Interesting

Explain please.  

In ?

Steel AR flats shipped from the Flat Spot for $31 total.

http://www.theflatspot.net/ar-15-receiver-flat.html

You can weld them together, or you can try Super Glue.  I happen to have a lot of Super Glue on hand.  

It's better than wood, I reckon.

I think the concept is interesting. Might pick one up just for kicks!

I'd seen those before.

Hope you're up to the challenge to get one of those to work.

I can see several areas that are going to be a real PITA if doable at all.

A 0% forging and a Dremel would be easier in my book.

I ordered two after reading the thread where the poster was looking for a steel lower.  Interesting concept.  I have a wire feed so I figured I'd give it a go.  For the price it will be a fun project.  I'm not planning on tapping for the buffer, instead thinking about welding a tube and but plate assembly. I don't have anything on paper just sort of thinking it through.  Need to start sourcing the correct dimensional tubing.  Thanks for the pics, the flat spot website isn't all that descriptive.

I mainly got it as a demo for my stocks.  It doesn't have to actually work.  Rather than tapping the receiver extension threads, I was thinking of chopping a rifle tube to the length of the ACE short tube & super gluing it in.  I have no welding experience, so I was going to try superglue & throw my brother's CMMG .22"LR upper on it.

What are the worst problems you see?

Here is some dialog from the other thread.

Steel lower thread

Serial number?

Another Site, Another Thread, Same Topic

Over-rated, beside this is the BIY forum.  But since I get annoyed with replies not offering ANY help what so ever...  Try googling "80% lowers". Ares has a link on their site to ATF info.  FAQ type stuff.

You guys have to put serial #'s on your builds now?

so, you could braze these up?

Hadn't thought of that.  Maybe some silver solder?  I'm planning on spot welding, I'm by no stretch anything of a welder, but even a tack in the right spot will be fairly rigid.  As I mentioned earlier, I ordered two, so plenty of room to get the machine dialed in.

From this and other replies, I gather that serial numbers are not required on incomplete lowers. If this is the case, I have learned my new thing for the day.

80 percent or less AR lowers that are home built not for commerce, require no serial number

You are correct.  Home built Title 1 firearms don't require a serial #, unless you go to sell it down the road.  The Flat Spot claims their flats are not firearms, though they have not sought a BATFE Tech Branch letter to that effect.  After being burned on the EP Armory debacle, I took a $31 risk that BATFE doesn't raid the Flat Spot next.

I've never seen anything definitive on this.  If I'm not mistaken, the verbiage is "should" add a serial number.  I have seen many opinions on what that means, but again, nothing definitive.  Anyone?

Yes, I know, if it gets stolen, identifying markings will help, but I'm talking about "required" manufacturer markings, Manufacturer, City, State, Model, Caliber and Serial

i wonder if you could embed something like this under a 3 d printed skin

Lol!  That would be cheating!  Have actually thought about using some parts from this for the California bullet button problem on Effort Bloomburg:

http://www.feinsteinproject.org/loes/effortcalifornia/effortCalifornia.html

But yes, you could reinforce a printed lower w/ embedded steel parts.  You'd have to design the voids in the program, and stop the print so you could add the parts as you went.  That would solve a lot of issues w/ 3-D lowers.

What areas do you think will be a problem?

Silver solder????

I think getting the receiver extension boss in the exact right location's gonna be a pain in the ass.  If I was welding, I could cut it off & start over.  W/ superglue, I get one shot.  

it's STEEL, are you telling me if you super glue it wrong you can't make it red with a torch and kill the superglue?

can't soak it acetone? nail polish remover?

Oh, I could make it red & have it give off cyanide fumes.  Or for $31 bucks, say screw that, let hotdog try that, send it to you, & order a new one.  

I'll take it if he doesn't.

To answer you and jaydee54:

1. Anywhere that has two pieces of metal that require threading together whether they are parallel to the axis of the threads or perpendicular.

   i.e. the grip screw or the receiver extension threads.

   If there is any give (flex) whatsoever in the material (it is mild steel AFAIK) in my experience
   you aren't going to have an easy time threading those holes.

   Furthermore be aware that any welding close to those areas may actually harden the steel.

2. Anywhere that two holes need to be axially aligned.  

    i.e. the hammer, trigger pins, selector...etc...

    If the plates shift a tiny bit you will have to ream the holes into alignment to prevent binding of the components.
    This will in turn introduce some slop.
    Hopefully the holes are slightly undersized, then this won't be as much of an issue.

Those are my main concerns.

I'm not saying: 'Don't go for it!'  

Just don't be surprised if things aren't as easy as advertised.

