It appears to me that these drawings were done in SolidWorks. If that is the case would you consider making an E-drawing file of the assembly available for closer review of the design?
ETA: Or maybe post a cross section view. Through the vertical axis down the centerline of the bore.
EDUB
If we decide to release it open source we will but for now I would rather just discuss the concept itself of doing an open source upper. I didn’t mean for this to become a design review, as part of being open source means that the design could be modified and improved by anyone with a good idea and some design skill.
Mistwolf,
Regardless of what one or another gunsmith says, a part has to be kept to spec, whether in an AR or otherwise. An out of spec AR is useless just like any other design. Regarding the inner collar, it was introduced in 1895 and was used, according to Stuart Otteson in his book “The Bolt Action,” on the M98. He discusses this on both pages 7 and 10, describing in more detail the benefits of such a setup on page 10. Maybe he is wrong, I’ve not worked on any Mausers, but his book is considered a pretty definitive source. Regardless of if it’s used on the 98 or not, it’s used to great success on several designs and I think it is a great addition as a feature. The thing about open source is that you could take the design, tweak it to us AR barrel extensions, and advocate your version. Incidentally I am aware of many of the laws of physics but I am more concerned with actual performance than theoretical slight disturbances in moments of inertia. Again, I have experienced, nor have I ever heard of anyone noticing an increase of muzzle rise because the cg of the bolt carrier was slightly above the bore. I would like to be enlightened, however, if this is the case because I consider myself a student of firearms design.
Someotherguy, again good points you bring up. I hadn’t thought of other piston companies just being able to adopt the design and sell it over their own design or alongside their own design. It would only make sense. Then those companies could work on enhancements which would give their version an advantage, be it coatings or otherwise. Although I believe you are correct at that point they could perhaps file a design patent on their version. Perhaps this is what a Creative Commons License is used for? (Mentioned by the owner of Local Motors).
The more I think about it, the more I like their (Local Motors) approach to some degree. Have one guy or entity have control of the project, proposed changes go through him/it and are finalized by voting by members. Data files are issued out with the agreement not to patent any changes. This guy/entity would need compensation, but there wouldn’t be a need to have a full business built around it with little factories like Local Motors. To help fund the startup, maybe have a 10 dollar buy in to be a voting member and acess the data package, or put it on that funding website that was mentioned (same post as Local Motors link)?
Perhaps I’m misunderstanding what is being defined as the collar
Let me preface the comments below saying I’m not familiar with the Creative Commons License and I will need to look it up. I’m also only marginally familiar with the GNU license. I’m a lawyer but not an IP lawyer and, of course, you will need to eventually engage a lawyer who is an IP specialist, if you haven’t already done so. Maybe such a person could step forward as part of the project (vs. the usual hourly rates).
Thinking about this overnight, I think it might make sense if you don’t publish the entire TDP free of charge, but instead make the TDP available to parties who enter into a license agreement with you that stipulates various terms, including restrictions on how they can market this (mostly that there are penalties if they market something as complying with parts A, B, C of your TDP when they know it actually doesn’t) but perhaps as importantly, restrictions on what they can patent OR requirements that they allow the TDP creator/holder entity to obtain such patents itself, to become part of the “open source” arrangement, OR allowing them to patent any improvements they want, but being obligated to provide a free license of those improvements to other TDP licensees if the improvement is of a type that’s deemed essential or integral to the design.
Some companies (think publicly traded defense contractors) probably wouldn’t agree to that, and that’s fine. They don’t play. I expect a decent number of privately held companies would see the wisdom and benefit to all from this approach.
I hope I’m not boring people posting all this IP-licensing stuff in the open thread, but I think it’s very relevant and will affect the success of this effort. Anything you think should be discussed privately just send me a PM.
Repeating that I’m not an IP lawyer, I believe there are separate categories of patents: design and functional. Functional patents are what we normally think of as patents and should represent true inventions or innovation. Design patents, as I understand them, are simply a specific shape/dimension or other implementation of a concept, and represent only a protection of that exact implementation, not the basic functional concept. I believe Ruger has a design patent on their scope ring half-moon cuts, for example, while most other firearm patents would be functional patents.
Where I’m going with this is that I don’t think the TDP should care much about specific outer shapes (like the quadrail cross-section) or cosmetic differences in this design, but should care greatly about functional improvements or needs.
On a different note, if this becomes a going project I would like to support it, but I’m not a manufacturer and don’t own a machine shop. Perhaps this could be organized as some sort of nonprofit corporation (it won’t be a charitable 501(c)(3) of course) which people could join, and by joining they might get minor benefits such as being first in line to buy products based on this design, hopefully at a discount, from companies that are early manufacturers. (I’m well aware that buying early likely means I’ll be getting a beta version at a higher cost than later final versions - but it might be fun to buy one anyway.) Just another thought for discussion.
