Here are my $0.02 worth, and I am no expert so take it with a grain of salt…
First, everything that has been said so far about over gassing is at least partially correct and can/will cause malfunctions. A couple of notes though:
most commercial 10.5" (yes I know you have a 10.3" DD) barrels have a gas port in the .08x range (even Noveske’s is .082) this is not a manufacturing error, this is done because of all the cheap (non-milspec) ammo that is often used by civi shooters.
Crane spec is .070 or .071 (I have read both) and was based on milspec ammo tolerances.
Suppressed (to not be overgassed) somewhere in the neighborhood of .05x is recommended when using milspec loads - this is what gives such value to the Govnah or other adjustable gas blocks that allow for optimum unsuppressed/weak ammo unsuppressed/suppressed settings - however I digress.
If everything was fine the day before (same rifle and ammo, and suppressor used), Occam’s Razor would suggest that you considered the specific magazine you were using. Even with +10% springs, and Magpul followers there could be an issue with the feed lips that would cause these malfunctions.
Lastly, malfunctions aside, I personally use an H2 buffer for enjoyment’s sake (H2 came standard in the Colt 6920 SOCOM that I had cut down to 10.3")…
Hope this helps.
ETA: Or it could be the select fire lower… in which case you should transfer it to me for swift destruction
These shorties will run an H2 and car spring with a GP of .064 with 5.56 ammo unsuppressed pretty easily. I no longer have my DD 10.3 because the GP measured at .082. An adjustable gas block of some sort is the only true way to fix the true cause. While you can try to patch work the rifle to run a little better, DD pretty much ruined a good barrel with that gas port size.
And the numerous times Ive spoke with DD about this issue is addressed as this… We have much less complaints of overgassed 10.3s with .08x spec gas ports then we would with a .070. Way to many folks do not run 5.56 ammo all of the time and do not run suppressors. SO for a commercial MK18 upper, we have much less complaints having the gun running with all ammo types. This was the basic explanation I received back from a few separate emails into DD a while back.
I see why they do it, but to a select few people that run quality ammo, suppressors, etc, its a major pain. I would run an H3 at least. Or Vltor setup. But I found that it still didn’t accomplish what I was after and sold the barrel. Just a lot of time and money…
I recently inquired about the insertable ports and they informed me they were only selling them with the gas block as a kit. Bummer cause I want to keep using my factory pinned block.
DING DING DING!! Now wouldn’t that be nice!!! Buy barrel A if you shoot crap ammo. Buy barrel B if you only shoot 5.56 ammo or plan to suppress your rifle.
Well even if you have a well machined gas port on your rifle and you’re shooting crap ammo. As for mentioned a heavier buffer we will take care of that such as an h6. it will also help to guarantee a reducing factor of squib load or squib round. yes the buffer can help with that at least in an M4 / AR15 style rifle.
Yeah, just make a second SKU for a 0.071 gas port on the same barrel, call it ‘suppressor ready’, and then see which sells. I’m willing to bet anybody in the market for the Mk18S or Mk18HP barrel would be willing to wait through a backlog just to get a barrel for their intended use - to my knowledge the only other complete Mk18 uppers using CHF barrels are in another zip code of price, so that’s an offering I’d consider to be overdue from DD.
FWIW, I’d be running a DD Mk18 upper if this was resolved, I really like my V5 upper because of how well it shoots. Instead, I’m running a different 10.5" barreled upper, because of this specific concern (as it’s a dedicated suppressed upper).
The Daniel Defense mk18 barrels are proper spec and the handrails are as well. But in order to find a true mk18 upper barrel or rail it is a true unicorn. The reason I’m saying that it is proper spec is because that is the civilian equivalent to the mk18 barrel and the mk18 rail. Not a true mk18, if you were to find a true mk18 you would pay upwards just for the barrel toward about 1200 bucks and for the handguard you would pay roughly the same for a true mk18 handguards.
I retract my statement about the handguards those usually run for a true mk18 handguard for five to seven hundred for the black or between seven and nine hundred for the FDE. Sorry my mistake and there is only 42 I believe in existence of the hand guards the barrels or more than likely fewer.
They were talking about the DD MK18 barrels not being spec, which they actually are. They are just civilian spec true military spec are unicorns. Also the beginning of this post was about a DD MK18 lol. So very on topic brother. Have any questions just ask.
Yea pretty sure were only discussing what we can actually buy lol. What’s the difference between the mk18 .mil rail and the two mk18 fde rails I have sitting in front of me?
As for the barrel all were asking for is one with the right dam gas port lol
I agree. The cost of a “true” MK18 rail or barrel is irrelevant to the problems that the OP is experiencing. I’d also like to know how drilling a different gas port diameter pushes the cost of the barrel to $1200. In the interest of not further derailing this thread, I’ll live without an explanation though.
If the OP’s gun is overgassed with .223 spec ammo then running 5.56 pressure ammo will only make the problem worse, regardless of the type of brass used. Brass/ammo cannot be purchased directly from LCAAP. Per the facility management contract, they are allowed to sell excess brass and/or ammunition if requests are made by another manufacture (i.e. Federal, Black Hills, etc.).
I believe the talk of out of spec on the gas port is in comparison to the Crane spec for the Mk18 barrels (which is pretty universally known) not with respect to the manufacturing spec of a civilian barrel. The fact still remains that .082" gas ports are excessive for anything except steel case import ammo. The barrels could be more conservatively ported and still function .223 pressure ammo without issues and would be more likely to run better when suppressed.
I’ll double check and shoot you a pm. I’m sure their the civvie versions since one is a factory complete upper and the other was from Brownells back when they were available.
What in the name of Moses are you on about? To believe a barrel runs $1200 and a handguard runs $700-900 is absolutely insane. I can get you the price of a NSW Crane built Mk18 or Mk12 upper group and I can without a doubt say the prices you quoted came from a crack head smoking some dope sheeeiiit. Think closer to $1200 for the entire upper package w/ bolt and charging handle.
You think you can. You find me a military version mk18 no civilian rail for under 800 I dare you. I can punch all kinds of holes in your arguement. Because 98% of the MK18 barrels and rails out there are all civilian models. Put that in your pipe and smoke it. You’re the Crack smoker, thinking you have more knowledge than someone that lives guns with a brother that is an actual gunsmith. Guy you are a joke. And I’d appreciate if you’d keep your non helping 1/2 cent outta a big boy conversation. Because right now there are only about 45 non civilian model MK18 rails and less non civilian model barrels on market today. WITF do you think the DD MK18 uppers and barrels have so many bs problems!? Because they are garbage civilian models! THAT’S WHY!
