Interesting AR Build approach

These are what's usually called a Lower Parts Kit. Most packaged LPKs also include a pistol grip and its fasteners.

These are what’s usually included in a Lower Parts Kit. Most packaged LPKs also include a pistol grip and its associated fasteners.

Lately we’ve found interesting material a few blogs that were new to us. Most of these come to us via the indispensable Gun Wire, even when the story we report is not the one they featured (any site that rates a Gun Wire link is worth exploring a little). At the curiously named Jerking The Trigger (as in, we thought you weren’t s’posed to do that), we found an interesting and different approach to selecting a Lower Parts Kit (LPK) for an AR-15 build.

I have been getting a lot of emails regarding where to buy a truly top-shelf lower parts kit (LPK). My answer has been something like, it doesn’t matter because none of them are readily available right now. However, I have given it some more thought and I realized that the days of the complete lower parts kit may be numbered – or at least they should be.

Many people buy a lower parts kit and then promptly replace nearly half of it with aftermarket parts. Why not just start with the aftermarket parts you want and then fill in with high quality components where necessary?

If I wanted to build the best rifle I could right now, I wouldn’t buy a complete LPK. I would buy a few select components and then fill in the necessary small parts with quality components.

via Build Your Own Premium Lower Parts Kit – Jerking the Trigger.

We normally use GI parts and only alter the trigger, but then, we build a lot of Retro ARs rather than chase the ever-improving (or at least -changing) state of the art. You know the old Kinks song, “Dedicated Follower of Fashion?” That’s what we’re not.

The factory parts — by which we mean Colt or milspec parts — are made specific ways, of specific materials. Aftermarket and particularly budget LPKs may not be made to that standard. Some of them are … how shall we word this tactfully? … never mind, to hell with tact. Some of them stink like a bag of homeless winos, melt under a hot stare, and are not only made of cheese, but of Cheez Whiz.

Assembling a lower receiver is not rocket surgery and needs no fancy tools (although some fancy tools help). The buffer tube, buffer and spring are sold separately because there are several versions. They may be included with a stock.

Assembling a lower receiver is not rocket surgery and needs no fancy tools (although some fancy tools help). The buffer tube, buffer and spring are sold separately because there are several versions. They may be included with a stock.

OK, that’s an exaggeration, but a small one. Most of the parts that go into an M16 or M4 lower receiver, and that, perhaps, should go into your AR’s, are investment-cast to near-net shape and machined to finish. Solid and roll pins are made differently. The solid pins are centerless ground for a precise fit, which is an extremely high-throughput manufacturing process highly developed by the automotive industry. The disconnector is an exception: it is often made by laser cutting; that’s not the process in the milspec technical data package but laser-cut disconnectors have been accepted. After manufacturing has completed the parts in-the-white to final size, they are heat treated as needed and finished with a phosphate coating.

Colt parts are good, but even before the current crisis made everything unavailable, quite expensive — about 250% the price of a budget kit. Surplus military parts are less available than they were; the military is now required to destroy rather than dispose weapons parts.

There’s a lot to be said for choosing a vendor at least committed enough to their product to put their name and phone number on the package. The bigger name, the more confidence you can have, especially if the vendor has military contracts (Bushmaster, Colt, Remington for example) and the parts are factory-tagged or labeled as milspec.

In the real world, most civilian AR users will sell their ARs to pay their nursing home bills before they wear out any of an AR’s wear parts. We’re accustomed to seeing military ARs that have soldiered for 40 or 50 years with substandard maintenance, and they’re still ticking over.

Two more things to think about before you take the link’s approach to building a premium AR lower.

  1. First, don’t expect to recoup most investments in superior parts. Even though we’ve tried to make the case for paying $125 for a quality version of the $50 LPK, for example, you can’t expect an AR buyer to pay more for the resulting AR. In fact, the more you customize, the harder the sale will be; this is partly because the next buyer’s tastes will not perfectly match yours, and partly because whatever’s “hot” right now might well be a fad and not half as cool as whatever’s hot next week.
  2. Second, the milspec parts have been the lucky recipients of hundreds of subtle engineering changes and literally billions of rounds and millions of guns worth of torture testing. The latest aftermarket trigger or safety? Maybe not. (We’ve seen ambi selectors held together with a screw that backs out from the vibration of firing. Testing FAIL).

But our bottom line on this article is that it’s an interesting approach; it gets the gun built exactly the way you want it while minimizing the scrap parts that wind up in your spares bin.