We consider a pencil-shaped active medium consisting of two- level initially excited atoms and described by 1D Maxwell- Bloch equations. With the help of these equations solution without slowly varying envelope approximation we shown, that internal field reflections from the ends of the sample transform the so-called 'lethargic' regime of super-radiance (SR) pulse amplification to the amplification regime similar to usual exponential law. iT can lead to the pulse development acceleration and counter-propagating waves synchronization. A simple formula for SR pulse delay time evaluation is presented. The criterion of the counter- propagating waves synchronization is discussed.