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Thread: Reports of DD SBR barrels being over-gassed?

  1. #51
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    Quote Originally Posted by ASH556 View Post
    Let's not take this to the nth degree either gents. I've got a factory DD MK18. It came with an H buffer and runs 100% suppressed or not with an AAC M4-2000. I've run it full-auto and suppressed as well on a Post-Sample Colt M4 lower. No issues at all.
    Not at all! I'm all for reliability but I'm just looking to have a rifle that isn't over gassed to the point of self destruction, hence the Syrac that I'm looking at. I can spring and buffer the gun down to be tame but I just want it to not eat itself up. I'm actually in favor of a bit of over gassing to promote reliability over ammo and temperature inconsistencies but how much is too much? 0.086 just seemed a little big to me when the NSWC Crane Ppt stated that the "gas ports were opened from 0.062 to 0.070". I'd be a bit less concerned if DD told me they were 0.075-0.078.

    If they really are 0.086, I'll certainly use a Syrac to choke it down a bit but there are a lot of numbers being thrown around; I read a thread on here this am that said DD reps were saying at SHOT that the Mk 18 ports were like 0.077. That would be awesome!
    "An opinion solicited does not equal one freely voiced," Al Swearengen, Deadwood 1877.

  2. #52
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    DD told me the govt stuff was .70, and that the civi MK18 ranged from .77-.80. As stated above, too many people shooting underpowered ammo, then crying about their problems....cause and effect.
    If mine ever gets outta jail, I will choke it down if needed.
    "I would rather be the hammer than the anvil."- Rommel

    Owner: Hangar 18 Custom Coatings

  3. #53
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    It sounds as though people are getting away with a H buffer when running the MK18, correct? Reason I ask is because I'm just waiting on my stamp while I'm assembling my lower. Want to make sure I'm starting with the right buffer.

  4. #54
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    Quote Originally Posted by BravoHotel View Post
    It sounds as though people are getting away with a H buffer when running the MK18, correct? Reason I ask is because I'm just waiting on my stamp while I'm assembling my lower. Want to make sure I'm starting with the right buffer.
    My factory MK18 came with H and runs perfectly.
    Semper Paratus Certified AR15 Armorer

  5. #55
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    Good to know. Thx, Ash. H with a standard mil spec spring I'm hoping.

  6. #56
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    My 11.5" DD will overrun the magazine with a suppressor using an H2 buffer. I had to go all the way to H3 and it still runs on the verge of failure with a silencer. Brass is chewed to shit.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

  7. #57
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    I measured one port that came out to .082. There is no need for the port to be that large. I believe that the Crane MK18's are at .072-.073 and they will run with M193, M855 and similar loads. If suppressed they will run with .223 ammo as well.



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  8. #58
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    I indexed the gas port on my BCM BFH 11.5 barrel when changing the handguard. It was .073 inch. It's always run just fine shooting PMC Bronze with an H2 buffer.

  9. #59
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    Quote Originally Posted by scottryan View Post
    My 11.5" DD will overrun the magazine with a suppressor using an H2 buffer. I had to go all the way to H3 and it still runs on the verge of failure with a silencer. Brass is chewed to shit.
    I'd love to be able to custom order a short Barrel with a port size of my choosing. I'd like to do a dedicated suppressed SBR that didn't require an adjustable gas block... or a different buffer/spring than standard H2.
    "You people have too much time on your hands." - scottryan

  10. #60
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    Quote Originally Posted by scottryan View Post
    My 11.5" DD will overrun the magazine with a suppressor using an H2 buffer. I had to go all the way to H3 and it still runs on the verge of failure with a silencer. Brass is chewed to shit.
    That's interesting. I suppose it might be beneficial for the group if I pulled my upper down and measured the gas port. I will say this, I ran it suppressed on another lower that had a carbine spring and carbine buffer (PSA made, questionable IMHO) and got about 3 or 4 bolt over bases in a 20 round mag. Same lower with an H2 runs fine suppressed or not.

    At the same time, I ran the upper suppressed on a full-auto Colt post sample lower with an "H" buffer and it ran 100%. Ammo is Fed XM193 brown box and Aguila 55gr .223 brass. I guess my thought on it at this time is that I'd rather it cycle a little faster with the "H" and be sure it'll run .223 pressure/dirtier than run an H2 and potentially be closer to the edge.
    Semper Paratus Certified AR15 Armorer

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