The AR-15 and everything AR-15: A Primer

Another AR-15 Primer By Gingerbread Man.
Purpose: Assistance in creating a no non-sense defensive carbine that is affordable, accurate, reliable and durable. The AR-15 can be built in sub components making the purchase and construction of the AR-15 very easy to accomplish. The vast majority of other platforms must be purchased as a complete unit which is not the case with the AR-15. Each individual part can be purchased off most shelves of larger gun shops. Spreading the build cost out over months makes purchasing a good defensive carbine with in the reach of even the tightest budget. Can’t buy anything this month, not a problem; put your build on hold. You are in charge of the pace of your build. However, as a general recommendation the lower receiver should be bought first. This is not an overly expensive component and generally cost $100 or less. These are my general recommendations for a defensive carbine. These recommendations are meant to inspire new comers on how’s and the whys to build the AR-15 into a defensive carbine.

1. A good flash hider. I recommend Vortex, Vltor, ACC and a plain ol' A2 isn't horrible. No comps or brakes please. Comps/Brakes increase noise and flash, the exact opposite of what you want in any defensive situation. The increase in flash is blinding to the user in a low light/no light event. The increase in noise only further damages hearing if you are forced to discharge the weapon. These flash hiders general run about $60 save the A2. The A2 is generally $10 and the most affordable option. 

2. A light weight or govt. profile barrel. I believe that a lightweight barrel is worth the extra cost. It's going to save lots of weight off the front end and most semi autos are not going to get hot enough to affect shifts in the zero of the rifle. If a light weight can not be found, a govt' profile is the second best. Unless it's a dedicated Designated Marksman Rifle, avoid medium or heavy profile barrels. It's just weight and do not increase accuracy. I easily get all necessary accuracy out of my light weight barrels. Make sure this barrel is made of 4150 steel and if possible, cold hammer forged. Nitride coating is great and generally made out of 4140 steel. This is the exception to getting 4140 steel barrels. The defensive carbine must have a chrome lined bore and chamber. These increase barrel life and keep accuracy at an acceptable level. 

3. A good 2 point sling. I like VTAC and ARES Armor. More importantly the sling must be set up on Quick Disconnect (QD) and on the side of the rifle. The rifle should be able to be slung across your chest. You can run a GI web sling but it has to be mounted on the side of the rifle. If you use a GI web during a class make sure you wear a polo or collared shirt to protect your neck from rubbing on the sling. QD sling mounts are necessary because the world is full of things that can catch the rifle. If the rifle is hung up the easiest way to get the rifle off is to hit the QD button and get the rifle off. QDs are not for rearranging the mounting points on your carbine. It should be set up on the side of the rifle, one point on the front of the hand guard and the other on the butt stock. It should be properly adjusted to fit the user. Troy, Midwest Industries, Daniel Defense and Gear Sector make excellent QD mounts that attach to 1913 rail pieces. 

4. Quality flat top upper with M4 feed ramps and lower. M4 feed ramps help greatly with feed and chambering the round. There are a lot out there and generally not a big deal. If it says R Guns, don't get it, this is the only company that I’ve heard across the forums have poor quality and poor customer service. These should be properly anodized inside and out. Anodizing increases durability and wear characteristics of the rifle. There can be sight wobble between the upper and lower. If the wobble is excessive an accu-wedge will cure the wobble. Wobble does not affect accuracy nor functioning, it’s just wobble and can be annoying. 

5. A dedicated weapons light. I mount my 100-200 lumen surefire G2 in a VTAC mount. Wait its plastic! Yes, but it's robust and if I get it caught on something, the mount will break first, not the light or bend my rail. I mount my light so that my support side thumb and can intermittently operate the light. The light can be mounted either vertically, angled or horizontally however it should be able to be operated by your thumb. Stream light makes a great 150 lumen LED light that is about $50. This is about the best option on a budget build. Well, more lumens the better right? No, not at all, with lights you want a sweet spot on the lumens scale that isn’t to low which doesn’t throw enough light and won’t illuminate an area. Too much light and you get light reflecting back at you which can be blinding to the user. Test yourself by taking your light while in a low light condition and after your eyes have adjusted to the light level flash your light at a wall. If this cases a blinding effect then you have too many lumens. Make sure when mounting the light it’s forward of the front sight. If not you can get light case onto the sight. 

