Not arguing with Charlie. I owned 2 pairs of the Sordin/MSA and they are the crappiest NRR I've ever used. As far as sound QUALITY... they are very very very good. But even with the super comfy gel ear cups, they were just not good at attenuating the sound.
I would never recommend them for good NRR and the purpose you're asking for.
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I would recommend ALWAYS doubling up, though I've been happy with these:
SureFire EP3 Sonic Defenders will protect your hearing against Noise Induced Hearing Loss (NIHL) without compromising your ability to hear routine sounds or conversations in noisy environments. Their double-flanged-stem provides a Noise Reduction Rating (NRR) of 24 dB.
www.surefire.com
+ earmuffs (I normally use Peltors but am testing Razors vs Leights right now for a low cost option to see which is better-let me know if you want to get the results when I'm done)
for shooting pistol & silenced bolt guns; the surefire component barely drops the sound while using electronic ear pro, but when idiot lights one off by accident without ears on I'm somewhat safer- you can have conversations with just the surefire ones on
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I use foam earplugs + earmuffs when shooting anything braked or semis like ARs, or matches, or indoor, or on a. line
the concussion from brakes is real, rocks me head when I use a harsh brake
if you can run suppressed for bolt guns, definitely do so