Ok so I scored a MI quad rail for a great price on the EE. If I wanted to use the ms4 sling, I would need to buy the sling socket for the acs-l stock and then the rsa qd adapter to put on the rail?
http://www.aimsurplus.com/product.aspx?item=XMAG335&name=Magpul+ACS+QD+Swivel+Mount&groupid=1045
http://www.aimsurplus.com/product.aspx?item=XMAG337&name=Magpul+RSA+QD+Rail+Sling+Attachment&groupid=1045
Sorry for the dumb questions. I've never used qd before, only the paraclip/hk hook style slings.