AR-15 sheet metal and tube upper receiver

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All very nice Auto-Cad renderings, or whatever program you are using.

But you do realize a direct impingement system like that last one would be carbon fouled tight shut and fail to function in one magazine don't you???


rc
 
rcmodel said:
All very nice Auto-Cad renderings, or whatever program you are using.

But you do realize a direct impingement system like that last one would be carbon fouled tight shut and fail to function in one magazine don't you???


rc
Click to expand...
True, someone has tried a similar idea already.

As to the receiver. If you are going to stamp the upper, why bother with the insert? You can stamp reliefs in the side wall. Then make a simpler front trunnion and plug weld it in place.

test_zps31dj8sl8.gif

That would save a lot of weight.
 
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thought about that already, the flutes in the trunnion are larger than they appear, about the size of the inside of an AR-15 gas tube, also the whole front end will be removable for cleaning

if the shoulder of the barrel isnt too large, say youre making a 5.56 rifle and used something with about a .8125" shank and 1" OD shoulder or even a 23mm barrel for an AK youd be able to move the axis of the barrel closer to the bottom of the 1.5" steel tube, enough to fit an FAL gas piston underneath with a height high enough off the shoulder of a barrel that you could potentially feed the gas system with an AR-15 low pro gas block

so.. 1.5" tube, lower bore axis to fit a larger gas system, say you build a tappet into the trunnion you can feed from an AR-15 gas block and tube and you could make a really simple yet compact 5.56 rifle in a tube
 
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lysanderxiii said:
True, someone has tried a similar idea already.

As to the receiver. If you are going to stamp the upper, why bother with the insert? You can stamp reliefs in the side wall. Then make a simpler front trunnion and plug weld it in place.

test_zps31dj8sl8.gif

That would save a lot of weight.
Click to expand...
this was actually the first attempt i made, but clearly the stamping then becomes significantly more complex and out of the realm of most individuals to produce, also in practice it didnt work all that well because to get the necessary dimensions on the inside of the receiver it generally threw off the dimensions of the outside of the receiver enough to make it a bit more of a PITA, also so theres not a huge gap between the carrier and outside of the receiver for stuff to get in, a piece is welded around the ejection port to close the gap

heres the rendering of that earlier attempt

BFo9em7.png
tWUtZqL.png
 
He's not talking about the gas passages. It's about the the clearance between the carrier shroud and the extension and the carrier and whatever surrounds it.

Another thing, you re going to have a big hole in the side where the spent cases go, you are going to lose a lot of gas pressure out that hole, and do you really what 35,000 to 40,000 psi gas blowing out a hole that big?

(If that hole in the second image is the gas port 40,000 psi is conservative.)

Oh, and one more thing about the AR-15 bolt carrier and debris relief...

Untitled_zpsc9bb2hjn.gif

The fact that the carrier only rides on those four rails is why it can get away with running in a simple round hole.
 
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justin22885 said:
this was actually the first attempt i made, but clearly the stamping then becomes significantly more complex and out of the realm of most individuals to produce, also in practice it didnt work all that well because to get the necessary dimensions on the inside of the receiver it generally threw off the dimensions of the outside of the receiver enough to make it a bit more of a PITA, also so theres not a huge gap between the carrier and outside of the receiver for stuff to get in, a piece is welded around the ejection port to close the gap

heres the rendering of that earlier attempt

BFo9em7.png
tWUtZqL.png
Click to expand...
A few questions.

1) Why did you pierce the stamping? you could have just made radii at the end of the depressions.
2) Why did you add a weldment in the ejection port? You could just make the OD of the tube smaller, round down the edge and put the ejection port back.
3) You are trying to fit a steel stamping to an aluminum forging/machining, why are you trying to get perfect aesthetics? You are going to have to make it either very heavy or very expensive to achieve that.

In order to make a stamped anything you are going to have to make some rather complicated dies and you aren't going to fold it in one pass, even your first posted design would require at least two pressings, more likely three.

