The energy accumulation and dissipation process in rock mass refers to the ability of rock to store and release energy during loading and unloading cycles. These properties are critical in geotechnical and mining engineering as they impact rock's response to cyclic loading and are crucial for evaluating the propensity of rock bursts. This study investigates the critical aspects of energy accumulation and dissipation within sandstone and coal-measure rocks having different grain sizes from the Sydney basin. The results indicate that as the grain size increases, the burst propensity reduces and thus the fine-grained sandstone imposes a relatively higher rockburst risk. In terms of dynamic failure time, the fine-grained sandstone shows a relatively lesser dynamic failure time, indicating a rapid release of energy and fracturing. The effect of grain size is also noticeable in Uniaxial Compressive Strength (UCS), elastic property and energy accumulation as well. Additionally, the study incorporates sonic velocity testing, examining both axial and radial measurements, to draw correlations between sonic velocity and compressive strength. The findings offer valuable insights into the complex relationship between the characteristics of coal measure rocks, their response to cyclic loading behavior, and their propensity of bursts.