The Concourse reports:
You’re the eldest son of one of the most reviled men in popular culture. You’re violently well-off, love guns, and have far too much free time on your hands. You, my friend, are Donald J. Trump Jr. And on the internet’s many hunting message boards, you have apparently found your home. Our boy isn’t just a casual forum haunt, though. Don Jr.—or someone doing a convincing and thorough impersonation of him—is a registered member of at least 25 different gun, bow, hunting, and fishing enthusiast forums.
There’s Speciality Pistols, Brian Enos’s Forums, and Tradgang; Accurate Shooter, go2gbo, Stickbow, Tradtalk, and Archery Talk; Greybeard Outdoors, Long Range Hunting, The Fly Fishing Forum, Handgun Hunter, CastBoolits.Gunloads.com, Sniper’s Hide, and 24hourcampfire; Trout Predator—Trout Predator!—and Predator Masters Forums; Saddle Hunter, TradRag, Saubier, and Crossbow Nation; 1911Forum.com, Shotgun World, The High Road, and Benchrest Central. This list is almost certainly incomplete.
Hit the links for much more including screencaps of his posts to the forums.