I've used muzzle devices to tune rimfire rifles, but not centerfire.
On 22lr barrels, I don't use a crush washer. I use an O-ring or a hose gasket. The hose gasket is thicker and may permit a larger range of adjustment, but O-rings probably provide as much range as I've ever needed.
The most pronounced result was from the heaviest device, an eight ounce krinkov device that functions as a dwell time booster on centerfire rifles. Adjustments don't have the same kind of repeatable precision that a click adjustable or marked barrel tuner, so I typically first adjust it with my torque calibrated hand, then have to test it to see if it's dialed in.
If it isn't dialed in correctly, the result is a real mess, much worse than a barrel with no weight. If it starts throwing crazy fliers, I'll check it and find that it has loosened.
For me, the better, more care-free option is a thread protector held on with an O-ring. This also had the benefit of allowing easy cleaning of the muzzle and crown.
It isn't a flash hider, but I've also used heavy rubber doughnuts forced into the barrel.
https://www.ebay.com/itm/254509869537 These are so tight they stay put, but don't require a precise fit to the barrel the way a metal collar will so you can place them at different points along a contoured barrel.