Ammo where you are???

went into bass pro shop last week end and found .22lr ,limited to 3 boxes of 50. for only 2.75 a box and plenty of other ammo . first time in md. for 3 years! (federal thunder) 1225fps. got home then read a review that said dont use in smith & Wesson mp15-22 jams up . guess what kind of gun I have? the last brick I got off the internet was $110 I was told buy a le that the gov ordered 100,000 mp type rifles for training only and they use .22lr ammo because it is cheaper and better for training.