Dracos gas expansion chamber?

[Coyote Kev]

Expansion chamber, dwell chamber, whatever you want to call it. Dracos barrel owners know what I’m talking about. I get that the idea is to increase lock time but has anyone figured this thing out? Does anyone feel like they have it tuned perfectly? Does anyone feel like it does anything at all? It comes with zero directions and I’ve got different answers on how to adjust it depending on who I talked to at Dracos. I really didn’t need another variable to deal with when trying to handload for a gas gun, but I’m the dumb ass that bought it.

 

[knuckleballz]

The theory is that it increases the volume in the gas tube and acts as a surge dampener. Adjusting the volume size of the chamber has an effect on your unlocking dwell time. Almost like moving the gas block port farther out on the barrel. I had thought of ways to do a similar thing using larger diameter gas tube/chamber. I also have seen where someone used a long tube and bent it so it had 3 turns around the barrel like a spring coil to effectively increase the gas tube volume/dwell time. These methods could be used on a rifle length gas port barrel to adjust gas instead of scrapping it and going to a plus 2 gas port new barrel. I don't have any connection with dracos but these are my own theories.

 

[knuckleballz]

Subwrx300 has a thread going on the next page about his dracos project. Sorry I don't have personal experience yet to add. Also search back.there have been several threads on dracos builds.

 

[knuckleballz]

I have a 6 creedmoor and a 6.5 creedmoor new in the boxes that I will eventually get built so I will be checking back on this thread to see what info is shared.

 

[Coyote Kev]

Subwrx300 has a thread going on the next page about his dracos project. Sorry I don't have personal experience yet to add. Also search back.there have been several threads on dracos builds.

I think I’ve read most of what’s out there. Not much on this particular subject. I’m wondering.....
How do y’all have them adjusted?
Do you feel like it makes any difference (group size, Brass condition, etc)?

 

[SupressYourself]

It definitely makes a difference in group size. With the adjustment screw completely out (like laying on the bench), my 6mm shot the 103 Factorys pretty well, but sprayed my 87gr V-max handload all over. With it the screw flush to the muzzle end of the chamber, it shoots both pretty well, but always with enough flyers that I can't call it "good".

I think I posted this elsewhere, but even with the screw completely out, like 95% of the gas still goes down the tube. I determined that with the gas block off, using my air compressor. Shooting suppressed, I only had to add like 1/4 turn on the adjustable gas key to get it to cycle the same as with the screw in.

Like you said, it's one more variable that I'd rather not have. This barrel / system has been the most consistency inconsistent one I've tried to hand load for. If it always shot ~.7 MOA, I could accept that. But no, it regularly shoots several in damn-near the same hole, but with a flyer mixed in.

 

[Coyote Kev]

So no one has these barrels? Me and a couple other fools are the only ones that got suckered?

I had a thought on having the plug completely out... It should function somewhat like a superlative arms gas block that vents off the extra gas instead of restricting it. It’s just that the adjustment is farther down the line at the gas key.

 

[Triggs75]

I have the 6.5cm barrel and just sent it back to them to look at it. No matter what ammo, factory or reloads, when the barrel heated up the first round out of every mag was about 1 to 2 inches low. Doesn’t make since and couldn’t figure it out so sent it in for them to see.

I only tried a couple of times to adjust the gas chamber and really did not see any difference so I have been shooting with it closed off.

Chad

 

[BLDTYLRY]

What handguard are you using? Do you have sufficient clearance? Had a similar issue with 22Nosler build running a BSF barrel. Shot like crap. What I found was the gas block didn't have much clearance with the bottom of the handguard and loading the bipod and under recoil the gas block would hit the handguard. Swapped out handguard and the issue went away. Also make sure you do not have a rail section (if keymod or mlok) hitting the underside of the barrel.

Just received a Draco 6CM barrel and have not mounted it yet. Will be installing in either a Mega MML or Aero Precision M5E1 upper. Both should have sufficient clearance. Also I read somewhere that an adjustable BCG is recommended if you run suppressed.

 

[Triggs75]

I have it built on the aero M5E1 builder set with their 15” handguard. Clearance is fine and gas block is just on outside of handguard. Nothing hitting the barrel. I thought that too but it’s really just the first round. After that 1st round it groups ok.

I’m in the republic of kalifornia so no suppressor unfortunately

 

[SupressYourself]

I definitely don't have anything touching the barrel, gas block or tube.

Here's mine shooting like complete dog shit with the adjustment screw removed.
The two better, but still sub-par groups in the middle target are the same load with the adjustment screw flush with the end of the block.

