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Posted: 9/12/2025 8:25:13 PM EDT
[Last Edit: Green0][Edited]
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On the range with Arfcom member Amphibian demonstrating the Griffin gas block that owes its design to the MICROMOA Govnah gas block. MicroMoa sold us the patents a few years back and we finally were able to bring the product to market. The podcast with Robert on the history and development of the block will be live in a few hours. Digital manual link: https://griffinarmament.com/wp-content/uploads/2025/09/Adjustable-Gas-Block-Manual_small-compressed.pdf  Griffin Armament Adjustable Gas Block https://griffinarmament.com/shop/griffin-adjustable-ar-15-gas-block/  Dwell Time Podcast #89: Griffin Adjustable Gas Block Featuring Robert Soong of MICROMOA  Griffin Adjustable Gas Block - User Interaction Demonstration |
Austin, Managing Partner - www.GriffinArmament.com
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I saw the e-mail about this this morning. I really like this concept of not having a threaded adjustment screw driven into the path of the gas as the mechanism for flow restriction, and I'm not a fan of the bleed-off approach. It's nice to see more companies taking a stab at improved adjustable gas blocks. Faxon released one a few months ago that moves the gas tube back and forth to restrict flow, so that's a couple of non-screw adjustable GBs introduced mid 2025. I think it's nice to see innovation in the direction of less maintenance and higher reliability of adjustment mechanisms in gas blocks. Keeping maintenance easy sure helps KISS stay simple by not demanding more extensive maintenance routines. Speaking of that, does the GB require any special maintenance as the round count rises to maintain adjustability? As there's a very good chance (at any given time) that my next upper build is not 5.56/.223 (only around 20% of what I build is), I think it'd be nice (at some point) to see plates made for other calibers/gas lengths, or firm suggestions on which (if any) plates that work with other calibers at other gas lengths, or a nice table of suggested diameters to drill the custom plates to for other calibers/gas lengths. I see how KISS the setup/installation is for 5.56 & .300 BO, and how not KISS it is for anything else. I get it, 5.56 is the most common one, so you work the market segment where the most profit is, especially as you release a new product. Just throwing it out there, it'd be neat if you offered a suppressed/off customizable plate, too, which a chamfered+0.033" diam hole, and a completely blank position -- thinking of integrally suppressed .300 BLK or other subsonic builds, primarily. Either way, next suppressed 5.56 upper I do, I'll keep this in mind. Good job to Griffin once again. |
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I don't believe any maintenance is required. the gas checks on the bottom also cut carbon as the plate is moved, and the counterbores on the holes give carbon a place to go so it doesn't build a physical shelf. The part should just work. The inconel spring can't corrode, and the clearance at the front and back of the disc / plate slot allows carbon to leave the system. I would agree that I don't love the screw / pin covered port concepts as that pin has low mass and can become eroded and as spun it seals differently once the shape of the pin end is irregular. Spun pin / screw systems also don't have 2 logical positions they are more like infinitely adjustable which doesn't play well with getting back to an exact setting when the suppressor is mounted or removed. I would not want to block gas with a tube as that is like .035 wall and not strong enough to be optimal for that. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By bfoosh06: Thank You for the port size list ! That helps with my decisions. Glad it helped. My intent was for that to hit the product pages. We’ll get it there next week. The install manual is also going to be a PDF upload by probably Wednesday. This was a two year project and at a point we get a little stir crazy to launch. |
Austin, Managing Partner - www.GriffinArmament.com
| What buffer weight are you guys basing those gasport sizes on? I have been using similar gasports with my mid and carbine length rifles setup to run suppressed 100% of the time. I tune mine to work with a standard buffer and spring so there is very little gas needed to cycle the rifle without the extra weight of heavier buffers and springs. |
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We set these up with out standard AR-SOB buffer which is H2 weight. The barrels were our 223 wylde barrels and the ammo 55grain TAP commercial. We know whether people say it or not they want their rifles to run commercial ammo as well as nato. Digital manual link: https://griffinarmament.com/wp-content/uploads/2025/09/Adjustable-Gas-Block-Manual_small-compressed.pdf |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By Green0: [...]The install manual is also going to be a PDF upload by probably Wednesday. This was a two year project and at a point we get a little stir crazy to launch. Originally Posted By Green0: [...]The install manual is also going to be a PDF upload by probably Wednesday. This was a two year project and at a point we get a little stir crazy to launch. Originally Posted By Green0: [...] Digital manual link: https://griffinarmament.com/wp-content/uploads/2025/09/Adjustable-Gas-Block-Manual_small-compressed.pdf So, you beat Wed. by most of Tue. for that PDF. Your deeply-rooted enthusiasm is something no company just out to make a quick buck can replicate. I appreciate that. |
