My first thought was it probably had a metal shotgun style plate like the SRC's, but a metal buttplate wouldn't be too likely to have been replaced with the buttstock being in good condition. So a HRB for the fun of it.

“The Savage 99 Pocket Reference”.
All models and variations of 1895’s, 1899’s and 99’s covered.
Also dates, checkering, engraving.. Find at www.savagelevers.com