If you were planning for people to make the dies as well as do the folding, then machining the whole upper out of a square block of aluminum would be less work for the individual 'garage' (and would require less machines). If you were planning to supply the dies and have them do the pressing, yes a simple dies would be beneficial, but pressing just a round shape is more difficult than it seems and beyond most people garage abilities (It's not like bending a rectangular channel like an AK receiver). If you were planning to supply pre-pressed parts, then a complicated dies is of no consequence, as you only need make one set of dies.

I don't mean to rain on your parade, or poo-poo your ideas, but do you have any experience pressing anything beyond a simple rectangular channel (AK receiver)?
 
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MachIVshooter said:
Correct. But that doesn't mean you can't take from their simplicity and build something that handles high pressure cartridges.

You should examine some of the Browning and Pedersen recoil designs. Those would be much more suitable for adaptation to expedient designs than rotating bolt gas operated or roller delayed blowback rifles. Remember, a lot of them were built in a small home shop in the beginning!
Click to expand...
Even the first AR-10 was build very simple.... (top)

20z6ueg.jpg
 
lysanderxiii said:
A few questions.

1) Why did you pierce the stamping? you could have just made radii at the end of the depressions.
2) Why did you add a weldment in the ejection port? You could just make the OD of the tube smaller, round down the edge and put the ejection port back.
3) You are trying to fit a steel stamping to an aluminum forging/machining, why are you trying to get perfect aesthetics? You are going to have to make it either very heavy or very expensive to achieve that.

In order to make a stamped anything you are going to have to make some rather complicated dies and you aren't going to fold it in one pass, even your first posted design would require at least two pressings, more likely three.

If you were planning for people to make the dies as well as do the folding, then machining the whole upper out of a square block of aluminum would be less work for the individual 'garage' (and would require less machines). If you were planning to supply the dies and have them do the pressing, yes a simple dies would be beneficial, but pressing just a round shape is more difficult than it seems and beyond most people garage abilities (It's not like bending a rectangular channel like an AK receiver). If you were planning to supply pre-pressed parts, then a complicated dies is of no consequence, as you only need make one set of dies.

I don't mean to rain on your parade, or poo-poo your ideas, but do you have any experience pressing anything beyond a simple rectangular channel (AK receiver)?
Click to expand...
the ends arent "pierced" just rendered that way because its easier to sketch out quickly, thats all, and it could be possible to indent the area of the ejection port
 
ive been thinking of using that tube inside a tube idea to make an expedient straight-pull bolt action in .308 designed to use savage 10 bolts and barrels and possibly $5 G3/HK91 mags
 
Autopistola said:
I dig this kind of stuff. Ar-18, expedient stampings.

Need a poor man's ARAK
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how about this? a poor mans FN SCAR, the body of the receiver is based on an octagonal shape, the trunnion and bolt is an octagon, oprod is .5x.5" square steel bar and the lower receiver is an AR-15 lower only modified by hacking off the buffer tube section to replace it with a piece thatll better close up the back of this receiver.. my idea was to use an ACE modular type of interface on the back of the new lower receiver section to use side folding adapters

z5M4MsW.png
krLY0Uc.png
 
I'm putting my money on none of these ever being built. Let me use that thing I have readily available ($30-$40) and go to my computer and turn that into a real, in the flesh upper receiver in 2-3 days.

For a fun project to see if it can be done, go for it. This is an absolutely horrendous idea for the average Joe in his garage. It's far beyond a simple jig and a vice/hydrolic press. Unless you're going to stamp a bolt carrier, and a trigger group, and a barrel, etc there is no point. You still are dependent on mass produced parts and should the main producers stop due to legislation, it's going to stop all the other small, and mandatory parts. So this option is just as dependent on those manufacturers as a standard build. A standard upper is obtainable by the average Joe, this is not. A standard upper has proven reliable, this has not. I continue to fail to see where you've accomplished any goal you've stated.

