For a post WW1 rifle, the plate would be horn or plastic with the "MAUSER" logo on it unless a metal one was specified.
Pre WW1 sporters usually had one made of horn with a stylized WFM logo.
Some had horn or plastic with simple horizontal lines cut in the middle section.
Metal plates could be ordered with a trap, some had the MAUSER logo and some had the horizontal cuts.

If your desire is to replicate a Mauser factory sporter, the plastic one you have should be fine.