I would check alignment with a boresighter, just to establish a reference point. Then fire a half dozen shots fairly quickly and then check with the boresighter again while the barrel is hot, just to see if things shifted. Then check again after barrel has thoroughly cooled to see if it settled back to the original reference point.
Wouldn't be the first military Mauser barrel I saw that walked around as it heated up. I had a 7x57 Mauser that did pretty much what yours is doing. A fresh barrel cured that rifle's ills. (unless I inadvertently corrected some other issue in the process.)
Last edited by gnoahhh; 09/19/17.