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For anyone who is interested, here is some more technical information on the Griffin Armament Adjustable Gas Block |
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Originally Posted By PreacherOfGadget: So, you beat Wed. by most of Tue. for that PDF. Your deeply-rooted enthusiasm is something no company just out to make a quick buck can replicate. I appreciate that. A guy in our marketing department worked hard on that and helped us to accomplish that. I appreciate your compliments. I passed them on to him. |
Austin, Managing Partner - www.GriffinArmament.com
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The gas is going up so the plate is pushed into contact with the top of the slot. The plate only has like .001" of tolerance or so. There were military tests of things like the diameter fit on a gas tube and the system worked until the gas tube was like .008" undersized. There is only so much leakage you can have from .001" tolerance on a .096" hole, and the gas checks are re-routing gas linear rearward so it doesn't go sideways. As it is the block has .0005" tolerance on the something like .125" hole normally. The Gas tube is a .0005" or so slip, the carrier key is a similar slip to the tube, and the tail of the bolt at .250" diameter has something like .0015" tolerance and no gas rings. So there are plenty of tolerances in the system already and they are well tolerated tolerances. MicroMoa was in business something like a decade, so they fielded a lot of the blocks made on this principle successfully, indicating this is just not a significant issue. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By JAG05: Cool. Thanks for the explanation! No problem. Another way of understanding is looking at the application of a slip fit suppressor mount (bayonet attachment) such as our M4SD A2 mount interface- the mount has a gas check groove in the comparatively huge .864" hole, and our mount is .001" or so slip fit tolerance so it seals up pretty well, but the smallest A2's are like .004" slip and they work fine and the suppressor may have a puff of gas in the back but the meter doesn't pick up additional noise. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By Green0: I don't have any 6 arc rifles, so I wouldn't know the port sizes. That's a drill your own plate application most likely. The port sizes we do make are listed below: https://www.ar15.com/media/mediaFiles/19386/Adjustable_block_hole_sizes_2-3623544.jpg Everything on the chart makes sense to me, except the mid gas LBP sizes. All other length gas systems, the small and large hole sizes are smaller than what my gas ports are in different lengths and they are pretty average port sizes. But the mid length LBP sizes seem large. My mid length 14.5 and 16 barrels have .074-.076 gas ports, so .070 is a step down, but .078 large hole is larger than my barrels port size. Carbine and rifle length LBP large holes are smaller than my respective gas ports. Am I missing something? |
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Our mid gas barrels are .086” ported. They have wylde chambers which may increase extraction force. If we drop back even to .082” we would have issues like failure of bolt hold open on the last round of a magazine with pmc bronze. I have heard of barrels with smaller mid gas ports, but am not really familiar with how they cycle when .003” smaller results in issues in our mid gas barrels. It might be something that is possible when the chamber reamer is like the 5.56 equivalent of the .0015 oversized, loose 7.62 nato chamber and throat in an m134 minigun, and the chamber is chrome lined. Our barrels are set up to run commercial ammo because if they don’t, customers want us to open ports and that is expensive work like the equivalent of building the gun a second time for no pay, and in those cases it can be required twice for one gun, as a users ammo can be a variable. The only exception is .300blk. Our .300blk requires a conventional suppressor and 220 Remington subsonic to cycle in subsonic. Sometimes a high backpressure muzzle device after 200 rd break in can get light ammo like s&b190grain running. With an lbp can my guess would be subsonic would not run in our .300bo. |
Austin, Managing Partner - www.GriffinArmament.com
| Oh wow, ok. I have never seen or heard of mid length ports being .086”. I had a White Oak Armament 16” mid length SPR barrel that was .082” and was way overgassed. Every other 14.5/16” mid length I have is in the .074-.076” range. So guess I should go with the drill your own option for the mid length setups then. |
