[andy]

are same as lr (in construction). No they are not. The case has to be much stronger, thicker for the 2x greater pressures of the Mag Rimfire, and the Mag's bullet has a real JACKET, not just the copper wash of the .22lr bullet. a LOT of R and D and a lot more quality-contol HAS to go into rimfire mag ammo, because of the delicate balancing required, of a stiff enough case for containing the pressures, while keeping the rim soft enough to allow reliable ignition of the priming compound. Probably not NEARLY enough to really justify the 5-6x greater cost of the rimfire mag ammo, tho. I suspect that ALL .22lr ammo is foreign-made, and the low cost foreigners probably can't be TRUSTED to make adequately reliable .22 mag ammo.