The 30WSSM or 30OSSM performance is closer to a 308. The advantage it has over the 308 is that it is held to a slightly higher pressure rating yielding higher velocities. While that kind of performance is impressive out of an AR15 sized automatic, your options are limited to hand loading with that caliber, thus eliminating any advantage you would have over a hand loaded 308. The other disadvantage is that due to the short magazine length of the AR15 you are stuck loading 150gr bullets or lighter unless you purchase a separate UMAR lower from Olympic arms. I use a UMAR for loading and long range shooting the 243WSSM with 105gr+ bullets. My one example is of fine quality.
From a practical standpoint, as of today, the 25WSSM is at the upper limits of the AR15 platforms capability without having to switch to a specialized lower. I don't want to dissuade you from a 30WSSM if that is what you want, I just want you to realize that your not going to be able to load 160gr bullets at 30-06 velocities and run them through a standard lower receiver.
