The use of a guide tube technique to inject pellets in pellet-plasma experiments is described. The effect of the guide tube on the mass and speed of a slowly moving pellet ( nu approximately 150 m s-1) is negligible. To improve the divergence in trajectories of the pellets on leaving the guide tube a specially formed brass slide has been developed, which improves the aiming accuracy by a factor of 10. A simple method for determining the mass of larger pellets by means of a plate capacitor through which the pellets are shot is described. A method for small pellets as well has been investigated. This scheme employs a microwave cavity operating at aroung 9 GHz.