Specifically, what barrel brand / twist rate and length are you using and what gas length? I know they can be troublesome. I just want to know about the ones that work with a piston. I think I want to build  a 300 blackout , possibly with a short barrel for use with a silencer and subsonic ammo. It will have to lock open properly using factory subsonic and without the silencer.

I too am curious.  since its introduction I keep hearing about companies trying it and failing to get it to work with subs.  I have heard of success but I have never seen  it backed up independently.

Syrac has a video showing their new piston system working on a Noveske SBR, full auto, suppressed but that is about the extent that I have seen in piston driven 300 blackout.

I know LWRC & PWS both use DI in 300 blackout which is concerning.

I even question the Syrac system's functionality in 300 blackout.  I have no doubt that it will run suppressed in full auto like in the video but how about in semi auto, not suppressed with subs?  I posted this question on the lengthy thread that linked the video and have not gotten a response from anyone.

I want to try one of the Syrac piston systems but they are sold out everywhere, Syrac is delivering slow and have been nonresponsive to questions on their product introduction thread.

Someone who is lucky enough to get their hands on one will just have to test it out and report back to us.

FYI, anything in 300 blackout will have to use pistol length gas.  There would be no prayer for a piston system in any other length in this caliber.

PWS uses DI in their blackouts????

Negative.

My mistake, I see now that PWS is making a piston 300.  The review I read on TheTruthAboutGuns was not favorable though.  They said that their tester was ammo picky.

As an experiment, I thought I would move my Ares Defense piston kit on to a 300 BLK barrel to see if it would work.

Barrel was a Wilson Combat 16", carbine gas system in stainless steel.  The barrel's gas port diameter was 0.106".  

It didn't cycle properly even with "hot" super loads.  Short stroked with some failures to eject and the bolt would not lock back on a empty magazine.  Tried using a Wolff reduced power buffer spring.  Same issues.

I'm sure that the orifices in the piston spigot could have been opened up to achieve proper operationbut I did not want to mess with a kit that performed perfectly on a .223 carbine.

Lesson learned.

If you contact the manufacturers of pistons they will give you the low down on using them with 300BO.  Here's the things you need to know:

1. You have to use a pistol-length gas system, even with longer barrels that would typically be carbine or longer.  The efficiency that the powder burns with in the blackout means you have to tap the gas early to get the piston moving.

2. You have to use lightened parts.  Again, because of the limited and efficient powder burn the parts need to be able to move as easily as possible.  This means lightened carriers and standard to lighter buffers, and possible even lower-power buffer springs.

3. Adjustable gas blocks help find the balance between components, ammo power, and recoil.

So with all that said and extensive discussions with Aro (good guy btw) at Adams Arms I built an XLP piston-powered pistol (say that fast a few times... )  It works flawlessly, shoots soft, and is a real joy to shoot.  It has taken pigs to about 200yds and at some point will be taking whitetails as well.  With the 10.5" barrel and FH in place (the QD mount for a YHM can once my stamp comes in) the OAL is a mere 26" with weight in the 6.5lbs range.  It serves as my primary HD piece and goes on trips with me as my truck gun.  Love the thing.  

FYI it's using the Adams XLP with their lightened carrier.  Barrel is a Bergara melonited unit, but I may be changing that out for something else.  It's a fine piece but their chamber is on the minimal side so that purchased reloads with standard dies have issue with chambering.  I've found when I reload by running them through a small-base 5.56 die this eliminated the problem, but really works the brass.  With 5.56 brass I don't care, but the .300 is a bit more labor-intensive to make or more expensive to buy, so I'd prefer that it live a bit longer.



So yes, a reliable gun can be built to run the 300BO, just have to play by the rules of physics.

