Watercooler 5/24 Open Thread: The Lunch-Hour Lower: Lessons Learned

#NotInMYNamewatercoolerWelcome back to another installment of the Watercooler, RedState’s daily Open Thread! Today, we’ve got the second installment of our Lunch Hour Lower project. Fair warning: if you are prohibited from owning a firearm, or think the citizenry should be prohibited from same, STOP READING NOW. There are plenty of other things worth reading today, but this one is not for you.


The Lunch-Hour Lower: Tools and Lessons Learned

Tools Needed:

  • Cordless drill, or better yet a small drill-press. I suggest one that comes with a charger and at least two batteries; typical work sees a battery drained every day if you’re drilling most of the hour.
  • Small vise
  • Jig. EP Armory has an inexpensive and simple jig, which is what I used. If you’re using a cordless drill, I suggest also looking for a second jig with two rows of holes for drilling the FCG pocket, rather than just the outline.
  • Bit set, preferably from your jig manufacturer
  • A couple extra bits and a set of drill-stop collars; I added 1/4 (a nice intermediate size) and 5/16 (width of trigger slot) to the mix
  • Blue painter’s tape
  • A good ruler, measuring in both inches and millimeters
  • Screwdrivers, hex-drivers and Allen wrenches
  • Receiver blank: this is what you’ll be working on. I suggest you start with a polymer lower for your first, especially if you insist on doing it with hand tools as I did rather than at least using a drill-press and vise, and pick up at least two or three with the expectation that your first and maybe second will come out junk. If you’re going to write it off from square one, at around $25 each EP Armory’s are affordable practice parts.
  • Lower Parts Kit: you’ll need at least the selector, trigger, hammer, disconnector and their associated springs and pins to test fit and function. The work’s not done until these parts function as intended, with the disconnector releasing the hammer when the trigger is pulled but grabbing onto it and not letting go if you push the hammer back without releasing the trigger, then disconnecting on trigger reset.
  • Testors or similar modeler’s contour putty

Lessons learned:

  • Buy *at least* two blanks. Preferably three or four. Expect to be less than satisfied with your first–anywhere from “not proud of” to outright junk. If you come out with a usable lower on first try, lucky you to have a spare for your next build, but there are some things here that have to be learned by trial-and-error experience. The lower pictured last week I might use for .22LR or weak .223 as a range-toy, but even with how little of the firing stresses an AR lower actually bears, no way am I betting my life on that one with full-power 5.56 NATO rounds, especially not the good Reach Out and Smack Some Daeshbag Mark 262s.
  • Before you even start work, break out the putty and fill in that “Auto” selector marking. We’re not building anything select-fire capable here–I’ve known of cops who went for the arrest even with *clearly fake* markings on semi-only M16 replicas, to say nothing of using M16 three-position safeties or bolt-carriers–and better safe than sorry. Plan on giving tat area a dab of paint after you’re done.
  • A vise is an absolute must. If you can’t bolt one down, buy a little drill-press vise, I think Walmart and Sears have ’em for twenty bucks. This’ll be my next tool purchase
  • If you’re using a cordless drill, make sure to look for a jig set with lots of little holes in its top-plate rather than just the Fire Control Pocket outline. As noted below, this is the one big thing I’d change about the EP Armory jig I used–but if you have a friend who owns a metalworking business or home machine shop, it shouldn’t be that difficult to have them make you a set of add-on top plates with guide holes for smaller bits.
  • DO NOT rush to use the end-mill, even if you have a hole big enough for it! It can and will chew up your top-plate. The mill has a smooth section above the cutting surfaces; this smooth area is what you want to have bearing on the edge of your jig’s cavity. Cut to depth using your smaller bits, let the 3/8″ do the heavy lifting, then once you have things to final depth bring in the end-mill as The Closer.
  • For things like the selector tail at the rear, or the trigger slot, better to start the hole at the center and then recut toward the ends; otherwise you’ll leave a thick web of material that will cause the drill to fight you more than it does the stuff that needs to go.
  • If you feel any resistance, BACK OFF IMMEDIATELY! It means you’re probably trying to go too deep this pass.

When the time comes to proceed with assembling the finished lower into a complete set of firearms, Brownells has a simple, understandable complete set of assembly instructions on their website–these were good enough I didn’t even need to go to their Youtube videos. But we’ll discuss that, and a few helpful books to get through building your AR, another time… like after another FAB AGF-43S folding grip and a few other important parts arrive.

