Sometime last winter or early spring I was digging around on one of the outdoors websites (I think it was OL, but I'm not 100% certain) and came across a very short review for a rimfire AR type rifle. Supposedly it would fire .22, .22 mag, and .22lr interchangeably, even from the same magazine. Also, supposedly, it was made by M&P. I've checked OL, I've checked the M&P/S&W sites, and I've Googled until my eyes hurt, but I can't find mention of it anywhere.

Anyone know anything about this? Did I dream it? Did the manufacturer plan to do it and then back out? What gives?

And while we're at it, any tips for a decent AR-type rimfire that won't break the bank but that has pretty good accuracy at about 75-100 yards?