When I remove frame rivets I use a 3/16" Short-Length Cobalt Steel Drill Bit part number 2416A19 from McMaster Carr and drill down about 3/8" into the head then use an air hammer with a flat chisel to blow the heads off. With the 3/16" hole in the center the rivet head comes off with just a few blows and it relives just enough stress in the body of the rivet that I can usually tap it out with a drift punch without much effort.
If it's hard to get leverage I will predrill with an 1/8" then come back with the 3/16" the save some time, I'll order new drill bits every time before I'll tackle frame rivets to save on the fustration of drilling with dull drill bits for hours wishing I had new drills.
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