What weight buffer, standard? What spring are you using?      What twist rate is your barrel? Now I hope Syrac ordnance comes out with an option with a light carrier, I do have a light AA carrier.      Thanks for your response. Hopefully I will see more responses like yours.
                                                             

I used a 8" aero precision barrel with a 1:7 twist. The barrel has a pistol length gas system. The piston used is a syrac ordance pistol length. I used a JP silent spring setup and did not change anything from the original for the 556.  It will run on subs and supers with no issues. So far 600 plus rounds with only a few problems but that was me removing and cleaning the piston after shooting and not installing it properly. One thing I have noticed is that 208 max subsonic loads do not lock back all the way however the 220 gr matchking loads do lock back fully. I think its my powder weights on the 208's  but I have to experiment a little to find out. The subs run a little slower out the 8" barrels than a 16"  so you could push up the powder weight a little when reloading them. The supers are 125 gr and 147 m80 surplus bullet loads and all of those run fine. Other than that no real trouble. Its fun as hell to shoot. I will have all the parts for next SBR in 300 blackout piston build this week and I plan on documenting the build so keep an eye out for the post.

The YHM on the Bottom is my piston 300 blackout build the AE is an DI 300 blackout. Guess which one is dirty as hell when shooting supressed


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The Syrac system is the one that I am wanting to put on my 10.5" 300blk build.  I just need to find one in stock.

I order one from Brownell then cancelled (they have been on pre-order for months) and then order one directly from Syrac Ordance. That was a few weeks back. It will get here today This one is for my new 300 build
The reason I said all that is because you may want to order it from Syrac and wait for the back order  I had to wait about a month or so for the one in the YHM build pictured above.  I tried to buy two when they called but could not because of the back orders. Its a great piston system imo

You convinced me.  I just ordered one from Syrac.

I have one of their adjustable lo pro gas blocks on my 16" Noveske 223 and I like it.

I was going to hold out awhile since I am waiting on my tax stamp to build my 300 but I don't want this one thing to hold me up when the stamp finally comes in.

I had hoped that Syrac would make a NIBX light weight carrier with a set screw gas block but if this one works out well I will probably order more in the future.

I have built several 300blk pistols and SBRs with the Adams Arms XLP kit and low mass carriers. sometimes the really short barrels wont lock back on subs without a suppressor. but in general they have worked great.

I'm considering building a 338 Spectre to shoot exclusively suppressed.  Would this likely hold true for that caliber as well?

Yes standard buffer...

Not familiar with the 338 enough to have an opinion.  Research it and determine where a complete powder burn occurs in barrel inches.  It's about 9" for the blackout, and about 18" in 5.56.  You'll want the gas port within that range.  I would expect a high efficiency like the blackout, but with a larger initial powder charge the light carrier and other precautions for the sake of operation may not be necessary.  Until someone actually tries though...

I have been running one of the new Ruger SR-556TD rifles in 300BLK.  This is the new "take down" system with the quick change barrel.

So far I don't have a bunch of rounds through it (working on changing that!) but the gun is running fine.  It runs subsonic without my can attached on setting #2 and supersonic without the can attached on setting #1.  And, of course, it runs subs suppressed on the #1 gas setting as well.

What barrel length?  Is there a factory piston pistol / SBR barrel available?

So far the only thing Ruger's offering is a 16" barrel.  

I think a 10-12" barreled pistol format would be awesome!

Just heard about this new offering from Ruger.  I'm very interested in it, and will be waiting to hear about your experiences.  Thanks.

I have right at 100 rounds fired now.  That's pretty much a 50/50 mix of subs and supers.

From what little shooting I've done, I believe the gas ports in the regulator were designed around subsonic ammo.  I say this because the gun seems fairly overgassed when run suppressed with supers.  I haven't had any malfunctions or anything running supers suppressed (gas on #1 setting) but the gun seems to cycle pretty hard.  I might play with a heavier buffer just to see what that does.  Anyway, it might have been interesting if Ruger had taken the 3rd gas settings and made that hole smaller rather than larger and reserved that last setting for supers/suppressed.

