Is there a way to remove regular 5.56 bullets from raid block, but not explosive rounds?

Yes, remove the "bullet" item from Raid > damageTypes.  The bullet damage will be ignored, but explosive rounds (I think) also have explosion damage which would be counted.

I remove the "bullet" from raid-> damage types. But still activates the raid block any idea?

Make sure you reload the plugin after making configuration changes.

its fixed thanks