No idea, but I think the magnums were recalled. Probably has some additional collector value and might be worth your while to sell it rather than risk damaging it by shooting it.
Good luck.
They stopped making them for a few reasons:
1. Low sales
2. Platform was known for breaking when used with 22WMR ammo
3. Reliability issues
4. More expensive to manufacture
5. And most importantly: They feared guys were going to rebarrel them to 17HMR. The gas system is not right on the 10/22 to support that cartridge: The 17HMR requires a "delayed blow back system to operate safely", so some were having catastrophic failures. They know a lot of guys are too stupid to heed the warning, about doing this, so they discontinued the magnum altogether, to minimize potential lawsuits.