Barrel tuners are used on .22 benchrest guns more than anything else, there are several brands of them out there.
Since one cannot reload .22lr and there are only a few brands of match ammunition, which are not always available, a barrel tuner is the most practical and effective thing one can use to match up barrel and load for the best accuracy.
An alternative to barrel tuners which no manufacturer has offered yet would be a series of match loads with slightly different loads in specific increments. For this to work well, five or ten different loadings of the same case and bullet would have to be manufactured. - Unlikely to happen at best.
An old trick was to take a bit off of the length of the barrel, test for accuracy with a chosen loading, then take a bit more off to see if accuracy improves. The problem with this of course is that sooner or later you will pass the "sweet spot" and the next bit of barrel length removed will worsen, not improve accuracy.
Since nobody has come up with an easier, quicker and more effective way to match load and barrel, the tuners are very popular among rimfire benchresters.
One thing I noted while looking at the different brands is that they seem kinda pricey to me. It's just a movable weight on the end of the barrel, when it comes down to it. - I do not see any particular reason that they have to be pricey, but the same thing can be said about adjustable shooting rests, which also trend to being overly complicated and expensive, for what they do.
I guess that's part of the fun, fooling around with complicated, nicely machined gadgets, etc..