6. I recommend a free float tube. If that just isn't in the budget a Magpul MOE work just fine. As far as free float tube the best I've found taking price into account is the Troy VTAC series. The come with three rail pieces and are strong. One of these rails has a QD sling mount built into the rail piece. The rail should be long enough to cover your gas block. The free float tube relieves pressure on the barrel which assists the barrel harmonics and decreases the likelihood of zero shifts as the barrel heats up. Furthermore, the free float tube increases the barrels ability to cool. The opening at the front of the barrel and the vents assist in this process.
The MOE Magpul hand guard (HG) is the second best option and generally much more affordable. It’s a traditional two piece HG that has a top and bottom. The MOE HG has the ability to easily mount rail pieces at the 230, 6 and 930 positions on the rifle. I recommend either 930 or 230 positions for mounting the light depending on the dominate hand of the user.
The heat shielding of the MOE is superior to the A2 style. It directs the heat upwards towards the top of the HG where the user’s hands are not present. The A2 directs heat up and down at the support hand.
The A2 lacks the ability to easily mount 1913 rail pieces thus diminishing the ability to mount a light. The failings of the traditional HG system are it creates hot spots on the barrel that can increase zero shifts. These hot spots are generally located behind the gas block and at the barrel nut. While not the end of the world it’s best to have the barrel as cool as possible to decrease wear. It’s not necessary to have the barrel cool to the touch but it shouldn’t get smoking hot.
A final note, avoid quad railed HGs. They are generally bulky in girth, heavier while offering nothing in return for this weight and cost more. These were designed to run light, lasers, IR illumination and night vision. As a civilian user you do not use or need these items. 

7. A fixed front sight and rear sight. A flip up rear is okay if you're running optics like a red dot or a 1x4 scope. Quality sights are Troy and Daniel Defense. Running a fixed front sight base is fine and the most durable front sight solution because it’s pinned to the barrel. 

8. Good magazines. PMags, USGI that aren't 40 years old and run over by a truck and Lancer mags. Magazines are the heart of the carbine. Using poorly made or suspect mags will destroy the reliability of an otherwise fine carbine. Furthering this line of thought, test your mags with your home defense ammo in your rifle. Yes, there are some combos that will not play well together and a defensive situation is not the time to learn if your rifle works or not. 

9. Lube. It's a mechanical device. Lube it. I lube with lithium grease and Breakfree (BF). I use about a pea sized blob of grease on the bolt/bolt carrier group. I wipe it all over then I add a few drops of BF on the bolt and into the two holes on the side of the carrier. I also wipe the buffer with a small amount of grease and every 3 months I add a drop of BF to the trigger group. That's all that necessary to keep your AR lubed. 

10. A quality lower parts kit. Buy this from a reputable seller and make sure it's US made. The US makers generally have quality standard they must use in order to sell these items. These qualities of the items must be present in order in maintain reliability. 

11. A good ergonomic grip that fits your hand. Not what is the newest and coolest. I'm a big fan of the Magpul MIAD because it can be adjusted to suit the shooter. The Magpul MOE grip is a lower cost alternative that generally fit a medium glove hand. There are other high quality options and nothing wrong with the plain jane A2 apart from it generally doesn’t fit most users hands. 

12. An 6 position adjustable stock. Magpul and Bravo make good ones. Stick with the B5 and the CTR. The USGI model work well. Avoid big heavy adjustable ones. It's just more weight. One thing that must be present is the side QD sling loop. I prefer and recommend a rubber butt pad on the stock. This is not for comfort or recoil reduction, it’s a grippy area that helps keep the rifle in your shoulder. The M4 style can be slippery and move in the shoulder causing shots to be thrown. 

13. No ambi controls and no over sized mag releases. There are techniques to over come support side manipulations. Learn them, unless you're naturally a south paw, don't spend money on these. Buy ammo and learn to run the rifle. Simple searches on Youtube will fit techniques on running the AR without ambi controls. Over sized magazine releases can easily be hit due to the large surface area and eject the mag from your rifle. You’re not in a competition where fractions of seconds matter on mag changes. 

14. Charging handle. Ditch the standard style. I strongly recommend the Bravo Company Machine charging handle. They are much stronger and ergonomic making manipulating much more positive. 

15. The stock trigger is fine. Learn to work it and the more you shoot the rifle, the more the trigger will smooth out. Ammo and range time over specialized gear. Unless you’re shooting very smaller groups the lighter trigger will not help you shoot better. 

16. Bolt Carrier Group (BCG). This is an area of contention. Some people claim that your bolt must be a magnetic particle inspected (MPI) and high pressure tested (HPT). While this maybe true with machineguns I’m not entirely sure it’s necessary for an AR-15. I advise that the BCG should be for another reason, that being fitting. Generally, non-MPI/HPT BCGs are made by a company that does necessarily have the best specs on the bolt. They believe close enough is good enough and I believe this is incorrect. If the BCG isn’t within specification it will cause and induce excessive wear. The AR-15 is a system that relies on close tolerances which is a factor in its accuracy and functioning. With this in mind, companies that take the time to MPI/HPT take the time to make their bolts within specifications. Therefore, to have a reliable self defense carbine the MPI/HPT bolt is a must and not excessive in cost.

These are general recommendations for the novice user interested in the grand world of the AR-15. I’d also like to make this user aware that each rifle should have a minimum of 10 mags per rifle; 4 for training, 4 for duty/defense use and 2 spares. If one fails it should be replaced.
I hope this is of assistance to a new user or a individual pondering the AR-15 system.

I'll be updating this thread periodically and I will add some pics.