3/8" and 1/2" steel gongs
Made it out to 500yds on the 10"x12" gongs today. I hung three of them off a swing set at the range, one is 1/2" and two are 3/8". The 3/8" gongs worked good at 500yds with the 308win just leaving slight dimples. At 500yds the 416wby and 400gr XLC's were still doing some damage to the 1/2" so 600yds will be a minimum I'm guessing for them. The white paint works great too Ian, thanks for the tip there too. The guy at the steel yard said the 1/2" remnant was pretty soft stuff, I think it's softer than the 3/8" stuff just buy the surface scarrs they leave. I'll see if he has some harder stuff next week.
I welded nuts on the back in the upper corners to fasten wire to hang them from so they tilt a little tward the ground too. Hanging from 18" or so of wire they move for a few after being hit and are easy to see hits on the white also.