Contour of the bottom of the magazine is different to match the different intended applications. May or may not be easy to remove a JX-1 from a 10/22 given the reduced area for gripping.
Thanks all. A friend gave me a NIB BX-1 and I wanted to know if it worked well in my 77/22 before I took it out of the bubble pack. It's out now and works fine.
The date on the back of the package is 1/88, price $9.50.