My Century L1A1 was built on a Hesse receiver and has always worked fine. It was a good deal when I bought it and have no complaints. Hesse got a bad reputation from builders and his piss poor customer service. But if the gun works they usually work as well as any other.
Hesse originally built guns with Imbel receivers (FAL files used to have an article from American survival guide that gave them a good write up). They later manufacturered their own receivers and usually they needed more work than an Imbel or DSA to assemble. Century built guns with them. Usually the Century guns that had problems were related to their two piece gas piston bending, the gas plug being installed on the grenade setting or the cross pin missing from the gas tube and not receiver problems.
If the gun works and the price is right this may not be a bad deal.