XM-248 LMG Manual

Rather than explain the background of the XM-248, I will put you in the very capable hands of Weaponsman.com, who has posted an excellent 3-part series on the development leading up to the XM-248, entitled The SAWs that never WAS:

Part 1, Intro, and XM106

Part 2, the XM-248’s Forerunner, XM235

Part 3, the XM248

What I have to add to that information is a copy of the 1979 Ford technical manual on the gun:

XM248 Technical Manual (English, 1979)
XM248 Technical Manual (English, 1979)