Overall, I am happy with the rifle and I'm pleased that Ruger has added the QD barrel feature and added the 2-stage trigger and Magpul furniture without increasing the cost of the firearm.


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Audible Prime posted:

"I had hoped that Syrac would make a NIBX light weight carrier with a set screw gas block but if this one works out well I will probably order more in the future."

My response:
You seem like a fairly savvy builder. I am curious. Why on earth would your want a set screw gas block over the vastly superior method of the clamp on version? I prefer clamp on gas blocks to any other method including taper pins. I can rotate any set screw version that does not have deeply milled dimples (for EVERY set screw) done in a machine shop (extra cost, time and chance that your machinist will botch your barrel)

A clamp on using the prescribed 32 inch lbs of torque on the three robust machine screws will make the gas block virtually an integral  part of the barrel.  Proper dimpling of the barrel (only method that will correctly hold a set screw version) or milling out for taper pins both are partially destructive to the barrel and can actually negatively affect accuracy. There is am extra cost , time, and chance of a total botch job involved.

You can take a sledge hammer to any of my clamp on blocks and the barrel will twist before the block will rotate. Yes, bedding my gas tube and block with loctite 620 green likely helps. I put a padded pipe wrench once on my clamp on block and was unable to budge it.

Clearance is a non issue. All your clearance issues are at the TOP of a gas block, not the bottom. Weight difference? Yeah, a few grams maybe. I refuse to have any set screws anywhere on my builds.

I just dont get it when builders ask for a  vastly inferior method of attaching a gas block to a barrel. I give AA a lump of coal for any of their set screw blocks. The XLP only comes with set screws. I will not buy or use one.

Jason from Syrac spent over three years designing, perfecting, refining and testing his new gas piston system. And it is a clamp on system. I feel that Jason has taken his original AA design and totally written a new page in the advancement of gas pistons. Even using this clamp on version the total weight is a mere 1.4 ounces more than a DI system and only fractions of an inch larger. I hope he does not bow to ignorance and come out with a set screw version. It would be a huge step backwards. Builders who would not take the extra time and expense for properly  milling dimples will have blocks that are much more prone to twisting or dislodging.

I am serious when I say that I do not understand the need or attraction of set screws over a clamp on system.

As far as Nib-x goes, I have to say I am underwhelmed with the performance of this plating vs the price. I am going to have all future builds extensively coated with the heat cure version of NIC's (Cerakote) Micro Slick. It is called P-109. The air cure version is not as hard...that is C-110Q Micro Slick. VERY few coaters even know about the P-109. Talk to either of these outfits. The price is half and the results are many times greater. Both outfits offer both versions of Micro Slick. You need to specify which one you want. Air cure is blue grey color. The heat cure is a matte black.

http://occustomcoating.com/micro-slick

http://madcustomcoating.com/micro-slick/

Jason promised a low mass carrier last year. I have seen gaps of up to three years between promises and actual arrivals of Syrac's products. So, who knows. I have ideas about lightening a standard Syrac carrier using the methods of Spike's low mass carrier....OR

It may be possible to simply mill a dimple in the strike face of an Adams Arms low mass carrier. I bet dimes to dollars that idea would work just fine if executed properly.



SHOUT OUT TO GUN SAFE:

Sir, you are a master builder. But why not try a Ferfrans device on the muzzle? They are very effective and make shooting a short barrel significantly (hugely) more pleasant. Just trying to help. Everything else you did is spot on. Very attractive looking SBRs as well as properly made. Kudos.

read this about the Ferfrans CRD.    This link contains other links to other alternatives (ie, Griffin QD)
http://www.recoilweb.com/the-ferfrans-crd-muzzle-device-system-36871.html

Here is the Ruger SR-556 as I'm currently shooting it. I have replaced the factory supplied furniture with BCM furniture and added some Ergo rail covers. Plus I added a 51T flash hider so I can use my suppressor.


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