When performing a similar type of impact simulation, consider the following recommendations for obtaining better accuracy and faster performance:
Activate impact constraints (KEYOPT(7) = 4 on the CONTA174 element) to enforce energy conservation at the contact interface. This option helps to maintain accuracy of the nonlinear transient response over long simulation times.
For rigid- or elastic-impact scenarios, use the HHT time-integration method with small numerical damping (0.1) to damp out high-frequency noise.