In Part I we discussed the upper receiver and some thoughts that go into building a budget minded AR-15. Now we’ll head down to the lower receiver and finish with attachments. Arguably most people will say that upper receiver is the most important part of the weapon and with good reason. After all, the bullet does get launched from there, but like everything else it needs a good base to support it. One major problem to look out for is an excessive amount of wobble between the upper and lower receivers. Too much play can cause misfires or jams. This is where spending time researching through Mr. Google can help.
I happen to catch a sale at my local gun store and picked up a Smith & Wesson M&P15 lower. Smith & Wesson has a long storied history in American firearms history so I knew I wouldn’t go wrong. Almost before I get a lower out of the box, I’m already talking off the supplied buttstock and replacing it like most others. For me that means installing a Mission First Tactical (MFT)stock, but there are plenty of different choices for aftermarket stocks. Myself, I like the Minimalist version of the MFT stock which you see in the photo above. I like this stock because they have shaved off a lot of weight, (in the AR-15 world most weight savings is measured in ounces not pounds), it fits snug but not tight and moves freely. A note of caution here. When replacing stocks make sure you know whether you have a commercial or MIL-SPEC buffer tube.
As you see pictured above there is minimal size difference between the two, but it’s enough that a MIL-SPEC stock won’t fit on a commercial buffer tube. Although a commercial stock can fit over a MIL-SPEC buffer tube there will be a lot of play that might cause lock up problems. Other than the stock most people may choose to also replace the standard pistol grip as it can place the firing hand at a slightly odd angle. I haven’t replaced mine yet because…well, frankly I’m having too much fun shooting it!!
There are many other parts that can be replaced on the lower once you get comfortable. The trigger and hammer are popular pieces to trash and replace (By trash we mean throw into a parts bin!) as are the buffer and buffer spring. Changing out the buffer can play dividends when you start shooting different loads and run into cycling and recoil problems. They come in different weights and lengths. The word of caution here is to not put a rifle length buffer and spring into a carbine length buffer tube. Here is a sampling:
If you look closely on the picture above you’ll notice a brown lever above the trigger. It’s called a Battery Assist Lever (B.A.D.) by MAGPUL What it does is allow you to release the bolt catch using your trigger finger without changing your firing grip there by saving time. In a violent encounter milliseconds count. As we go back to the upper receiver for attachments you’ll see that mostly everybody will add some type of optical sight to their rail system along with a pair of back-up sights.
Optics help you get on target faster and bring the target closer if they are magnified. The group includes the traditional telescopic sight, reflex sights and holographic sights. The myriad of manufacturers along with different types of reticles places this discussion beyond the reach of this article and will be addressed in a future article. Suffice to say that there are major advantages and very few disadvantages to have a sight mounted to your weapon. For mine I went with a company called Sightmark. Relatively unknown I decided to take a chance on them since the price was right as they say and I was not disappointed!! For under $200 the sight stays zero firing a major caliber round (.300 BlackOut), is easy to mount and takes up very little rail space. Of course there are others out there Aimpoint and Trijicon sit at the top of the heap but Vortex is another new comer that is superb.
Electronics being what they are…they can and will fail and sometimes at the most inopportune times.
For those times their are the back up iron sights or BUIS. They mimick the sights on the original AR15/M16 platform but usually are spring loaded and flip up with the push of a button. Quality control is so good these days that electronic sights rarely fail, but if they do you’ll be glad if you have a pair of BUIS to continue the fight!!
Last, but not least in the cool factor is the rail mounted laser. Nothing says I watch military movies more than a green laser emanating from the front end of your bullet launcher. Just like electronic sights lasers can help you engage your target faster when seconds count. Try not to fall pray to the dreaded “chase the laser dot” aiming method. Lasers are a great low light adjunct but they should NOT take the place of mastering the fundamental shooting skills. Having a group of shooters wielding lasers can be a bit confusing and that is definitely not good when your pucker factor is already measuring 8.0 on the Richter Scale! Another problem with laser that electronic sights don’t have is the telegraphing of your position. Contrary to popular belief all lasers are not invisible as seen in the picture. If there is any kind of dust particles in the air the laser beam will reflect off of them. Infrared or IR lasers are available in civilian eye-safe levels but expect to spend around $700+ most times.
As you can see building your own platform can be a money saver, but it can also be a big sense of accomplishment to know that you built something that works. You can mix and match pieces to your hearts content. The AR-15 platform is the Barbie for shooters!!! So break out your screwdrivers, hole punches and hack-saws and we’ll see you in the Man Cave and Ladies Lair!!!
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