Take this from a guy who deals with industrial hygiene stuff for a living:
1. 24db NRR is shitty for a pair of earplugs. You can find $.10 ones that have over 30db.
2. 24db is the absolute MAX in lab testing assuming 100% fit. You'll most likely get something around 8-10db depending on if you know how to insert and wear them properly.
3. When you firearm is pumping out 120-130db every shot...you need something more IMHO. You don't need to "hear" the gunshot and have ringing in your ears to damage your hearing.
If you want those though...go for it. To each their own. My advice would be to get a good pair of ear muffs to go with them. It's very strange, to me at least, that people are willing to shell out big bucks for firearms yet they cheap out when it comes to their own personal safety. Thousands of guns, tens of thousands of rounds...ONE pair of ears. Once they are gone, they are gone. Never understood it myself.