You can weigh the case, should be close to 900 grs. The S/T's weigh 833grs +/- a couple grains.
Whatever the difference is will give you an idea about how much powder they're using in their ammo.
I will post this again as a warning, one of the guys that myself and MrBen shoot with had loaded up some ST's. He was shooting them and I noticed that the muzzle brake was ringing on his AR-50. That and the muzzle blast was way more than usual. I asked him what he was shooting (that's how I found out they were ST's) and he said spotters. My next ? was what the powder charge was he was using and he replied 220grs of 5010!!! Me and MrBen took a few extra steps back after telling him that the MAX charge should be 190grs.
I will say that seeing an 833gr bullet shoot flat coming out of an AR-50 is pretty damn cool! Would I do it in my AR-50? Fuck no! Just hearing the muzzle brake ringing was enough to know that the limits were being pushed. And NO, I wouldn't suggest anyone on the board to try it either. That's why I posted it for anyone else that's planning on loading some up. Be safe, not stupid! That's a grenade next to your face that can and will fuck you up if you don't respect it!