Hi R.C.
It's a non-cannister grade of powder, one that won't be commericailly available. There's also some specialty reloading techniques that go into these that result in a highly compressed powder charge. This came about from some experimental work at Lake City Army Ammunition Plant some years back, and if I recall, there was a bit of a ****ing contest between Hornady and LC over something related to the process. Looks like Hornady won, or at least LC got otherwise engaged. HAven't worked with any of the new Hornady stuff, but from what I'd seen of the earlier LC project work, I don't doubt their velocity claims.
Hoope this helps,
Kevin Thomas
Lapua USA