The brass disc and screw didn't hold anything else in place. That disc was marked with unit information pertaining to the rifle. The regimental details were stamped into the disc. During 1916, the stock disc was omitted, as having unit details on rifles gave the Germans information as to who was in the trenches opposite, and also it was realised that deleting the disc sped up production. Many buttstocks had been made but not yet fitted to rifles, and these sometimes had the hole for the disc plugged with wood.

Other rifles later had stock discs removed and plugged.

Cheers,
Matt