 

[Coyote Kev]

I have the 6.5cm barrel and just sent it back to them to look at it. No matter what ammo, factory or reloads, when the barrel heated up the first round out of every mag was about 1 to 2 inches low. Doesn’t make since and couldn’t figure it out so sent it in for them to see.

I only tried a couple of times to adjust the gas chamber and really did not see any difference so I have been shooting with it closed off.

Chad

Mine does the same thing with the first shot except mine is always high. I run suppressed. I've had this happen with my dracos 260 rem on a JP upper. Sent it back and they sent a new barrel. Same problem with second barrel. Thought my receiver was warped. Put it on an aero precision M5E. Same problem. I've tried several different bullets and powder loads. There is definitely enough clearance with both uppers. I also have a dracos 6 creedmoor. It's on a ascend armory upper with SLR handguard. It's definitely a little tight in that handguard but nothing is touching. This rifle seems to do the same thing.

 

[Coyote Kev]

What handguard are you using? Do you have sufficient clearance? Had a similar issue with 22Nosler build running a BSF barrel. Shot like crap. What I found was the gas block didn't have much clearance with the bottom of the handguard and loading the bipod and under recoil the gas block would hit the handguard. Swapped out handguard and the issue went away. Also make sure you do not have a rail section (if keymod or mlok) hitting the underside of the barrel.

Just received a Draco 6CM barrel and have not mounted it yet. Will be installing in either a Mega MML or Aero Precision M5E1 upper. Both should have sufficient clearance. Also I read somewhere that an adjustable BCG is recommended if you run suppressed.

Yes you need an adjustable gas key if running suppressed. I have a rubber city armory, about $40.

Considering barrel whip, how much clearance do you think you need? Is there anything that says for a 22 inch barrel you need X amount of clearance?

 

[Triggs75]

Mine does the same thing with the first shot except mine is always high. I run suppressed. I've had this happen with my dracos 260 rem on a JP upper. Sent it back and they sent a new barrel. Same problem with second barrel. Thought my receiver was warped. Put it on an aero precision M5E. Same problem. I've tried several different bullets and powder loads. There is definitely enough clearance with both uppers. I also have a dracos 6 creedmoor. It's on a ascend armory upper with SLR handguard. It's definitely a little tight in that handguard but nothing is touching. This rifle seems to do the same thing.

Yes they did state would possibly send a new barrel out. I hope if they do I am not getting the results you have gotten. I really want to like this barrel. If Sub MOA accuracy is what I get out of it that would be ok, just cannot have first shot be so far off. We will see

 

[wilsoncs3980]

I just finished my Draco's 6.5 CM build. I'm running a JP Low Mass Carrier with their high pressure bolt. I have not tried to adjust that gas block yet. I'm shooting sub-moa with the cheapest ammo I could find. I'm definitely over gassed. Brass is ejecting at 1 o'clock. I have the JP silent capture sping installed with the standard spring. I may try the heavy spring and see what that does. I will be installing an RCA adjustable gas key as well.

 

[Subwrx300]

Thought I'd add to the conversation. Regarding the adjustment and it's function (or lack thereof), it works but only just barely in it's current form. I found it helped ejection pattern very slightly (from 1oclock to 2oclock) throughout the adjustment range. Personally, I'd suggest running gas screw nearly completely out even protruding slightly (1-2mm) and using red loctite to ensure it doesn't come out/loose. YMMV depending on load.

I spoke with Dracos in April and they confirmed that they aren't thrilled with the design and said they were working on a new gas block design to allow better adjustment of flow/volume (read: making a normal adjustable gas block). No word on whether it's going to be backwards compatible yet. I'm planning to reach out to them to see how their testing has gone and hope to get an update or ETA for release.

Regarding precision/accuracy, I've had better success with 123gr/130gr bullets than I have with 140+. I've gotten the 123 SMK to shoot fairly consistent 1/2 to 3/4 moa multiple 5-shot groups. The only trouble I'm having currently is vertical spread which is either being caused by bullets unseating slightly (search reloading section for thread) or my rear bag technique (photo attached).

Here is a 6-shot group at 1060yds to show you what I mean: 10" vertical and 5.5" wide. (Sorry for upside down picture)

Here is 100yds with flat bag and low cheek pressure vs vertical bag and heavy cheek pressure. Top left is bolt gun for reference; bottom left group is solid bipod load, flat rear bag acting more like a rider bag vs top right group is vertical bag with heavy cheek pressure downward/hard squeeze on rear bag and same bipod load in all three. Notice the center of each group is nearly EXACTLY the same for both groups. Even more evidence of the need for PERFECT (really perfect) hold on bag, cheek weld and shoulder: the top right group was 3 rounds, break hold and reload magazine and send next two rounds.

