AR-15 build draft

_drafts/ar-15-build.md

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+---
+layout: post
+title: AR-15 Build
+description: I wanted to (and inevitably did) build an AR-15.
+categories: [Projects, Firearms]
+tags: [firearms]
+---
+
+Last year, my brother bought an AR-15, so of course I wanted to get my own after I shot it. As a first AR-15, I was leaning heavily towards buying a complete rifle, but some research pushed me towards building one. The internet is full of "build vs buy" dicussions so I won't hit that too much here, but the ability to customize the look and features while also (potentially) saving a little money is what decided it for me.
+
+## Build Motivations
+
+These were my motivations for the build. They aren't hard requirements or goals, but they did drive my decisions when selecting parts.
+
+- Accessibility: Simple enough for a first-time builder.
+- Versatility: Able to do most things fairly well.
+- Aesthetics: More modern looks compared to the classic M4/M16 design.
+- Cost: Near the cost of a comparable off-the-shelf design.
+
+To elaborate a bit, I wanted a gun that would be simple enough for a first build, but not so minimal that I would want to build something fancier right away. It should be versatile enough to cover short-medium range shooting and possibly light varmint hunting. Finally, it should have good value for the cost, with a price near similar OEM options.
+
+### Build Vision
+
+Based on my motivations, and some inspiration from browsing other builds on the internet, I settled on this list of features.
+
+- 16-18 inch barrel
+- Floating handguard
+- Adjustable stock
+- Low-power optic
+- $1000 budget
+
+## AR-15 Configuration
+
+Even within my list of features, there were still some decisions to be made about the final build. I'll cover a bit of what I learned from my research about a few of the configuration options there are. The usual "I am not an expert, please don't quote me, trust but verify" warnings apply.
+
+### Barrel Length, Style, and Material
+
+The barrel is probably the most impactful part of an AR-15 in regards to accuracy, and there are many options available in pursuit of different goals.
+
+Generally, longer barrels give more velocity and (arguably) better performance for long-range shooting, while shorter barrels are lighter and improve "dynamic handling characteristics", i.e. they are easier to move around quickly. I stuck with 16 inches as I wanted a shorter build with less focus on long-range target shooting.
+
+The material mattered less to me, but there are many options on the market. Some barrels have bores with chrome lining, there are different options for coatings, different manufacturing methods, and the list goes on. There are many other resources online that cover this better than I can even if I cared to try, so I won't.
+
+There are also different barrel profiles, which are best thought of as what the barrel looks like from the side. Pencil profiles are thinner than mil-spec to reduce weight but get heat up faster and aren't as stiff, reducing accuracy. Government, M4, and A2 [verify] profiles are closer to mil-spec, attempting to balance weight and accuracy. Heavy profiles are thicker than mil-spec, compromising weight for accuracy and heat capacity.
+
+Then, there are different gas system lengths, which defines where on the barrel the gas port is drilled to direct gas to the upper receiver. Pistol-length is only used for very short barrels, like in pistols (Wow, how insightful!). Carbine-length seems to be the default. Mid-length is a bit longer and seems to be increasing in popularity. Rifle-length is even longer and is generally found on longer barrels.
+
+Longer length gas systems are intended to soften felt recoil by reducing the pressure of the gas that cycles bolt carrier group (BCG). Some argue this reduces reliability if the gun is very dirty.
+
+The gas system length along with the barrel length determine the dwell time, the amount of time between the bullet passing the gas port and exiting the barrel. AR-15s need enough dwell time to fully cycle the action. Determining this with hard numbers is, well, hard to do, so most people seem to recommend following a known-working configurations to prevent issues. The further you deviate from the "standard" configuration (16 inch barrel, carbine-length gas system, carbine buffer weight), there's more opportunities for problems.
+
+### Buffer Length and Type
+
+There are two types of AR-15 buffers and buffer tubes, and two length options within these types. First, there are both commercial and military (mil-spec) types, which are are incompatible with each other. The most common appears to be mil-spec whether or not it is actually better than commercial.
+
+The second choice is easier, carbine or rifle length. Adjustable stocks require carbine length, so I went with that.
+
+### Buffer Weight
+
+There are different weights available for the buffer, ranging from carbine (the lightest and the default for most people), H1, H2, and H3 (the heaviest). The correct weight is related to the barrel length, gas system length, if you have a suppressor attached, gas port hole size, what ammunition you use, desired reliability when very dirty, desired recoil characteristics, the position of the moon, and if you ate a healthy breakfast.
+
+Generally, start with the carbine weight and increase as desired while evaluating reliability and ejection patterns. I ended up with an H1 buffer weight, which has been very reliable with my 16 inch barrel and mid-length gas system.
+
+### Optic
+
+The optic chosen is based on the intended use case of the rifle. My oversimplified understanding is red dots for close range, low-power and variable magnification for moderate ranges, and high-power scopes for longer ranges and hunting.
+
+## My Build
+
+### Lower Receiver
+
+| Brand          | Price  | Source             |
+| :------------- | :----- | :----------------- |
+| Aero Precision |  | Fleet Farm (local) |
+
+The lower receiver is the what the US goverment considers the actual firearm part. I didn't want deal with buying online and shipping to an FFL, so I was a bit limited by what I could source locally. Fleet Farm stocked a few options, this Aero Precision part and another cheaper brand. The Aero had some more features, including the threaded bolt catch pin, so I went with it.
+
+### Lower Parts Kit
+
+| Brand          | Price  | Source             |
+| :------------- | :----- | :----------------- |
+| CMMG |  |  |
+
+A generic parts kit. It included a grip which I didn't need, but I had a hard time finding parts kits in stock that included a mil-spec trigger and didn't include a grip. Some kits omit the trigger and or include a subjectively better trigger, but I wanted to stick with mil-spec here.
+
+### Buffer Kit
+
+| Brand          | Price  | Source             |
+| :------------- | :----- | :----------------- |
+| Aero Precision |  |  |
+
+This included the buffer tube, spring, and buffer weight. They can all be source individually, but the compelte kit saves a bit of money. The enhanced [verify] version makes some tweaks on the mil-spec design that I though were good. Also, the standard version wasn't in stock and other kits were more expensive at the time.
+
+### Upper Assembly
+
+| Brand          | Price  | Source             |
+| :------------- | :----- | :----------------- |
+| Aero Precesion |  |  |
+
+I went with an complete upper to ease assembly difficulty. In hindsight, I probably would have been fine assembling the upper myself, but this kit was on sale with a BCG and charging handled included, which saved quite a bit of money compared to sourcing all the part individually.
+
+This upper had a 16 inch barrel, which is the shortest legal length while still being a rifle and not a short barreled rifle (SBR). I liked the look of the floating handguard, and it had picitanny rail on top and M-Lock slots on the bottom and sides. The
+
+### Optic
+
+| Brand          | Price  | Source             |
+| :------------- | :----- | :----------------- |
+| Vortex |  |  |
+
+I chose the Vortex Spitfire Gen 2 with 3x magnification. I've found the 3x magnification is low enough that close range acquisition is reasonably quick while still giving a bit more oomph at mediom-long ranges. I also like that it is a prism optic which prevents dot blur if you have an astigmatism. Some dislikes include the coarse adjustments (1 moa per click) and the short eye relief and small eye box.