Sorry, I don't know what the factory load is. That said, the 308 is definitely not a picky cartridge. I've loaded for a bunch of 308 rifles and from that experience I can say a healthy 308 rifle that cloverleaves with one powder will do it with two or three others as well.
Here's something to consider as you handload for this rifle: It is shooting very well with factory ammo, so pure neck sizing or partial FL sizing to a light "crush fit" may not be what the rifle will like best. So to limit the number of variables in your initial development, size the brass for smooth and easy chambering. (Not necessarily all the way down to like new dimensions though.)
If you can assemble straight cartridges I'd be surprised if IMR4895 doesn't have it punching them in tight with minimal development.
