I'm talking T-posts, about 22" deep x 1-5/8" diameter x 24". I use a horrible freight SDS MAX (NOTthe regular sds) hammer drill and a little bitty 3.5 horse B&S 2KW genset with handle/tires, about like dragging a push mower. Little pancake compressor and a long wand blower gets the dust out of the hole if it really needs it, usually not I just hammer the post down into the powder to the depth I want and move to the next one. Key is a cruciform-tip carbide masonry bit, 24" drilling length, about $200. Two-insert tips are no good for hard rock, but the cruciform point of good quality will easily drill granite, it's a single-jack on steroids. Takes me under two minutes to sink 22" in hard crystalline limestone. For the T-posts I'm concreting in place, I have a 2" x 24" bit and that loads up the drill pretty good, it gets hot and I keep an ice chest and trash bag handy for long runs, but it does fine.