Several old German mounting system, for instance by Schüler, used the idea to use form-fitting dovetails combined with a push-button or lever to lock it against lengthwise movement. This idea was discarded long ago, because any such merely form-fit without a clamping effect will develop "play" when sujected to frequent recoil or after some detaching/reattaching. FI such a system was used in WW2 on sniper 98Ks with the "Kurze Seitenmontage". In the course of time an rather ungainly clamping screw was added to these mounts still in sevice to take up the developing looseness. For new sniper rifles it was soon replaced by other mounting systems. I would deeply mistrust such a mount on a heavy recoilig rifle, no matter how well made!