BulletDrop
Gushroom
Bulletstop - fps logic puzzles
Hot dogs
Hornady
Chairgun Elite Ballistic Tool
JetLab, LLC
Arken Ballistics
Pango Optics
Lapua Ballistics
RightSpot Ltd
GeoBallistics
Sheltered Wings, Inc.
Hornady Reloading Guide
Applied Ballistics
Range Buddy
Atriarch Targets