy tank was used as the target. On 25.9.1918, Army Group Crown Prince presented a report of the results to OHL:
1) All 4 shots at the fuel tank, which struck at an angle of around 60°, richocheted away. The tank would have remained battleworthy.
2) Four rounds were fired at the door, observations slits and MG port in the sponson from a range of 300 m, impacting at an angle of 45°. One round penetrated and the rest richocheted away. The tank would have been capable of moving and fighting.
3) Four shots were fired as described in 2) but impacted at an angle of about 90° from a range of 200 m; one shot penetrated, one bounced off, and two missed. The tank would have remained battleworthy and would have only become incapacitated by severe damage to the engine.
4) All 3 shots fired from 100 m penetrated the targets described in 2). A tank crewman operating the machine gun or main gun would have been injured or killed and the engine damaged. The tank could possibly have been incapacitated.
5) Three shots fired at observation slits and gun ports from an angle of about 75° and a range of 100m resulted in one round passing through the open gun port, a ricochet and a miss. The first shot would have knocked out the machine gun, injured or killed the gunner, or damaged the engine. The tank would eventually have become immobile.”