Why no new DI designs?

[Herk]

Let's get this out of the way immediately: I really don't want to start another "piston vs. DI thread here". I am genuinely curious about what I'm going to ask.

Why do no new designs use direct impingement gas systems? The AR15 is obviously successful and has "proven" that the system works so how come newer (i.e.: FN SCAR, Tavor, BREN 805/806, AK12, etc) designs are all piston-operated? If the simple answer is that "pistons are better" then why are piston-operated AR15s not more popular (indeed, why are they so widely panned)?

It just seems odd to me that the AR15 should be so successful without having its gas system being copied even once.

[ABNAK]

Knight's has basically been the only one to "tweak" the DI system, save for LMT and the Enhanced BCG (which I have two of and love 'em BTW).

[mig1nc]

There was the LR-300 and the Armstech gas trap/DI.

Neither seemed very successful.

Sent from my SM-N920V using Tapatalk

[ABNAK]

There was the LR-300 and the Armstech gas trap/DI.

Neither seemed very successful.

Forgot about those.

[Herk]

There was the LR-300 and the Armstech gas trap/DI.

Neither seemed very successful.

Sent from my SM-N920V using Tapatalk

I wasn't aware of either of those. They both look rather AR-esque; it doesn't seem like a huge leap for them to be DI.

I guess what I'm wondering is why there isn't a DI version (or at least conversion) of the SCAR or similar? Wouldn't that work just as well and be lighter and cheaper than a piston?

[Mr. Goodtimes]

Because of the bullshittery that's plagued the AR-15 for 60 years... that DI is inferior to piston and unreliable.


Sent from my iPhone using Tapatalk

[SomeOtherGuy]

Two reasons:

1) The original AR-15 design is a nearly perfect expression of the concepts: not only the DI producing a soft action impulse, but also the recoil in-line with the shoulder stock and the use of newer, high strength-to-weight materials to produce a rifle that, at least in its original form, was much lighter than competitors while still being adequately strong and durable.

2) However, the DI system does have some drawbacks for common military use. Every design choice has pros and cons. DI makes it easier to make an accurate rifle and have a really smooth recoil impulse, which is why you see it in modern designs for precision (KAC SR-25, LMT MWS) and 3-gun gaming use (various). The cleaning disadvantages, although modest, are very well known.

Basically I think that the minor disadvantages of DI, coupled with the nearly perfect execution of the concepts in the AR-15 design, means that a firearm designer can't really improve on the AR-15 with a DI system, but they can use a conventional piston system and claim to have an all-new "superior" design, with any issues of weight, accuracy or complexity being answered with purported reliability and durability benefits. I'm aware of the military M4 testing and won't bother stating an opinion on whether a well executed DI system is inferior to a well executed conventional piston system.

One thing I do notice is that most forces that operate in arctic conditions do not use DI systems. The US and Canada do, of course, but the Scandinavian countries use other designs (Norway - HK416 with piston; Sweden - HK G3 and apparently moving to LWRCi piston-AR; Finland - AK-derived Valmet; Russia - AKM; China and North Korea - AKM and other piston designs; etc.). I suspect that the DI system is more sensitive to outside temperatures than piston-in-block designs, because the operating gas has to go through 6, 8 or 12 inches of highly exposed, heat conductive tubing before it gets to the operating piston.

[556Cliff]

AS-50 is DI.

https://www.youtube.com/watch?v=XCSaWJDZ7oQ

[MegademiC]

Because business is to make money and you have to sell people on something. The biggest complaint about the ar is reliability, and it's a joke. Shitty companies make unreliable ars, then the same companies come out with piston guns and retro fits to fix their problems, meanwhile colt and bcm shooters just shoot.

If you make a new di rifle, you can't claim better action, and how are you going to compete with the egos and market share?

[Bubba FAL]

Because small arms design has pretty much stagnated. Most "new" designs are highly derivative and thus end up being evolutionary rather than revolutionary. Let's face it-nowadays a JM Browning could never afford to compete for a military contract, matter how great his designs.