对当前研究弹丸膛内运动规律的两类模型（即假定弹带中心沿炮膛轴线运动模型和没有此假定的一般模型）进行了分析研究，以平衡弹丸为例进行了计算。认为假定弹带中心沿地膛轴线运动模型不能反映弹丸真实的膛内运动规律．在研究实际问题时，建议用后一种模型． Two types of models for studying the motion of projectile bores (that is, the assumption that the center of the belt is along the axis of the bore and the general model without this assumption) are studied and studied. The balanced projectile is taken as an example. It is considered that the assumption that the model of belt center motion along the borehole axis can not reflect the true motion law of the projectile. In the study of practical problems, it is advisable to use the latter model.