Hi,
A "guard load" such as mentioned is new to me. But I have loaded a lot of "pop gun" loads for the '06 using cast bullets over Unique, and a few w/ Green Dot.
They usually run around 1200-1400 fps, and are reasonably accurate for 50-100 yd plinking and getting "trigger time" on paper. I shoot 'em in a bolt action: dunno if they'd cycle the Garand...
For the curious, the Lyman Cast Bullet book has a bunch, as does the out of print RCBS cast bullet manual if you can find it. If you can't, PM me and I'll see if I still have scans I can e-mail.
Rick C