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Thread: Why not more DI guns?

  1. #11
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    The Daewoo K1A1 uses a fixed ejector. For those unfamiliar with it, the BCG on the MCX looks very similar but the K1 is DI.

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    Quote Originally Posted by NongShim View Post
    The Daewoo K1A1 uses a fixed ejector. For those unfamiliar with it, the BCG on the MCX looks very similar but the K1 is DI.
    Yes it does. How they manage that in that space I can’t tell from the pictures I could find on line, unless the ejector is spring loaded, kinda like what HK did on the G3.

    H

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    Quote Originally Posted by amd5007 View Post
    For example, discussion of gas port sizes are almost unheard of in discussions of piston operated systems. In a DI gun, gas port size is vital.
    It's vital in every rifle; but in rifles with massive aftermarket support with a wide range of barrel and gas system length options, people occasionally get it wrong. Unsupported platforms with few choices rarely have home barrel swaps, or the conversations that go along with them.

  4. #14
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    Quote Originally Posted by halmbarte View Post
    DI does eliminate the need for an op rod and moves the gas system back to the BCG. It’s not compatible with corrosive ammo (try to get the gas block and inside of the tube clean) for field use and does require a BCG that can be pressurized, eliminating using a fixed ejector, for example.

    DI also wouldn’t work with weapons that need quick barrel changes as you’d have another point for gas to leak out of.

    As far as a DI bullpup goes, the Tavor is about halfway there. Gas is ported back 3~4” from the barrel tap to the long stroke piston head. From there back it’s pretty much AK like, with improvements.

    H

    The Tavor tried to borrow from both systems when it should have just gone with a long stroke piston and a standard short gas block. Then bleed off the excess gas at the block utilizing inertia for the remainder of the cycle, like the AK does.
    Last edited by RetroRevolver77; 03-15-18 at 21:47.

  5. #15
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    Quote Originally Posted by halmbarte View Post
    As far as a DI bullpup goes, the Tavor is about halfway there. Gas is ported back 3~4” from the barrel tap to the long stroke piston head. From there back it’s pretty much AK like, with improvements.
    The Iranian KH-2002 is a DI bullpup. It's basically a bullpup version of an Iranian unlicensed copy of a Red Chinese unlicensed copy of the M16.

    Quote Originally Posted by amd5007 View Post
    Not sure of the history, but Stoner moved away from it.
    Stoner, along with Armalite, sold his patents relating to the AR-10 and AR-15 to Colt. And Stoner went back to DI later in life, as IIRC, he assisted Knight with the initial development of the SR-25 and SR-15/SR-16.
    " Nil desperandum - Never Despair. That is a motto for you and me. All are not dead; and where there is a spark of patriotic fire, we will rekindle it. "
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  6. #16
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    Quote Originally Posted by halmbarte View Post
    Yes it does. How they manage that in that space I can’t tell from the pictures I could find on line, unless the ejector is spring loaded, kinda like what HK did on the G3.

    H
    It is spring loaded, though in form is hardly like the G3. It is a spring loaded blade that sits in a tube behind the magwell. The carrier keeps it compressed, but as the bolt moves rearward during extraction, the ejector moves up and protrudes through a slot in the bolt. The first time you see one of the bolts it’s common to think a lug sheared off. It’s a pretty neat design.

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    Quote Originally Posted by georgeib View Post
    My best guess is that the buffer tube/receiver extension part of the system that DI seems to necessitate is not nearly as popular as the DI part of it. There are more compact ways to make the rifle cycle in other words.
    Daewoo K1.

    Quote Originally Posted by halmbarte View Post
    All the fixed ejector guns I’m familiar with need to have a slot cut into the bolt body and bolt carrier, preventing them from being used as a Stoner type gas cylinder and piston.

    Gas port size is critical for pretty much any gas operated gun. I think the reason you hear about it so much with ARs is because of the popularity of home built guns and the possible combinations of barrel length, gas port locations, and gas port sizes.

    H
    Daewoo K1.
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    Quote Originally Posted by Fjallhrafn View Post
    Stoner, along with Armalite, sold his patents relating to the AR-10 and AR-15 to Colt. And Stoner went back to DI later in life, as IIRC, he assisted Knight with the initial development of the SR-25 and SR-15/SR-16.
    I was actually wondering before I fell asleep last night as to why Stoner went to all pistons after the AR-10 and AR-15. Forgot that he sold his patents but a part of me wonders if he found the piston system to be a better and went back to DI only because he was working at Knight's and the project required it of him.

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    Quote Originally Posted by patriot_man View Post
    I was actually wondering before I fell asleep last night as to why Stoner went to all pistons after the AR-10 and AR-15. Forgot that he sold his patents but a part of me wonders if he found the piston system to be a better and went back to DI only because he was working at Knight's and the project required it of him.
    It seems to me that most of the guns that he worked on after the AR-15 were not necessarily intended to compete with or replace the AR-15 (although ArmaLite did develop the AR-18 from the AR-16 after Stoner left them in part to compete with Colt and their AR-15/M16 FOW). In fact, I believe that Stoner spent the most time and energy post-AR-15 developing the M69W/62/63/63A and its follow-on projects, which saw their greatest success in the role of a light machine gun, rather than as a carbine or rifle (to the point where the only version of the 63 still in production is a dedicated LMG, rather than the super modular one-receiver-nine-weapons concept that Stoner initially devised).

    Jim Sullivan also seems to have enjoyed his greatest success post-AR-15 with another lightweight LMG in the Ultimax 100.
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  10. #20
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    Quote Originally Posted by georgeib View Post
    My best guess is that the buffer tube/receiver extension part of the system that DI seems to necessitate is not nearly as popular as the DI part of it. There are more compact ways to make the rifle cycle in other words.
    Why do you have to have the buffer tube? I think it is the simplest way to do it and the least bulky,(ETA) for a rifle at least with a stock and gives you the higher sight over bore for a long zone of hits with a fast bullet(?). The gas coming back hits/enters the BCG and by the time it starts moving to be off the gas tubes 'nipple', it isn't getting any more energy from that gas- or not very much? You'd still need some kind of spring system, but why not one like the AK on top? Are the speeds and energies all of the wrong magnitudes and screwing with the timing?
    Last edited by FromMyColdDeadHand; 03-21-18 at 16:17.
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