Hey all,

This should be an easy question to answer for someone - 

Last fall I bought a Remington 7600 .243 for my son.  It only had one magazine, so I've been looking on and off for a second one.

I've seen some on EBay that have a button on the bottom left side.  What is that for/what does it do, and can I use a clip like that in the rifle?

Thanks!