I've heard LOTS of people say that if they could only have ONE type of powder for all of their loading, they would use Unique. Nearing the max, you can still load it in a .30-06 and push a 150gr bullet to about 2300-2400fps, getting ~.30-30 ballistics. I copied down the snapshot of a manual someone posted and it was saying 25gr under a 150gr bullet would give you 2400+fps at 60k PSI of pressure. OBVIOUSLY, START WELL BELOW THIS IF YOU ARE INTERESTED IN PUSHING ANYTHING WITH UNIQUE. Even though most people probably wouldn't be interested in trying to push Unique very far, I think being able to make loads like this that are still perfectly capable of taking Deer and such, but with half the powder and still significantly less recoil and muzzle blast, makes for a great alternative. I mean, toning it down a bit it is still easy to get 2000+fps at a relatively mild ~40k PSI, and it would still be effective at up to 200 yards on medium-sized game. But you'd be using half the powder ($$), have less recoil, and notably less muzzle blast. Out of my rifle, a 17gr load of Unique sounds about like a 9mm handgun, while even 40gr of H335 (a bit below the starting load) has significantly more "bang."
Also, FWIW, Unique has about twice the bulk of the H335 rifle powder I use in my .308. That is, my standard load has become 40gr of H335, and without adjusting my powder measure I get almost exactly 20gr of Unique per load. Both of those fill the case to a bit below the shoulder (shaking completed cartridges results in audible powder movement with either powder).
Rifle loading is slow enough for me that I can check every case so I'm not worried about double-charges. Plus since my "starting" Unique loads still fill a hair over half the case, a double-charge would be obvious. However, I can see where one could potentially have issues trying powder charges of about 13-14gr in the case, as a double-charge would be well over max (26-28gr) and would probably even be compressed under a bullet, but the case wouldn't overflow so a careless loader wouldn't have that obvious clue to stop him. Again, in general, I'd say start at a load that fills half the case (unless you are specifically looking to go slower and are willing to take the extra care to check each load), and you shouldn't have a problem. You could potentially even do this by adjusting your measure until two charges will just overflow the case. Half of that should be completely safe and still quite mild.
