Wyoming appeals ruling vs. BATF
Essentially, Wyoming treats DV convictions as do many states. A person can later apply to have the conviction "expunged." If the court grants it ... well, lotsa times in the law the law does one thing and the reality is another. The court issues a ruling saying the conviction is set aside and expunged. But the conviction in the files isn't torn up, nor sealed. And if the person is charged a second time, it can be cited to prove this is a second offense. This arrangement, BTW, is quite common.
GCA 68, as modified by the 86 amendments in FOPA, says a conviction doesn't count if it has been expunged or set aside. ATF's position is that the statute and its history doesn't define "expunged," and if a conviction is still on file and has legal effect, then it ain't expunged. Wyoming position is that the purpose of FOPA is to make state law govern a state conviction (as it did not prior to 1986) and the statute, and the court orders, say "expunged."
For my money (and I actually had a role in drafting that part of FOPA, not a big role, Jim Featherstone did most of it but he's dead and can't be asked) -- the parties ought to research the history of expungement as it existed while the statute was being debated (1979 or 1980 to 1986). As I recollect, the first big expungement proceeding at that period was the Federal Youth Corrections Act (sort of like federal juvenile court, but extending up to age 25, I think). Some national body had recommended that states adopt similar provisions, and they were starting to do so at this time. So, to my mind, if the state statutes of that period paralleled those of Wyoming, then that's the background in which Congress acted, in which expungement either did or did not mean completely wiping out the record and nullifying all legal effects. I haven't done the research and don't know what the answer would be.