No, W-760 is not suited for a 308 gas gun. It is too slow for a rifle that does not have an adjustable gas block. It's a bit too slow even for a bolt gun, but it can be used.
This is true ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^. W-760 works great in 30/06, 270 Winchester and many other cartridges that use powders that are in the slower burning rates. W-760 is close to the burning speed of IMR 4350. I have used it in the 308 Winchester. You need a lot of powder, a long tube and it just doesn't get up to the speeds of other, better suited powders for the 308 Winchester.