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William, 22LR which is 22 Long Rifle only will work. WMR is Winchester Magnum Rimfire or 22 Magnum and will not work. Pictured difference here : https://gundigest.com/gear-ammo/ammunition/22-wmr-vs-22-lr-application-defines-this-rimfire-rumble

These Remington thunderbolt 22LR rounds will work fine in the M&P15-22

any 22lr ammo will work 22WMR is longer and fatter and will not work in the 15-22

William, I run these Remington Thunderbolt 22LR thru my M&P 15-22 with no issues. Do not use 22wmr, only use 22LR.