Building panel with a mechanical locking system

Building panels provided with a mechanical locking system comprising a tongue, at an edge of a first panel, cooperating with a tongue groove, at an edge of an adjacent second panel, for vertical locking of the building panels wherein

• the tongue comprises a resilient and displaceable tongue part,
• the edge of the first panel is provided with a displacement groove to obtain the resilient and displaceable tongue part, said displacement groove is downwardly open, and comprises an inner wall, an outer wall and a planar upper wall,
• the tongue is formed out of the edge of the first panel,
• the resilient and displaceable tongue part is configured to be displaced into the displacement groove by a lower lip of the tongue groove during assembling of the first and the second panel by a vertical displacement of the second panel toward the first panel,
• the outer wall of the displacement groove at a first and upper part of the displacement groove, at the upper surface of the tongue, comprises a sidewardly-facing cut, such that, in a stress-free state before the resilient and displaceable tongue part is displaced into the displacement groove, the resilient and displaceable tongue part is entirely located vertically lower than the planar upper wall of the displacement groove, and
• the outer wall of the displacement groove at a second part of the displacement groove, below the resilient and displaceable part of the tongue, is sidewardly open.