Youtube Vids:

• School of the American Rifle

• Small Arms Solutions

• Midway & Brownells for assembly guides

The only gun-specific tool that you absolutely need to have is an armorer's/castle-nut wrench.

Learning the entire cycle of operations, i.e. exactly how the gas system works in relation to the BCG, ect. will help you diagnose any specific issues and may guide your part choices.

The most important thing for accuracy is the barrel, but even cheap rack-grade stuff is serviceable if free-floated, about 2-3" moa from a $89 BCA is the worst I've seen from an AR. Unacceptable imo, but if its a red-dot close range gun? up to you.

I don't actually own an armorer's guide, but having one may be worthwhile if you want to learn quickly. AR's are basically legos, especially if you aren't doing a barrel/gas block install. The BA Hanson barrels are probably to easiest to build an upper with imo, since they come with a gas black pre-dimpled and pinned. If you're just assembling a lower, you just need to follow a video and it'll be hard to screw anything up beyond loosing springs and detents. Try assembling inside a clear freezer bag if you don't have spares!

• Barrel: I'd go Nitrited>Chrome>Stainless until you get up to the $250 range, where I'd go for a chrome-lined Criterion.

• Bolt Carrier Group: Most important part of the rifle. Nitrided is my favorite finish due to how easy it is to clean. My first rifle has a Toolcraft nitrided 9310 bolt in it, which I now avoid in favor of C158 bolts. Nitriding is surface hardening process, and 9310 is already challenging to temper correctly to avoid being too brittle. Nearly all failed AR bolts are nitrided 9310. Phosphate isn't much harder to clean, and may be all that is available right now anyway. One common source of malfunctions are bad extractor springs- replacing the springs/o-rings/inserts with a BCM/Springco/Colt kit is never a bad thing. Extractors are a wear item if you manage to shoot several thousand rounds.

• Trigger: The best deal in triggers is the Larue MBT-2s. It's all I can justify beyond a decent mil-spec trigger. Giessle G2S is worse imo, and my SSA just 'feels' different and isn't better in any way.

• Optics: I'm a big fan of rifle-length iron sights. If you're building a 16" mid-length I prefer a red dot or LPVO. Primary Arms is my preferred value LPVO/prism scopes, the Holosun's dot-in-circle are a bit sharper for my astigmatism. Aero Precision makes the lightest/cheapest mounts, but you really need an Arisaka-style scope leveler to install, since scopes tend to rotate in the rings as you tighten down.

• Muzzle Device: I'd start with an A2. By far the best value, and a break isn't worth the blast/flash aside from competition.