Before you go loading the same brass to use in each rifle, fire a couple factory rounds through each gun and compare the headspace. If its the same or real close, I doubt you would have any safety issues loading one load for both rifles. However, if there is a .003"+ difference, I would keep the brass separate and size differently also. You will want to bump to bump the shoulder back approx .003", give or take a thousandth. I wouldn't do more than .005" or less than .002" with an auto loader.
Use a powder like Varget or IMR 4064 and work up, starting from around 40gr. You definitely don't want to run into high pressures, that just makes for problems with semi-autos.
As for brass, I use whatever I can but I prefer the thicker stuff for gas guns. I'd get a few hundred rounds of LC brass and start loading.