I’m particularly interested in these features:
-easily removable barrels
-a standardized improved bolt and carrier design
-not needing the buffer tube buffer/spring setup (if I understand correctly)
On that last point, I think it fully makes sense to initially do this as just an upper that’s compatible with standard AR15 lowers - but after that upper design is to market and debugged, then it might make sense to do a new lower design with features such as an ambi safety, modified bolt catch, and most of all a design to handle a folding stock with no need for accommodating the AR15 buffer tube arrangement.
I am not a design engineer, but a computer security guy with some program management experience. One thing I have figured out over the years is that to implement a project improvement program, someone has to define what you want to improve and what will be considered acceptable.
So let me ask some questions:
The specs for the #1 really do not make a great rifle for #2.
i.e.
For #1, quick mag changes are essential as well and the ability to do multiple mag dumps. For #2, quick mag changes are a nice to have. Multiple mag dumps happen less and less as the price of ammunition goes up.
For #2, the ability to take large game like deer with JSP bullets would be a great selling point. For #1, it is a FMJ world and the bullets need to frag.
For #2, compatible mags to an already existing system is a great selling point. Even if the internals need to be changed out. For #1, I consider it a liability if the current mags don’t work perfectly.
Weight matters to both, but the military is trending to going heavy, where I am trying to go less and less.
Length can matter to both, but the military can do things that civilians can not or can not without extra cost and paperwork.
For #1, they want one cartridge and that is that. For #2, a switch cartridge rifle configuration is a great selling point.
Massound,
If you need any conceptual 3D parts let me know. I’m sure we can work something out if having part in hand is helpful in the design. I have printed a few parts in the firearms area. I can use SolidWorks files and the material is an ABS/PC blend. I also have software and program for 5 axis CNC’s if help is needed there.
There are two key features I would like to point out.
Thumb Screw Pressure Adjustor for different barrel length or suppressor setup. The thumb screw simply increase or decrease the internal blow back gas pressure for the appropriate operation.
Composite Piston Dish pushes the bolt carrier group for shell extraction and feeds magazine bullet to the chamber. It completes one operation cycle without the need of buffer tube. This feature helps reduce weight and allows the attachment of folding stock.
All key Piston + push arms components are made with heat resistance light weight composite materials.
The counter balance and the pressure relief valve are the keys to balance the entire cycle of operations.
Just update the diagram with v2 design.
Guys I am all for free and open design discussion - I have been involved in many
The one rule that I have always kept uppermost in my mind is ‘are we making this different to make it better or are we making it different just to be different’
Ask yourself that on a regular basis as you move forward- this applies to everyone and helps keep your efforts ‘in the hood’
Be safe
LAV
LAV, that’s very true and something we need to keep in mind. When I laid out the specs for the design, I tried to include the best features of all the existing designs. The AK and AR are obvious contributors of course. But there is a limit on how much “awesomeness” you can pack into a design, and a lot of it is subjective. For example, I consider fixed ejection preferable, and don’t need to be able to remove the barrel in 30 seconds. We have all seen direct impingement rule the day, then be considered chopped liver, then to come back in favor to some degree after some bad side effects of piston AR’s surfaced. Do you feel that there is room for improvement in rifle design today? I’ve read somewhere that you were involved with the HK 416 (or was it the HK pistol?), anyhow, in talking to some HK engineers at SHOT one year, I got the sense that even they felt constrained by the “box” of the AR platform.
CPTM4, It is good to see some out of the box thinking. I see some issues which you may have already considered, namely large reciever height to contain a circular cam capable of moving the BCG several inches. Without a recoil spring, you may experience some problems with bolt bounce causing the BCG to come out of battery. There are ways of working around those I’m sure.
Blowby, excellent! If this project moves forward, you will be an invaluable asset. The actual upper receiver and the forendn, both extruded pieces, would benefit greatly from prototyping rather than just moving to tooling. Thank you for your offer! Also that 5 axis capability might come in handy for cam paths and such.
RWblue, this is definitely not oriented toward the military. I saw first hand what it was like with the ACR and those solicitations. Also, since this will fit on an AR lower, the calibers are limited to AR calibers, 5.56, 300Whisper/BLK, etc. I personally of the camp that I don’t consider switching calibers to be that useful. I thought it was the greatest thing for quite some time. I have a .40 and .357 Sig barrel for my pistol, I bought a bolt gun that was switch barrel and designed another one. What I found was it wasn’t useful to me because I just never switched them around. A 5.56 upper and a 6.8 upper is a little different, since they all have their own dedicated optic, bolt, etc. Other people may have vastly different experience. In any case, on this upper design, you can swap barrels with an allen wrench. Does that clarify the design intent a bit?
