Let's see if I understand the government's argument in the O'Brien case decided today...
If the government wants to lock someone up for 5 years for using a gun during a crime, they have to prove
the guy used a gun beyond a reasonable doubt. But if they want to lock up someone for 30 YEARS(!) for
using a machine gun and don't have strong enought evidence to prove it at trial, they only need to convince a judge at sentencing that the fellow used a machine gun "by a preponderance" of evidence (a much lower standard than "beyond a reasonable doubt.")
Because the prosecutors' attempted end-around the jury was so contemptible, the Court's 9-0 rejection of it is well-deserved. Sentencing junkies can find the Court's full opinion here.