“The HAC-7 was a rifle designed in the 1980s, and only available for a short time before the Holloway Arms Company went out of business. It was designed as a military-style weapon, although what military contracts it may have hoped for I don’t know. The design concept was quite good, utilizing elements form the AR, AK, and FAL rifles (mostly the AK). It was chambered for the 7.62mm NATO cartridge, using aluminum waffle-stamped AR10 magazines modified with a notch in the spine for the HAC-7’s AK-style magazine catch.
“Originally, plans were to offer the HAC-7 in a variety of configurations: left and right handed ejection, normal, carbine, and sniper barrels, full-auto versions, etc. The financial failure of the company prevented this from happening, though.
“In total, approximately 300 guns were made, including about 30 left-handed carbines, about 20 left-handed rifles, and a single sniper model. Twelve were set aside for manufacture as full-autos, but they were later assembled and sold as standard semi-auto versions instead. All the guns were equipped with side-folding stocks.”
This is an interesting design that could be pretty easily revived. There are plenty of people who want non-AR- or AK-based semi-automatic rifles and it has a slick design that looks like it really puts accuracy at the front of the design while maintaining a gas piston system.
There is one company that makes a similar AR-15 upper receiver, Adcor.