I have a CMT PDW lower on the way, this lower has a proprietary buffer system due to the built in PDW stock. Which complicates things a bit because the functionality of the PDW buffer system is sort of an unknown as the PDW lower is a unique and brand new product. The build will also include a 10.5 inch barrel with a carbine length gas system. I have decided an adjustable gas block is the way to go for this build. I have never used one before so could benefit from advice on which to choose. My understanding is the ranking per say goes something like this.
SLR
Syrac
Odin
seekins
I must say that I was leaning towards the seekins mainly due to price until a friend started to talk me into a SLR:
An alternative product that caught my eye is the Syrac Piston retrofit kit. It includes a bolt career, adjustable block and the piston, springs and so on. This kit caught my attention for three reasons.
Syrac is know for good adjustable blocks
weight. The piston kit weighs about the same as a block, and carrier (12.7oz)
price I found it for under 300, which is only a little bit more than I would spend on a block and carrier. Two things I need to purchase anyway.
Furthermore I have read that piston systems are recommend for SBR builds. I don’t have a suppressor presently but hope to get one within the next six months.
I would like to hear what folks have to say about this piston system, suggestions on adjustable gas blocks in general, and if you think the piston kit is the right way to go or if I am better off sticking with a DI system and adjustable block.
I wouldn’t say pistons are recommended for SBRs. If you’re implying that you should use a piston because you intend to get a suppressor, that’s more of an internet myth that constantly gets tossed around.
Anyone who has actually used a suppressor with a piston knows that it runs just as dirty as a DI upper. The back pressure caused by the suppressor blows all the crap back into the breech from the barrel regardless of the system.
Regarding adjustable gas blocks, SLR and Syrac have been reliable and easy to use from my personal experience. Haven’t used the others in person.
I also will recommend the SLR and Syrac. I did replace my old version of the Syrac with the SLR though. Have 4 SLRs now. Thousands of rounds through SLRs on SBRs with and without suppressors without issue. I agree with Slippers on the DI and Piston. I feel the Adj gas block along with E carrier running a can on a DI sbr is the cleanest I’ve run.
im not a fan of the Seekins as the adjustment is very hard to access. I have an Odin and a Syrac Gen 2 on my SBR’s and they work as advertised. The Odin may be my favorite but it is a higher profile than the Syrac so it may limit your handguard choices.
I’ve got an SLR for an 11.5 that I’m hoping to get around to installing and shooting within the next couple weeks. With NFA wait times like they are, no telling when my omega will be free to try with it though…
I had a look at the Micro MOA website. It looks like these AGBs have only two or three adjustment positions. Reminds me of the Noveske Switchblock settings for Suppressed or Unsuppressed. It does not appear that this would be good for my purposes. Am i missing something?
Thanks all for your input. One more to add to the list, JP Enterprises AGB. Anyone used this one? not the model that is JP branded but made by Syrac. Thanks
The only thing you missed is the regulator plates are “adjustable” by way of a numbered drill bit set. You can buy blank plates that you can “adjust” by going up in size until the gun functions. The “infinitely” adjustable set screw type gas blocks just means a PITA when you go from suppressed to unsuppressed. You either have to count clicks or go through a function test every time you want to change settings. The 2 or 3 position plate gives you set values for a particular setting on a whim and requires nothing more than something long and pointy to change settings like a bullet or… a rock or something.
I’m building my “last one” gun right now. I’ve neither handled nor seen any of the products you listed, but I’m dead set on the Govnah based purely on features and the fact that I’ve not seen any hate for them as a company. I’m going with 11.5" on this one and figure I’ll buy a barrel with the govnah attached just to make it easy. Their accuracy claims are pretty extreme, so I’m a little leary of it all being too good to be true but there’s only one way to know for sure.
The fitment issues posed by the Micro MOA part are no less a PITA than any other style adjustable gas block. It’s just an option that some may find useful.
The real solution to this conundrum is a dedicated upper built with a barrel that has a correct gas port. If your going to build a suppressed upper, why not shoot it suppressed all of the time? What’s the benefit of shooting an SBR without a suppressor?
I just picked up an Anderson adjustable gas block. Even got a nice detent system for the adjustable set screw. Pretty good price too, can’t remember exactly but I believe it was < $60
I agree that the correct gas port size is probably the simplest option. However, it appears that the OP is concerned that he may need to make adjustments based on the untested PDW stock setup he’ll be running.
A similar, simple option would be the insertable gas ports from BRT. I’ve used them on a build, and I was happy with them.
I run the MicroMOA on my 11.5, and I love it. If you’re running a compatible forend, I’d definitely recommend it. I think I’ve fired all of one mag through my SBR unsuppressed, just to test function, but I figure it’s nice to have the option when you don’t really sacrifice anything to get it. The unsuppressed setting could also function as an, “adverse” setting while running suppressed, I suppose, though I’ve never found it necessary.
The only other adjustable GB I have any experience with is the Syrac my friend has on his .300. He’s happy with it, but adjustment is more of a chore. I think it (and the similar options) would be a good choice if you’re just trying to fine tune the gas.
Both function as they should. However I had better fitment on the SLR…Though this could just as easily be the barrel specs. My Syrac leaked some until it sealed itself while I had no leaks with the SLR.
I also like the leaf spring design of the SLR.
Biggest reason is simple. SLR’s customer service is great. He really goes out of his way to take care their clients.
That’s interesting. I bought a set screw SLR gas block before they moved to the leaf spring design, and then before installing it called to exchange it for a clamp-on version. In the time between buying the first gas block and calling to ask about swapping, they changed the design over to the leaf springs and I was sent one of those. Between that and the other interactions I’ve had with them I’d agree that their customer service has been stellar. From what I can gather about Syrac it seems that their customer service is non-existent.
I also have a few Syrac gas blocks, and I prefer the spring/detent design (as well as the SLR version before the leaf spring) because I read about the leaf spring retaining screw coming out of someone’s SLR gas block and wasn’t comfortable with that possibility. That’s not going to happen on the Syrac gas block. I haven’t installed any of the Syrac blocks yet, but when I test-fit one onto a barrel, it left a line where the the gas port hole is in the block. I’m assuming that’s a burr or something that wasn’t cleaned up when they drilled the hole. If that’s the case then it might explain why yours leaked. I’ll have to look at that when I’m ready to install mine.
SLR, get it. Small enough to fit in even my relatively tight/small geissele mk1 and mk3 rails, both are clamp on gb’s. You can adjust it very easily, solid clicks. I haven’t tried any others but I feel no need to, there’s no way any other gas Blck could offer something the SLR sentry doesnt
Its going on a SBR with a PDW buffer system, which I believe is potentially a high pressure system. The adj block is to ensure proper cycling with different types of ammo, reduced recoil, and shell ejection pattern (I am using a slick side upper).
I ordered the SLR Sentry 7. Now I am on to selecting the final part for my build, the BCG. I just discovered adjustable gas keys… would there be any point in running an adj gas key in combination with an adj gas block or would the configuration simply be redundant and confusing?