If you are not a handloader and wish to shoot only factory ammo, then if the rifle has excessive headspace, you can likely
get away with some excessive headspace - if the rifle fires reliably.
If it is too bad, the gun might not fire all the time.

JDL notes the only way of correcting excessive headspace.

What makes you think the rifle has excessive headspace?]

If a rifle does have excessive headspace, like my Husky M46 9.3x57 with .019" headspace (.012" over standard SAAMI).

JDL notes the way of correcting the brass for that rifle.

This is what I did.
Note - 1st case is a brand new R-P 8m Mauser case.
The 2nd case is the 8mm Mauser necked up to 9.3 - note the neck length.
The 3rd case is an 8mm Mauser case necked straight.
The 4th case is the straight case necked for a crush fit, ZERO headspace in that rifle's chamber. Note neck length compared to the second case. THAT difference in .019".

The dies I use for necking ctgs. straight - in one pass- no failures.

Ctg. Lineup of Steps: #1 through #4