So, you've put your rifle together. It will physically discharge a round of ammunition and send it downrange. But you're not done yet, there are still a number of small but necessary purchases to make your rifle functional. Some are obvious, some only to those of us that intend to use these firearms outside of a static range on a shooting bench.
***Forgot to mention this in the previous installment - Radian Raptor Charging Handle - I gave a mil-spec charging handle an honest try, and with the traditional "two fingers over the top" grip it works well enough. What it does not even attempt to do well is allow you to "blade" your hand past the charging handle and actuate the bolt. This easily remedied that issue, and I only chose this vs. some other options because I had personal experience with it in a friend's built and I know it would work the first time.***
Sling - Magpul MS2 - I have previously had some experience with a number of slings, of the single and two point variety. My EXTREMELY brief excursion into three point slings has led me to never recommend them or use them again, so let's table that abomination. With few exceptions I default to a two point sling. They are versatile for carrying and steadying your rifle when shooting off hand, provide a means to allow you to take both hands off your rifle without it clattering to the ground (if you need to switch to your secondary weapon, or use both hands for any other purpose), and allow you to carry muzzle up or down depending on the situation. The greatest benefit is the control they lend to your rifle that a single point simply does not. The Magpul MS2 is secured to the buttstock via a tri glide wound through the sling point, and via a QD to the handguard. This gives me a means to separate the upper and lower (I can hit the button and disconnect the sling from the upper) and if I get tied up I can shed the sling quickly. Extra points for color coordinating the sling to the furniture (OCD is a thing.)
Backup sights/Irons - Magpul MBUS - The MBUS sights are affordable, and appropriate for their intended use. MUCH better sight options exist if you intend to use irons more often than I do, but as a backup to a more capable and sophisticated sighting system. They are plastic, so if durability is a concern you may opt instead for the Magpul Pro sights which best I'm aware are made of metal.
Primary sights/The Great and Endless debate - Vortex Strikefire 2 and Vortex VMX-3T - I debated, really debated, using a red dot and magnifier (separate debates) vs. using a Vortex 1-6 or similar scope. My father, who's AR build is fairly similar to mine in parts and phylosophy, did opt for a Vortex Strike Eagle 1-6, so I have an opportunity for some very direct comparisons.
The Vortex Strikefire 2 is a notorious robust and reliable red dot from Vortex's catalogue, as such being backed by a company with a reputation for not screwing up products and an unbeatable warranty. It has a 4 MOA dot which I initially was concerned may not be a fine enough point of aim, but I referred back to my phylosophy of use. I don't see iron sights as being too imprecise, and the front sight post isn't dramatically different in size from the red dot as mounted on my rifle. I was able to string together perfectly respectable 2-3" groups at 100 yards, and engage an 8" plate mercilously. The red dot does run off of a single CR2 battery vs. the more common CR123, but I found them available and stashed a spare in my pistol grip. Note, when things run on batteries, have spares onboard the rifle if at all possible, in your kit if not. Extra points for the cantilever lower 1/3 cowitness mount included with the red dot.
The VMX-3T is Vortex's second go at a 3X red dot magnifier. I did opt, as many do, to reverse the usual arrangement of the included flip-to-the-side mount (usually flips to the left, mine flips to the right, call it personal preference) which was easily accomplished. I found the magnifier to be clear, the mount to be very stable, and the limited magnification to provide just enough extra visibility to stretch out the effective range without slowing down target acquisition. I would never call this a replacement for a 1-6 scope, but it does give you more tools in your toolbox for a red dot. With the two optics paired together, engaging 8" targets at 100 yards is easy. It was certainly no chore before, but the magnifier does give me a greater degree of target ID and placing my shots than I had without it. It also gives me a bit better clarity at intermediate ranges. It will not give you that fine point of aim to make sub MOA groups, but it will stretch your natural eyesight out that much farther. Mags, cause it ain't a semi auto without them - C Products Defense stainless steel magazines - I picked these up silly cheap from SGAmmo when they had some in stock. They are a literal clone of GI mags, minus the anti-tilt follower and the steel bodies vs. aluminum. Perhaps a little heavier, but hopefully also a little stronger, they have proven bomb proof in their reliability. I'm less picky about a person's choice on mags as long as they run them enough to be secure in their reliability or weed them out as "range only" mags. All the junk in the buttstock/pistol grip - The Magpul buttstock, as many fixed stocks, has a built in storage compartment. So does the Magpul pistol grip. I have managed to cram a few scraps of old tee shirts to use as cleaning rats and patches, a small bottle of oil(Ballistol), a GI cleaning kit (leftover from my Army days) complete with a chamber brush, and spare batteries for my light and red dot. I would encourage anyone to use onboard storage for bare minimum gear to service the rifle, just so it's always there. I also have a RATS tourniquet wrapped around the buttstock (not in the location pictured, it slipped and interfered with the charging handle) because Murphy is ever vigilant and things happen. What I set out to build was a jack of all trades rifle, something equally capable of home defense as defending a neighborhood. I don't see my max engagement range often exceeding 50 yards, 100 being fairly optimistic, and 200 being extraordinarily rare. The 18" barrel gives me the velocity to insure terminal ballistics, rifle length gas system and A2 buffer makes for a soft shooting rifle that won't choke on odd ammo choice, quality parts insure I don't have to worry about premature failures, and a flexible optics package that grants me faster target acquisition than irons without any loss in capability in my chosen envelope. The rifle functions, and is proving accurate as I spend more time behind it. What else can I tell you about? Any interest in me talking about my load development as I tackle this new cartridge? - Phil Rabalais