I'd prefer more, especially for indoor range work. Use foam ear plugs + the muffs if you do any of that, and if outdoors and using only muffs immediately stop and put on foam plugs if it's uncomfortably loud or you notice any ringing at all.
Mine are only rated for a reduction of 20 db and they work fine, especially for 9mm. I rarely shoot at indoor ranges but when I do I wear foam plugs under the muffs.