Drop-in anchor

A drop-in anchor system comprising:

• a drop-in anchor including:
• a tubular sleeve having a first end and an expandable second end, the sleeve tapering in inner diameter from the first end to the second end at a sleeve taper angle;
• and
• a plug insertable in the sleeve, the plug is configured and disposed to expand the expandable second end of the tubular sleeve when driven into an installed position, the plug tapering at a plug taper angle along substantially an entire length from a head end to a tip end, wherein a difference between the sleeve taper angle and the plug taper angle is about one degree or more, and wherein the sleeve taper angle is greater than the plug taper angle;
• and
• an installation tool configured to form a hole in a workpiece into which the drop-in anchor is insertable and to drive the plug into the installed position in the sleeve.