Rem. RTL Premier hull, Rem. 209P primer, 15 #1 buck pellets, RP12 wad, and 25.0 grs. of SR4756
Or
Rem RTL hull, Win. 209 primer, 12 #1 buck pellets, 15 grs. of BP buffer, one 20 ga. BP .030" card over shot, and 24.0 grs. of 800X
Those are the first two loads I came across, but I have dozens of other options for #1 buck. Just be careful and use only published data. Don't try to construct your own data for something like buck shot loads. Some hulls, wads, and powders require different variables and or components. About the best advice I can offer is to just go buy a shotshell loading manual. One of my favorite books for this is "The complete Reloading Manual for the 12 guage Shotshell" published by Loadbooks USA, inc. . This is all unabridged information from powder manufactures. And the above data is straight out of that book, which was published in 2000.