1 - the receiver extension threads - ain't gonna be.  A rifle tube slips through there just fine.  Going to cut it to length of a ACE short buffer tube, and superglue it in place.  If you were going to thread that, it would need to be welded.
- the grip screw - an A2 pistol grip will be - again - superglued there.  W/o a drill press, I am not going to attempt to drill the safety detent in a superglued laminate, so the A2 PG will be permanently mounted.

2 - as I indicated above, I'm going to go w/ a Mosin safety on this.  I imagine before I glue in the 2nd side plate, I'll go ahead & have the hammer & trigger pins in place, which will be the closest I get to using a jig.  As long as I don't get any superglue on the pins themselves (this is an Aggie talking), I should be able to knock out the pins once the superglue dries over night, and install the abbreviated FCS.

No takedown pin detents, no bolt hold open, no safety.  That would require a drill press, which I don't have or I'd be doing a conventional 80% or a plastic one.  Thanks for taking the time to look @ the issues.

Hi you all. My first post. Quick intro first. Names twistie Im 55. 6 years Australian Navy weapons mechanic, 12 years Australian Army infantry Battalion armourer, collector & military firearms gun plummer . Till 1996 gun law changes (port arthur massacre ). I joined this forum because of this thread. I recently was given a set of these plates. Yeah !!!. Right a couple of things I know. I own  mig & stick welders one thing is if you use a 2.5 slainless rods in a stick welder when welding mild steel it runs almost like solder & gives a nice finish & easy  NO SLAG to clean. A thin black film that peels itself off TOO EASY !  Right grinders Ive got everything from 9inch down to little air drive dremil. The BEST general purpose grinding tool is a metabo 125mm  rechargeable handheld.  It takes 4,4.5, 5 & 9 (used down as far as you can in the 9 inch grinder discs ) inch discs. It turns at a slower rpm & is easier & more controlable. A more user friendly tool ! Slower rpm A lot less sparks too. Its really good with the "flapper" & polishing discs (press a bit harder and it removes some serious steel neatly .
After all that anybody interested in my ideas on this build? Ok sorry to just but in on this thread. cheers guys

What did you think was the appeal of an 80% lower?

 

Welcome !  And by all means, please do tell your ideas.  That's how we learn here.  

Welcome fellow squid!  What do you have to do to run ARs down there - manually operated like the Brits?

BRD is rough on my dead presidents.  I ended up ordering some AR, AK and derringer flats.  I have a pile of 80's and 0's already that "need" some time, just can't seem to kick the illness.  

ok quick fill in on laws. We have state (ownership) & federal (importation) firearms laws. First on federal laws No importation of firearms & parts without permission from your state authorities & a damm good reason. Like research & development for the military or somthing like that. State police & ownership. We have across Australias states with much the same laws. Buy when you get words like "may" "shall" " discretion" you are open to different interpretation by the different state & police authorities. In most states you cannot legally have say a 30rd ar15 or ak mag without the correct endorsement "cat A,B,C,E on your lic. More info here http://www.police.tas.gov.au/services-online/firearms/firearms-licences/firearms-licence-categories/       . One state (I will keep that secret for now) doesnt worry much about this rule. So a thriving blackmarket exists. I just paid $150 for a used O-Kay 30rd mag used. An AK 30rd $220-$300. A 70rd ak drum mag $3450. You cannot sneak mags through customs they will charge who it is posted to & our new Liberal ( our Libs are the right side conservative party) goverment has suggested 10 years jail for illegal importation   We the gun people did loose out when they banned everything in 1996. We didnt have a large progun lobby group & all (most all) stuff was imported any way. Pre 1996 laws change I owned all sorts. Olympic Arms M16 (select). olympic xm177(select), H&K 91 (semi), AR18 select fire, Browning 1919a4 (it fired 3 different rds 30-06 7.62 nato & 7.92 (8mm), Brens .303 & 762 nato,  Chatterlault 7.5mm, M2 carbine & a few others.  l then was allowed to import a deactivated new akm from England. I repaired all my oun stuff.  OH well that was the good old days. NO LIC required for any of these then pre 96.  Oh well it brings a tear to the eye now.
'
Ok the build. option one champher mating edges 45 degrees & fill the void with stainless weld (you could use mig or tig but I prefer stainless stick) & polish smoooth. Thinking of maybe drilling 4mm holes & using a steel pin & sandwich the plates. Counter sink the outside plates & weld pins in place & pollish smooth. I dont see drilling a hole for the front hinge pin & spring a real drama just a bit hard. Because I havent seen a ar15 for nearly 20 years there are some things Ive forgotten & when I ask some questions dont make fun of me please. Ex vet & ptsd problems. ok first question what size is that hole & how deep ? I will make my own pin & spring. I would like to see some good pics of a 9mm carbine bolt & breech area. Ive never seen a 9mm version. Does it use the gas system ?   Anyway thats enough for now & cheers to you guys from Tasmania

You can do 9x19mm gas DI, but most setups are straight blowback w/ a heavy buffer.

