Any rifle, whether its a blaser, a bolt action, break action action should not fire unless the action is fully closed. With any bolt only put handle half way down - it won’t fire.
In a Blaser if the bolt is not fully forward then the locking lugs are not fully engaged.
With a bolt completely in battery and then gun were to fire the bolt may be coming back pretty fast.
Some cartridges and ammo may well be close to the upper end of tolerances in terms of length and may exert a resistance to the bolt closing. I have noticed this with some factory ammo, and reloads when I haven’t fully resized the case - ie the shell holder is not firmly pressed at bottom of die.
It can also occur when chamber gets grubby with carbon build up at the lands.
A firm forward pressure on the bolt as you load usually solves problem in the field.