As with all things, the records for the Interarms/Ranger pistols were recorded on tape and routinely passed along to the BATF crew. If the BATF folks saved them, then the records would be available today -- if, in fact, someone were inclined to file an FOI request to get them out of hibernation. The cost would be considerable, no doubt, seeing as how the government would require a copying charge, and a lot of copies would be necessary to cover the serial numbers of all of the guns made.
What's really needed is for someone living close by to get inside and examine the records and get a month-by-month assessment of the pistols that were made during the term of the Ranger/Interarms contract. Even that wouldn't be a sure bet, however. Consider, for instance, the gun that was assembled, sent to Interarms, inspected and returned as wanting, only to be reworked and refitted, or perhaps even retrofitted, and then revamped and sent back for additional inspection and perhaps even eventual acceptance. But ... it would be far better than what we have now, which is nothing but the test targets, and those are only good when they were recorded with full dates: a month as well as a year. Too often, that, too, wasn't the case.