Which hole are we talking about?  About the only thing you have to drill on the flats is the safety detent hole down to the pistol grip.  You'd probably like to drill the bolt hold open pivot pin hole, and the buffer retaining pin hole, but they're not absolutely necessary.

on the front of lower receiver is two holes for the hinge pin. The hinge pin pushes out to the right. There is a small detent that secures the hinge pin. I need to know that detent size. Not too worried about the bolt hold open device hole. I got one & doesnt look too hard. The saftey detent. I think I might put a little steel there before I drill it. There is one more hole in the rear section for the break open pin I havent given much thought yet. The recoil retaining buffer pin hole Im not sure yet. I really like the blowback idea. no gas. great. Bloody frothing to see pics of breech & block

The rear takedown detent pin hole has already been drilled in the two receiver extension bosses.  You'll just have to chase that hole further into the receiver to hit the takedown pin hole.

Someone here will pipe up w/ the dimensions on the front pivot pin detent hole.

Pictures you want?

https://www.google.com/search?q=9mm+AR+bolt&client=firefox-a&hs=6if&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=oGl9U_21K8GdqAa7oYCADQ&ved=0CCcQsAQ&biw=1600&bih=720

ETA:  I think this .pdf has nearly every dimension of an AR lower except the one you're asking for:

http://www.feinsteinproject.org/loes/effortbloomberg/2007-10-17_131429_AR_15_Scratch_Built_Receiver.pdf

here's a tutorial on making a aluminum 80%er. the dimensions and drill sizes will apply.

specifically as to your question (from said tutorial)

,
The next hole I decided to drill was the front take down pin detent hole. I used a (F) #40 drill for this hole. It’s a little bigger than what is called out on the blueprint, but in my experience I would rather have this hole a hair bigger because the last thing you want is the spring or detent getting stuck in this blind hole. Like the previous hole drilled, the location of this detent hole isn’t critical either, so I used the two-line scribe method again. I clamped a flat surface to the top plane of the jig and then scribed a line at 0.250”…

AR15 80% Lower Receiver Tutorial - 1254.jpg (31650 bytes)

Instead of scribing the other line, I decided to use a 0.109” diameter transfer punch and set it against the take down pin lug…

AR15 80% Lower Receiver Tutorial - 1255.jpg (22482 bytes)

With the transfer punch against the lug and on the 0.250” scribe line, I made the center mark…

AR15 80% Lower Receiver Tutorial - 1256.jpg (17188 bytes)

The drill depth of this detent hole is 1.125” from the center mark surface. Again I locked the spindle in with the (F) #40 drill touching the center marked surface and set the drill depth to 1.125”…

AR15 80% Lower Receiver Tutorial - 1257.jpg (30686 bytes)

When drilling this hole, make sure you go SLOW, take small pecks, and use plenty of cutting fluid. If you go too fast, it would be easy to break this small drill off in that deep hole. You also want to make sure the chips are cleaned off the drill every time you take the drill back into the hole. If you don’t remove the chips, they will get compacted in the hole and cause the drill to break or walk off position. Here is a pic after the hole is drilled…

OP did you purchase with credit card?(is this place credible)

I may want a couple to toy around with.

Probably not want to use it with .223 though huh? .22lr or something small?

Wow so much info thanks guys. All I got to do is get a pic uploaded. BTW my fav of all time olympic M16 with rem 870 underneath. cheers

Yep, used a credit card, they've been in business for awhile.  They have not sought a Tech Branch non-firearm determination letter, so you run the same risk as with the EP Armory plastic 80% lowers.

I'm going to superglue it, see if it works on my brother's CMMG .22"LR upper, then I'll try my .223".  Not gonna try his .458" on this.  If it was welded, I'd try his .458" on it.

Another interesting lower build was the aluminum plate lower

I think these are the plans for that:

http://www.feinsteinproject.org/loes/effortbloomberg/2007-10-17_131429_AR_15_Scratch_Built_Receiver.pdf

There's a guy in OKC that was supposed to be doing a deal where you buy your 80% AR15/AR10 and for a price you finish it at his shop with a shop person who walks you through it so you don't ruin it.  It allows you to finish your 80% legally, even if you have no machining experience at all.  I can't remember if they did engraving too but there was some way involved to get it done.

I don't know if he ever got it started or not but it's a great idea.

Sounds like other operations that have already run into hot water.

ETA: There used to be a tacked thread here about the bolt together lowers.
The manufacturer of those was one of the first ones I remember getting some negative attention...
(six or seven years ago IRRC.)

...but then again they made it a point of baiting the .gov on other issues too...