Don't get me wrong, if you want to play and tinker with designs, do that till the cows come home. It's always fun to see a new twist or path and to do it yourself and actually understand how and why things are how they are has value. This idea simply is never going to have a period of time where it's the best route for the common man to go about an upper receiver, which seems like the original intent.
 
you know what id love to achieve?.. a rifle that offered all the modularity and customization of an FN SCAR for something you can buy for $500 or make yourself for less
 
you know what id love to achieve?.. a rifle that offered all the modularity and customization of an FN SCAR for something you can buy for $500 or make yourself for less
Click to expand...

A modular & highly customizable rifle that can be had for $500 or less?

That'd be the AR.
 
yeah, except you have to damn near disassemble the entire rifle to change the barrel, youre stuck with the same magazines, the ambidexterity on them is pretty poor as well.. when im finished i'll have one that surpasses the SCAR on modularity as i will also probably add interchangeable magazine wells to it as well.. ive considered having a single rifle capable of handling both a .308 and 5.56 magazine well and barrels in a single platform
 
ive considered having a single rifle capable of handling both a .308 and 5.56 magazine well and barrels in a single platform
Click to expand...

Colt beat you to it

http://www.colt.com/Catalog/Military/Products/ColtModularCarbineCM901.aspx

Please understand, I'm not trying to discourage you or downplay the importance of thinking for yourself. I just feel that you need to maintain some perspective. Small arms are a very mature technology; the only real advances in the last half century have been in materials and manufacturing methods that reduce weight, size and cost. Just about every innovation in design has been done. The practical ones became production guns, and there are thousands of patent files that are the designs which proved to be unfeasible.

Tinker for fun, to make something that you can't buy. I'm working out the details on a post modern looking 10" barreled over/under .45 Colt/.410 pistol that I'll start machining from 6-4 Ti and 7075-T651 aluminum as soon as I get a break from life. Novel design? Not really. It's an overgrown hammerless derringer. It'll be neat, though. We just have to remember that there's not much new under the sun with small arms design or cartridge development, so these things we do, we do for personal gratification.
 
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justin22885 said:
yeah, except you have to damn near disassemble the entire rifle to change the barrel, youre stuck with the same magazines, the ambidexterity on them is pretty poor as well.. when im finished i'll have one that surpasses the SCAR on modularity as i will also probably add interchangeable magazine wells to it as well.. ive considered having a single rifle capable of handling both a .308 and 5.56 magazine well and barrels in a single platform
Click to expand...
Yes, playing with a drafting program is fun.
193800020-20Rifle20T193E8_zpsm7wc2mm4.gif
But, playing in the machine shop is more enjoyable....
13A%20-%20Complete%20Right%20Side%201_zpsyzmdgmj3.gif
After all, it can lead to something new, like the ARAK. But, if you plan on production, and venture away from existing components. like bolts and bolt carriers, I would strongly suggest you find machine shops and heat treat shops and get an idea of the cost of manufacturing critical components. Especially, for a high power cartridge. The forces and accelerations are massive...
 
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you know what id love to achieve?.. a rifle that offered all the modularity and customization of an FN SCAR for something you can buy for $500 or make yourself for less
Click to expand...

In a perfect world that might be achievable. The reality though is that the only reason an ar can be had for $500 is standardization and huge mass production. If you paid yourself $5 per hour for all the time you spend on your hobby you could easily buy a FN SCAR. It is the marketplace that determines these things. One must give credit to the genius of the firearms inventors of the past. As others have said the current firearms are already very refined and simplified for what they do.
 
