So we all know of the problems with the rdb system, and pistol calibers don't really have enough gas for DI to work.  So I was thinking what about combining the two concepts.  Perhaps it would mitigate the ejector issues with the rdb.

I was thinking about reaching out to Macon Armory about the idea, but what does the hyve think?

I personally don't want anything pistol caliber using a gas port due to fouling except for maybe 40/357/10mm with the higher pressures but not that interested in those calibers myself.

Why don't you see if it runs in a 5.56 gun 1st?  Preferably w/ an adjustable gas block, turn that sucker way down 1st, then open it up bit by bit.

OP.....tell us about your engineering background   ?? ME  perhaps  ??

Or  CNC set-up/operator/ programming or manual machining  experience ??

Or solids works/CAD experience ??

OR maybe SLS/SLA 3D modeling/prototyping ??


If you don't have any experience in any of these areas.....pipe dream thread.




.

 Eugene Stoner never went to college.  The AR lets even Liberal Arts majors slap parts together and see if they work.

Unfortunately, in these times of DEI at U.S. universities, a college degree in engineering can be meaningless.  I've came across people with Electrical Engineering degrees who appeared to think that a transistor was their sister who used to be their brother.

MHO, YMMV, etc.

From wiki.....


"Early life
Stoner was born in Gosport, Indiana, on November 22, 1922. They moved to Long Beach, California where he graduated from a Long Beach Polytechnical High School.
In 1939, after the Depression, there was not enough money for him to attend college so he went to work as a machinist for Vega Aircraft Company, the forerunner of what became Lockheed Airplane Company (now the Lockheed Martin Corporation).

During World War II, he enlisted for Aviation Ordnance in the U.S. Marine Corps and served in the South Pacific and northern China. In the Corps, he had his first experience of working with heavy-caliber automatic weapons as an armorer.
The work experience and combat training served him throughout his weapons designing career.

Engineer
In late 1945 Stoner began working in the machine shop for Whittaker, an aircraft equipment company, and ultimately became a Design Engineer.

In 1954 he came to work as chief engineer for ArmaLite, a division of Fairchild Engine & Airplane Corporation."




So.....through his experiences over 15 years, he learned on the job how to become an engineer.

I'm betting the OP has neither the education, nor the experience to design, and fabricate what he is proposing.


Pipe dream thread.

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How about all of the above?
I can see how this COULD allow for a piston or DI to operate with less gas.
Change up the lug angle so the bolt is closer to lock and won't fully unlock with blowback force alone.
Then tip it over the edge with a little force from the piston/DO, which could be easily tuned.
Not sure of the actual utility of such a system but it would be fairly straightforward to test, after a little machining.

I've got a liberal arts degree, and I designed and built the Lyndon, by using a 5.7 AR upper, a thumbhole stock, and a trigger jig.  Ran 300 rounds before I scrapped it.  The OP can fabricate and test his idea by screwing parts together.

Electro Mechanical Technician certificate from Vo-tech
Retired USAF Redhorse Special Purpose Vehicle Mechanic, small arms instructor/convoy ops
Machine tool technology AAS

I currently work with a Mechanical Engineer building/rebuild/re-engineer/machine the equipment used to process titanium bar into a sellable product.  Bar peelers, 40' long grinding carts on tracks that they drop white hot titanium bars onto two counter rotating shafts with rollers so they can grind while the bars are hot.  Etc, etc.

If its made out of titanium, most likely it was processed on one of our machines.

Yes, i have some cad, solid works, cam programming experience although i don't really do anything progaming wise.

I'm not sure of gas port locations/pressures


I have a lot of ideas, but I have little time to do anything. Having a farm and Foster children take up all of my free time.

And also include the Maxim Defense RDB recoil system plus the Scheel Manufacturing RDB buffer tube system to do the Full Monty.

This is along the lines of what I was thinking.  Possibly the gas port could be in the standard pistol location.  It would just need enough gas to start the bolt rotating.

Need to work out the angle of repose for the bolt/receiver extension along with the surface finish and go from there.  Use an adjustable gas block to fine tune for load/caliber, that way the bolt lug/receiver extension angles would be the same for all calibers

Are you talking about the radial delayed blowback CMMG system?  What if you add gas-delay instead of DI?  

Hadn't thought of that, but it may be possible to use a modified bolt as a piston pushing towards the chamber.  Would have to close off the carrier vent ports

Uh, it already does that.  You'd need a long stroke piston working as a delay.

At this point, I don't understand what you're trying to accomplish, nor how you're proposing to do so.

DI Gas the Carrier moves first unlocking the bolt.

CMMG RDB the Bolt moves first to unlock.

The new CMMG Dissents have the ejector fixed in the upper which is a much better design and more reliable I believe.

I build a DI 9mm and got it to run really well, bolt, carrier and buffer weight 8.2oz. Has virtually no recoil.
However the system is plagued  with other design issues, 1st is commercial 9mm has virtually no gas volume, my gun took +p handloads. The other issue is the short round making the jump over the lug gap and feeding.

What length is the gas system on it?

Are you using a standard strength carbine buffer spring with it?

~2in
I tried shorter too but things get even more complicated with barrel nuts and hand guards.

Lightweight spring for competition, believe it's a TTI. Used a Taccom poly buffer which weighed half oz or something tiny.