Where is the bolt in relationship to the round in the magazine?
Is the bolt hitting the side of the round, or is it behind the round where it's supposed to be?
(If the bolt is behind the round pushing like it's supposed to be...)
Is it happening EVERY round, or every other round?
If the offending round is always on the same side of the mag, then you have a bent magazine lip.
(Remember, your mag alternates, left-right-left-right...)
Some magazines have the locking hole higher or lower than it's supposed to be, this will cause feed problems.
Some bullet shapes or nose types (soft point or open hollow points in particular) will give some rifles problems.
Heavier rounds have a different curve to the front of the bullet (Steeper Taper) and will cause problems in some rifles.
If your bolt is hitting the side of the round, you have a different problem...
I really don't want to get into that unless that's what's happening to yours.