While I will say it's been frustrating at times, I've really grown to like the Dracos barrel overall. GREAT heat dissipation, easy to clean and very consistent with the right load. The downsides have been mainly issues with torquing muzzle brake properly (too tight and groups went to shit; too loose and brake would loosen mid session), difficult to tune load and dirty as hell to shoot because of the no adjustable gas volume. But if rifle shoots this well for next 2k-3k rounds, it's worth it. I'm currently at ~2400 rounds with no discernable loss of accuracy. Trying to test their claim of lifetime MOA precision! Lol. Feel free to PM of you have any questions.

Note: I'm not affiliated in any way with Dracos; I bought a blem barrel to test out concept and am considering sending a Krieger AR15 barrel to Teludyne for a straight jacket to compare against Dracos.

Happy shooting!

 

[wilsoncs3980]

I spoke with Draco's yesterday about adjusting the gas block. They said they are leaving the factory adjusted correctly for the corresponding cartridge. Mine is a 6.5 Creedmoor. I've only had it out and shot 1 box of ammo thru it to break in the barrel and check function. My brass looks like hell after firing and it's ejecting at 1 o'clock. I'm going to leave the gas block set like it came from the factory. I installed a RCA adjustable gas key last night. I'll be hitting the range Saturday morning to run another box of factory ammo thru it. I have everything I need to start working up some hand loads but right now I'm not too keen on using my expensive Lapua brass in this gun. Hopefully the adjustable gas key fixes the ejection issues and my brass doesn't get beat to shit. FYI, I'm running the JP Low Mass Carrier with their High Pressure Bolt. I have the Silent Capture Spring buffer assembly with a standard spring. If the key doesn't fix the issues I'll switch to a stiffer spring. Also, I'm running the Area 419 Sidewinder Brake without any issues. Very easy to time it and it works great.

 

[Subwrx300]

I spoke with Draco's yesterday about adjusting the gas block. They said they are leaving the factory adjusted correctly for the corresponding cartridge. Mine is a 6.5 Creedmoor. I've only had it out and shot 1 box of ammo thru it to break in the barrel and check function. My brass looks like hell after firing and it's ejecting at 1 o'clock. I'm going to leave the gas block set like it came from the factory. I installed a RCA adjustable gas key last night. I'll be hitting the range Saturday morning to run another box of factory ammo thru it. I have everything I need to start working up some hand loads but right now I'm not too keen on using my expensive Lapua brass in this gun. Hopefully the adjustable gas key fixes the ejection issues and my brass doesn't get beat to shit. FYI, I'm running the JP Low Mass Carrier with their High Pressure Bolt. I have the Silent Capture Spring buffer assembly with a standard spring. If the key doesn't fix the issues I'll switch to a stiffer spring. Also, I'm running the Area 419 Sidewinder Brake without any issues. Very easy to time it and it works great.


View attachment 6914808


View attachment 6914809

I'm not sure that the "factory adjustment" means anything. Over gassed is over gassed and the dwell time adjustment even maxed out on mine made very little difference. Hopefully the adjustable gas key helps your ejection pattern but the edges of their extension are wicked sharp. I'm only just now getting normal-ish looking brass after 2000+ rounds. Still have knicks and cuts but less than when it was new.

Personally, I'd back it all the way out. I'm going to try removing screw entirely just to see what happens. 99% sure it will function just like normal. With a suppressor, it will likely be the only way to keep the pressure reasonable. Unfortunately, I don't have the option of running an adjustable key due to my BCG but that's besides the point.

Great looking build by the way.

 

[wilsoncs3980]

Here is what my brass looks like. Every one has these cuts / scratches. The edges on my extension are like razor blades as well. I did notice my JP Bolt has an Oring on the extractor spring. I’m going to remove the oring and adjust the gas key tomorrow with some factory ammo and see how it runs. Anyone else ever have problems like this with their brass?

 

[Subwrx300]

Here is what my brass looks like. Every one has these cuts / scratches. The edges on my extension are like razor blades as well. I did notice my JP Bolt has an Oring on the extractor spring. I’m going to remove the oring and adjust the gas key tomorrow with some factory ammo and see how it runs. Anyone else ever have problems like this with their brass?

