I would think twice before replacing the recoil pad! These red rubber "Jostam Anti Flinch" pads with the slant vents are quite "period" with the rifle, as they were availble well before WW2. They are quite often found on pre-war Mauser sporters. See f.i. Jon Speed's "Original Oberndorf Sporting Rifles", page 193. Afaik These recoil pads were offered by Mauser as a factory option. So it may be original to the rifle, other than the open sights.