Gear Review: EP Armory jig, bit set and receiver blank

In a nutshell, these are not the Lamborghinis of the EPL community, but I’d characterize them as more like a Honda Civic–a starter, or a sampler-kit where you can try DIY and if you like it either stick with it or progress to more advanced and expensive hardware, but if the bug doesn’t bite and you decide finishing your own blanks isn’t for you you’re not out much. (Granted, I caught them on sale, but I paid around $100 for the jig, the bit set and two lowers, though I did have to make do with a Godawful shade of lime green to get a better price. For five bucks off each, I got a can of Rustoleum that can fix that…)

To start with, the jig screws together around the lower, forming an upside-down cradle–two screws join the sideplates, passing through the magazine-catch and takedown-pin holes, and then four more screws join the top plate to the sides. (The top plate has two holes: the small one is for cutting the trigger slot in the bottom and works best with a 1/4″ or 5/16″ bit, while the big one is for cutting the main fire-control pocket. Contrary to what I first thought, it’s better to focus on the pocket first, THEN cut the trigger slot.) The one thing I would change about this jig set is that I would add three more top-plate sections for 5/32″ (starters, and thinning some of the “points” around the edge), 1/4 or 5/16″ (intermediate) and 3/8″ (main material-removal) drilling.


The bit set gives you a 5/32″ and a 3/8″ regular bit, and a 7/16″ end-mill. A good start, and a steady hand might Git-R-Dun with just those three, but since I wanted some intermediate options for pilot holes a trip to Home Depot was in order to build on the provided foundation.

The blank itself is simply a large piece of injection-molded plastic in the shape of an AR15 lower receiver, but with a solid block where a trigger pocket would normally be. It’s basic, kinda no-frills–I don’t particularly like the integral triggerguard, but can’t imagine any way they could have done the “ears” to mount a normal one–but for a first lower to start learning on, it shines in this little entry-level niche.

I would not call these the absolute best parts and tools money can buy, but I would call them the best value-for-money someone just starting out and unsure if the EPL “make your own gun” thing is for them could ask for. And since some lowers don’t fit the “better” options thanks to various reinforcements adding material that interferes with jig fits, this simple little number has a better chance of slipping them in and getting ’em done where the “big boys” from Juggernaut and 5D Tactical might not. I have no regrets about buying these, and would do so again–but on the rewind, I’d have talked to my buddy “Metal Monster” about having extra top-plates made first.


This Week In History

  • Sunday, 5/21: Pro-slavery terrorists burn Lawrence, KS, 1856; American Red Cross founded, 1881; Lindbergh (1927) and Earhart (1932) land on respective first male and female trans-Atlantic solo flights
  • Monday, 5/22: SS Savannah sets sail on first trans-Atlantic steamship voyage, 1819; Associated Press formed, 1900; loss of nuclear submarine USS Scorpion, 1968
  • Tuesday, 5/23: South Carolina ratifies Constitution, 1788; Mexico declares war on us, 1846; first version of Java  programming language released, 1995
  • Wednesday, 5/24: Dutch buy Manhattan, 1626; Morse sends first telegram, 1844; Brooklyn Bridge opens, 1883; Sikorsky flies first successful single-rotor helicopter, 1940
  • Thursday, 5/25:  First and only firing of “Atomic Annie” nuclear artillery, 1953; JFK addresses Congress calling for lunar exploration, 1961; Star Wars premieres, 1977
  • Friday, 5/26: Congress passes Indian Removal Act, 1830; Edmund Kirby Smith in Galveston last Confederate full general to surrender, 1865; Civil Air Patrol established, 1948
  • Saturday, 5/27: First assault on Port Hudson’s defenses, 1863; last Ford Model T built, 1927; F-4 Phantom II first flies, 1958

Today’s Birthdays: Wright Bros. engineer Charlie Taylor, 1868; confectioner H. B.  Reese (the peanut-butter cup guy), 1879; musician Bob Dylan, 1941

Holidays Around the World: Canada celebrates Victoria Day, Eritrea observes their Independence Day and Belize has Commonwealth Day.

This Week In History is compiled with assistance from History.com and Wikipedia. Something interesting not listed here? Please share in the Comments section–this is an Audience Participation Encouraged featurette.

Gratuitous Gun Giveaways

*Note: FMG Publishing giveaways require you to provide an FFL dealer’s info at entry. Aero Precision and Primary Arms giveaways give me one entry each per person who uses my referral link.

Quote of the Day

While coined to refer to some collector snobs also an apt description of today’s Left, from a friend in the Transformers collector’s community–it’s a few years old, but more fitting now than ever.


“Being offended gives them a sense of moral superiority. It does not matter what they’re *actually* offended about.”–TFW2005 member “Kungfu Dinobot”

As always, the Watercooler is an Open Thread, so the floor is all yours…

#NoQuarter #TheParty’sOver

By WarX, edited by Manuel Strehl (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons
(Image by WarX, edited by Manuel Strehl at Wikimedia; used under Creative Commons Attribution license)


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