View attachment 6915208

Had the exact same problem with my Dracos for most of the first 2000 rounds. It started to go away with a heavier buffer, flatwire spring and, frankly, wearing in of the barrel extension. If you are careful, you can use an Emory paper strip or super fine file/hone and stone the edges/tips of the barrel extension at the 2 through 4 o'clock position. That should help quite a bit but go VERY VERY carefully into that process.

Those marks are pretty common for new barrels with too much gas/velocity at extraction. I have the same on three different new barrels in AR platforms. The ones with adjustable gas blocks allow me to minimize scratching but it's still there slightly.

Only fixes are adjustable gas block (not possible on this rifle yet), maybe an adjustable gas key (haven't tried one) and/or rounding the corners of the extension (either with file or with use will take a lot of rounds.)

 

[knuckleballz]

After looking at the gas tube on a dracos barrel, the expansion chamber port hole can be drilled and tapped. You would then have an adjustable gas block. The existing adjuster for chamber could be used to lock the new adjuster in place. This would eliminate the expansion chamber. Dracos could easily make their gas block adjustable to fit existing dracos barrels. I have to many other hunting projects that require my attention as the season approaches or I would work on this. I have a 6 and 6.5 creedmoor dracos barrel.

 

[knuckleballz]

I was going to check with dracos and see if they would sell their gas tube assembly separately.

 

[knuckleballz]

The expansion chamber port hole is #36(.100) which is perfect to run a 6 32 tap. I would use a stainless cap screw and anti size on the threads.

 

[knuckleballz]

6 32 screw length ideally would be between 3/4 inch, and 1inch in total length.

 

[Subwrx300]

I was going to check with dracos and see if they would sell their gas tube assembly separately.

I actually called them about this two months ago to purchase a spare block. They said they couldn't because " they are machined 1:1 with each barrel" for tolerances. Not sure I buy that line but regardless I couldn't get a spare. I wanted to try doing the same thing but don't want risk ruining the block and be stuck with a broken/malfunctioning $900 barrel.

Very good to know in the size of the port; I may try this in a month or two if I get frisky.

 

[wilsoncs3980]

I installed an adjustable gas key yesterday and shot a couple boxes of ammo thru it today. I used the RCA key. Very easy installation. I have to say it works great. Very easy to set-up. I shot a box of 129 gr Hornady SuperPerpormance SST. Gun didn’t like it much. Still shot around 1MOA though. I was shooting 5 shot groups at 100 yds. The gun and I both got better with each group. My round count is only at 60 after today. Just a heads up. Don’t use hot loads like Super Performance for setting up the gas key. I had to open it up a bit more so the bolt would lock open on empty mag with Hornady 143 ELD-X Precision Hunter Ammo. I had a severe over gassed gun that was throwing brass 10 ft at 1 o’clock before switching the key. It’s now right at 4 o’clock in a nice neat pile. The 143’s shot better. Smallest group was .416”. I was shooting off a bipod only. No rear bag. Left it at home. Also using a cheap scope. I think the gun will get better after a few more rounds down the pipe and some hand loads.

 

[SupressYourself]

Personally, I'd back it all the way out. I'm going to try removing screw entirely just to see what happens. 99% sure it will function just like normal.

I've done this. It works fine. I just had to give it a hair more gas at the adjustable gas key for reliable ejection. At first I thought it shot better like that, but then it was worse, so I put it back in and left it flush with the end of the block.

 

[Mj30wilson900]

It definitely makes a difference in group size. With the adjustment screw completely out (like laying on the bench), my 6mm shot the 103 Factorys pretty well, but sprayed my 87gr V-max handload all over. With it the screw flush to the muzzle end of the chamber, it shoots both pretty well, but always with enough flyers that I can't call it "good".

I think I posted this elsewhere, but even with the screw completely out, like 95% of the gas still goes down the tube. I determined that with the gas block off, using my air compressor. Shooting suppressed, I only had to add like 1/4 turn on the adjustable gas key to get it to cycle the same as with the screw in.

Like you said, it's one more variable that I'd rather not have. This barrel / system has been the most consistency inconsistent one I've tried to hand load for. If it always shot ~.7 MOA, I could accept that. But no, it regularly shoots several in damn-near the same hole, but with a flyer mixed in.

Isn’t that the selling point of the barrel that it should not have fliers due to consistent temperature? Either way if I was just shooting small groups I wouldn’t buy this animal. But I am a technology freak and wether it works or not I like to test and play around with it. Worst case scenario. I rebarrel. The craftsmanship that went into this gun machining wise is really intricate. Yes it could loose a lb or two and it would truly be a head turner. Taking a lesson from roam and doing a magnesium lower would up the ante with this gun. Really wish they included a manual or pdf file. The company states the only rifle they do that with is the Petra.