Someotherguy, again good points. I consider the IP stuff fully relevant. We’ve dealt with it our other products, it’s just part of the game. I wish it wasn’t quite so complex though.
I would want to impose as few restrictions on the design as possible if it was open source (in reference to your levels of adherence to the TDP) but at the same time, a design freeze has to be implemented at some point for production. Maybe this frozen TDP is the one to release, but with the intent that other manufacturers would be supply aftermarket parts (i.e. market a chrome lined barrel instead of the stock nitrided barrel) and that any deviation from the TDP would have to be published. Manufacturers could make the full upper if they wanted but again would have to agree to publish any deviations from the frozen TDP. Naturally, there would be a Gen 2, 3, etc. and any improvements made to the TDP by the aftermarket could be incorporated into the new “official” TDP at will. I think you are on the right track here. My question then is, have we de-incentivized improvements to the TDP when an aftermarket company will see their own little enhancement included in the full distribution, version 2.0, TDP?
Thanks for the thoughts guys! To reiterate, a design review (the fun part), would be the next major step. But before that, we still need to work out some details and find someone who is capable of ramrodding the project. A designer/engineer familiar with low volume production could potentially earn some beer money or even a full salary.
Justin
If I understood Larry message correctly, I think we ought to ask ourselves the following questions.
Are we bringing any unique features to do the table? Are we creating a better and more efficient design?
*OR *
Are we just re-engineering wheels when they are already plenty of better proven designs in the market?
I think this project could be a wild success even without any unique features. It’s fine if it simply reorganizes a variety of existing ideas in a particularly good implementation. That’s how the overwhelming majority of gun designs since 1950 or so have come about.
Value of this project? Primarily in creating a single concept of a modern small to medium caliber semiauto rifle, without being subject to the severe design restrictions of all proprietary designs. Nearly all existing cloned/copied designs originated from military designs that saw production in multiple countries and by numerous companies. That is becoming a much rarer thing today, resulting in a multitude of proprietary designs, many of which are individually good, but limit potential aftermarket support and enhancement. This project could get around that.
The AR15 is certainly well proven and works great, but that can also be said about the M14, FAL, 1911, etc… just because a design is solid doesn’t mean it needs to be the end-all, be-all. Especially with a project like this focused on the civilian market. You could run a military with no small arms designed after 1960 and not be significantly disadvantaged, but that doesn’t mean that innovation is a bad thing.
Going to specifics on this concept:
-DI works fine, but pistons do also, and many people prefer them
-Quick-change barrels may not be needed, but can be useful and have little drawback
-A folding stock isn’t essential, but it can be really nice to have
etc. etc.
The other value of this project, which is derivative of the first, is that this could potentially result in a significantly lower cost to the end-user when compared to proprietary designs, because the manufacturers of this design have little to no research and development cost, and cannot product any features of the design that are part of the open source TDP. That means competition based on manufacturing and distribution costs only, not claims of superior design of engineering (some of which today is simply successful exploitation of fanboyism). In other words, prices and competition like we see for AR15 clones, and unlike what we see for the SCAR, ACR, XCR, etc.
Assuming we could do a better job than proprietary designs, what criterias would you consider a better or more efficient design/implementations? Are we creating another AR design, or a completely new tactical rifle design with unique caliber?
I’m going to be following this. When I have something to contribute, I will.
This is a great idea, and I’d love to see it work.
So this is a nice topic and all and since I’ve been wondering something for a while now I’m just going to post it here:
Instead of dropping an AK piston into an AR, why not modify the direct impingement system? Change where the gas is vented. Shorten the gas tube, add a tiny “piston” in the upper between it and the gas key, and blow the gas out the side of the upper or something? Actually design something instead of McGuyvering an AK piston system into an AR.
P.S: Why can’t I post in General Discussion? 
Instead of design an complete rifle, which is a very ambitious project in my humble opinion, why not just focus on one rifle key component (i.e. BCG, handguard, stock, stripped receiver, iron sight, magazine…etc). It would takes less time to complete and easier to see the result.
Designing one component at a time, would be a good test to see if we have what it takes to do a better job than proprietary designs. The experience and knowledge we gained from designing one component at a time, would also help pave the way for a future complete rifle design.
Anyone want to pick the first component?
I nominate the gas key to gas tube relationship as noted above. 
It currently appears that a professional firearms designer with excellent credentials has already made a design for a complete upper (not a complete rifle). I am far more inclined to follow on his proposed design, with potential for changes as useful, than to take the different approach you suggest.
I would also suggest that if you want to pursue a sort of open-source firearm component design team, that would be a good topic for a new thread.