Casefull said:
In a perfect world that might be achievable. The reality though is that the only reason an ar can be had for $500 is standardization and huge mass production. If you paid yourself $5 per hour for all the time you spend on your hobby you could easily buy a FN SCAR. It is the marketplace that determines these things. One must give credit to the genius of the firearms inventors of the past. As others have said the current firearms are already very refined and simplified for what they do.
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face is, FN could sell you the SCAR for under $1k and still turn a profit.. they use an incredibly simple cost-saving technique that unfortunately only benefits large factories and that is the upper receiver, the heart of the SCAR is essentially an aluminum extrusion that comes out as one long piece that gets sliced up into multiple upper receivers.. only very little machining is needed for things like the ejection port, vent holes, etc

of course, FN has no reason to sell them cheap.. what allows ARs and AKs to be cheap is not just the ability for a factory to put them together inexpensively, but the competition that forces them keep their prices low, there isnt just one factory producing AR-15s or AKs because there really isnt any copyrights holding people back from producing them.. THAT is why AKs and ARs are so cheap, and being inexpensive leads more people to buy them which leads to a bigger demand in the aftermarket as well

so if you want to produce something like a $500 SCAR, you first need to create a design that can be made in smaller factories for less cost, the sheet metal stamping and simple carrier and trunnion made from octagonal bar of my monolithic design would allow that, so when its finished the "inexpensive to mass produce" design is there, the second component is not copyrighting or patenting it, let anyone who wants to make and sell them do so while personally not making a dime on it..

i would be willing to make that sacrifice if i thought it would be popular enough because whats important to me is getting better weapons into as many american hands as possible.. and i look ahead and plan for a variety of scenarios, including unlawful bans, so having something someone can build in a garage is a plus.. where current firearms fail in my option is you generally NEED a factory, or thousands and thousands of dollars in equipment to reproduce the components that make up current rifles, this is the case because no firearm manufacturer things outside of their own factories
 
I love the thinking and would like to see your idea come to life. With that said it's totally unnecessary. Most of what you mentioned as reasons are unfounded. The Uppers and lowers on the AR15 wear very well. Most other components wear out long before the receivers do.
I'm not a machinist so I don't see how it's easier or cheaper.
Take a look at the AR180. Maybe you can build something there. I never understood why a good AR180 wasn't put back into production.
 
ive actually modeled an AR-180 upper receiver designed to fit an AR-15 lower receiver and barrel with adapters to allow the use of AR-15 handguards in a way that allows the top handguard to be quickly removed for cleaning the gas system.. in fact if the AR-18 was adopted and became popular over the AR-15, i predict a lot of the same changes in aftermarket would have still occured leaning to almost the same characteristics but with a simpler design.. like this.. the AR-18 gas system on this is a cup at the end of the piston that fits over a stub of gas tube thats sticking out the back of the AR gas block

jOAO7L7.png
 
the AR-18 gas system on this is a cup at the end of the piston that fits over a stub of gas tube thats sticking out the back of the AR gas block
Click to expand...

If it's still using the AR-15 buffer and spring, then it's just another proprietary op rod AR-15 upper.

Also, you need some kind of housing to guide the op rod.
 
justin22885 said:
ive actually modeled an AR-180 upper receiver designed to fit an AR-15 lower receiver and barrel with adapters to allow the use of AR-15 handguards in a way that allows the top handguard to be quickly removed for cleaning the gas system.. in fact if the AR-18 was adopted and became popular over the AR-15, i predict a lot of the same changes in aftermarket would have still occured leaning to almost the same characteristics but with a simpler design.. like this.. the AR-18 gas system on this is a cup at the end of the piston that fits over a stub of gas tube thats sticking out the back of the AR gas block

jOAO7L7.png
Click to expand...
The AR18 hammer is about .150" further back than the AR15. The pivot pin for an AR18 is in a different place. The AR18 upper is about 1" longer than the AR15 upper.

And, the op rod you have runs through the index pin.

If you try and mate an AR18 upper to an AR15 lower you get an ugly abortion...(note the gap between the two.)

2_rifles_vulcan_ar180_ar15_type_rifle_nib_unfired_.2235.56_126800.jpg
 
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