 

[1moaoff]

Not alot of weight in the lower really by percent overall from what I remember

 

[AMGtuned]

Isn’t that the selling point of the barrel that it should not have fliers due to consistent temperature? Either way if I was just shooting small groups I wouldn’t buy this animal. But I am a technology freak and wether it works or not I like to test and play around with it. Worst case scenario. I rebarrel. The craftsmanship that went into this gun machining wise is really intricate. Yes it could loose a lb or two and it would truly be a head turner. Taking a lesson from roam and doing a magnesium lower would up the ante with this gun. Really wish they included a manual or pdf file. The company states the only rifle they do that with is the Petra.

Look into the Teludyne Tech StraightJacket system and Teludyne Custom Shop. You would be happier with your results.
http://www.thenewrifleman.com/descent-into-madness-intro-to-teludyne-tech-and-the-straight-jacket/

StraightJacket Barrel System from Teludyne Tech Ind | Soldier Systems Daily

The StraightJacket Barrel System from Teludyne Tech Ind is a thermal management technology that conducts heat away from the barrel and increases barrel rigi ...

soldiersystems.net

Teludyne StraightJacket Proof from H.P. White

Finally nobody has to believe GunsAmerica that the Teludyne StraightJacket is nothing short of a miracle for rifle accuracy over sustained fire. If you read our original article, Ultimate Accuracy Makeover, but didn't send your gun to Teludyne, you may want to beat the crowds now because they...

www.gunsamerica.com

 

[Triggs75]

Look into the Teludyne Tech StraightJacket system and Teludyne Custom Shop. You would be happier with your results.
http://www.thenewrifleman.com/descent-into-madness-intro-to-teludyne-tech-and-the-straight-jacket/

StraightJacket Barrel System from Teludyne Tech Ind | Soldier Systems Daily

The StraightJacket Barrel System from Teludyne Tech Ind is a thermal management technology that conducts heat away from the barrel and increases barrel rigi ...

soldiersystems.net

Teludyne StraightJacket Proof from H.P. White

Finally nobody has to believe GunsAmerica that the Teludyne StraightJacket is nothing short of a miracle for rifle accuracy over sustained fire. If you read our original article, Ultimate Accuracy Makeover, but didn't send your gun to Teludyne, you may want to beat the crowds now because they...

www.gunsamerica.com

Aren’t they part of Falkor/Dracos now?

 

[AMGtuned]

@Triggs75 they are not. Teludyne Tech is the company that created the StraightJacket barrel system. Falkor had their own plans for their semi rifles, and bought a patent agreement. The make-up, and theory remains the same; but falkor wanted a rifle barrel they could sell to anyone, right off the shelf. So they changed some things. First was diameter, so you could slip a barrel nut over the barrel. Then they had to modify the gas system to accommodate the barrel nut. Both of these changes to the original product are enough to make me not buy one.

I used to think Falkor was neat. Nice ambi receiver sets, the Petra, etc. The jersey shore type IG, and some false claims have been enough to keep me away. Teludyne Tech will have a customer from me, and anyone I know, for life. Outstanding customer service, and an amazing product.

 

[Mj30wilson900]

@Triggs75 they are not. Teludyne Tech is the company that created the StraightJacket barrel system. Falkor had their own plans for their semi rifles, and bought a patent agreement. The make-up, and theory remains the same; but falkor wanted a rifle barrel they could sell to anyone, right off the shelf. So they changed some things. First was diameter, so you could slip a barrel nut over the barrel. Then they had to modify the gas system to accommodate the barrel nut. Both of these changes to the original product are enough to make me not buy one.

I used to think Falkor was neat. Nice ambi receiver sets, the Petra, etc. The jersey shore type IG, and some false claims have been enough to keep me away. Teludyne Tech will have a customer from me, and anyone I know, for life. Outstanding customer service, and an amazing product.

Jersey shore type ig hasn’t really hurt noveske. Quality speaks volumes everything else can go away. I don’t see boots obermeyer promoting his product like that. Because he don’t have to. When the young crowd gets a clue they will buy quality.

 

[Triggs75]

Ok I guess when I look up Teludyne Tech it ends up at falkor even on their Facebook.
Do you have a link for them?

 

[AMGtuned]

Ok I guess when I look up Teludyne Tech it ends up at falkor even on their Facebook.
Do you have a link for them?

https://m.facebook.com/TeludyneTech

Thats what I can do. I used the Custom Shop, which Is under an overhaul by way of the owner. Back up and running soon I'm told. If you're interested in the system, send a PM