If you can spend the money, you can get the custom molded in-ear earplugs with electronic inserts. I have a friend that wears hearing aids that uses them for shooting.
Looks like the cheapest ones are $900. https://earinc.com/product-category/hunting-shooting/
I have to say, I was skeptical of how bad they could be, and I saw a PW87 at the local shop, so I bought it. After about a dozen rounds, I polished it up and took it to the gun show, where I was overjoyed to have one of the usual guys outside the front door take it off my hands for about $50 less than I paid.
Best I recall, Johnny Ringo used a cartridge converted LeMat, unlike the real ones.
I just started watching the HBO Westworld series and saw that Ed Harris as "the man in black" uses one more like Johnny Ringo's with 9 cartridges and a shotgun shell.
Here's an article I found about it: http://www.wideopenspaces.com/hbos-westworlds-ed-harris-lemat-conversion-revolver/