30 is about the max you will find in ear muffs. You may find slightly better but not much. You may want to consider using both in ear hearing protection (ear plugs) and over ear (muff type) at the same time. It will give you much better noise reduction. That is what is used in industries with high noise exposure (Jet engines).
If you use in ear hearing protection you have 2 options one use type or multi use. In one use type use them once and throw them away reusing them after they have been smashed and fit in your ear the protection can be reduced. Also they are contaminated and can increase ear infection. If you use multi use in ear hearing protection remember that putting in ear plug increase the contaminants in your ear by 700%. Ensure you clean them thoroughly between uses. Wiping them on your pants is not considered cleaning them.
If you determine you need hearing protection wear it at all times you are exposed to the noise. The over all NRR is reduced each time you take them off (With a nrr of 30 if you wear them 100% of the time you are exposed the NRR is 30, if you wear them 99% of the time the protection drops to 20. If you wear them 50% of the time your rating drops to 3.
If you can't carry on a normal conversation the noise is to loud and hearing protection is required.
