If you use a Sierra Bullet use their data to start with.
Link to Sierra's data.....
http://www.rugerhunting.com/204_Ruger_sierra.pdf
I have gotten 1/4" 100Yard groups with:
AR-15, 204 Ruger 24" 12 twist DPMS fluted
R-10X
N-140
X-Terminator
IMR 4895
Winchester, R-P, Hornady all brass show well
205M is "the" primer for most all loads.
32, & 40 V-max very good.
39 Sierra also good with the best BC going.
Very easy to find loads with the 204 that worked, I started with R-10X and the rest came with time. I have a new favorite, it's X-Terminator for the 32-39-40 all small groups with a very clean burning powder.
never tried H-4895 but this link has some loads and about 12 using H-4895
http://www.204ruger.com/forum/viewto...=165&start=105