Comment on “A magnetic velocity Verlet method” [Am. J. Phys. 88, 1075 (2020)]

The implicit midpoint method described by Chambliss and Franklin [Am. J. Phys. 88, 1075 (2020)] is known not to exactly conserve energy for a spatially varying magnetic field, nor does it conserve angular momentum in a constant magnetic field. It is, therefore, not competitive with the widely used Boris solver in plasma physics, which conserves both.