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There might be a little mountain out of mole hill thing going on, as people buy FN SCAR's all the time, and the suppressed setting will run with no suppressor attached- AKA it is not even close to a suppressed setting, whereas our plates are actually tuned for our barrels. I would imagine the chamber makes the difference if anything. I know we use the same gas port for all our mid gas barrels regardless of length (which is odd but it works). I also know that when I made a 13.9 mid prototype from a 16" from a really early run back when we were opening gas ports for several of the first customers in 2014, I opened that smaller port to an .082 port on the off chance it would cycle, and it would not cycle with the .082 port with PMC bronze ammo. I know it didn't lock back and I don't even believe it stripped the next round from the magazine. We also run H2 weight buffers in our guns. A lot of companies run CAR, but car is less reliable for closing the bolt than H2. The reality is the gas ports on rifles with most manufacturers are not over gassed. The belief that all barrels are identical that some people have because they have a barrel with a smaller gas port that runs, probably has something to do with a sloppy chamber or a lubricating quality of a coating or their use of Nato ammo only, or that the manufacturer of that barrel might have misrepresented the gas port size to them, or something else. Barrels lose at least a minute of accuracy with a 5.56mm nato chamber. I don't really love that trade off. The HK416 has a chamber that is essentially 223 wylde and it is known for its better accuracy and is issued by the military. I watched Focus Tripp shoot a Geissele gun and a Mk1 in one review, swearing that our gun was overgassed because he took it apart and measured the port, and the ejection patterns of the two rifles were identical, standing in juxtaposition of his argument. < he didn't really notice that but it was obvious in that video, and other people who watched it made that observation. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By muniti: Can you turn off the gas with these? Between settings you can, but not by design at a detented setting no. Turning off the gas is a novelty. It doesn't really have any practical purpose I can think of. |
Austin, Managing Partner - www.GriffinArmament.com
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Just a thought, just thinking out loud.... and this was brought up on another forum. Could a "disc" be made for switching between a ( 300BK ) subsonic and supersonic ammo ? Or any recommendations for the "drill" your own disc , gas port size wise for the 300BK ? |
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Originally Posted By AR_Dale: My Micro MOA upper has 3 holes in the Govnah plate .073 normal, .055 suppressed, .082 normal but dirty or weak ammo. It's a 12.5" mid gas. I use a Specwar 556K I also bought a extra blank plate I can make what every. It sounds like you have the Daniel Defense MK18 plate Robert at MicroMoa @amphibian mentioned. He said .082 matched the factory oversized port, .074” essentially fixed the reliability issues of the old consumer spec barrel, and .055” would be the suppressed setting. Our 11.5 carbine gas barrels have .073 ports whereas our 12.5 mid gas guns have .086” ports in the barrels which are .223 wylde chambered and probably require more gas to extract than 5.56 nato chambers. They both run rather optimally with those. Our plate normal holes are pass throughs, not intended to match a barrel port, while our suppressed holes are tuned. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By Green0: There might be a little mountain out of mole hill thing going on, as people buy FN SCAR's all the time, and the suppressed setting will run with no suppressor attached- AKA it is not even close to a suppressed setting, whereas our plates are actually tuned for our barrels. I would imagine the chamber makes the difference if anything. I know we use the same gas port for all our mid gas barrels regardless of length (which is odd but it works). I also know that when I made a 13.9 mid prototype from a 16" from a really early run back when we were opening gas ports for several of the first customers in 2014, I opened that smaller port to an .082 port on the off chance it would cycle, and it would not cycle with the .082 port with PMC bronze ammo. I know it didn't lock back and I don't even believe it stripped the next round from the magazine. We also run H2 weight buffers in our guns. A lot of companies run CAR, but car is less reliable for closing the bolt than H2. The reality is the gas ports on rifles with most manufacturers are not over gassed. The belief that all barrels are identical that some people have because they have a barrel with a smaller gas port that runs, probably has something to do with a sloppy chamber or a lubricating quality of a coating or their use of Nato ammo only, or that the manufacturer of that barrel might have misrepresented the gas port size to them, or something else. Barrels lose at least a minute of accuracy with a 5.56mm nato chamber. I don't really love that trade off. The HK416 has a chamber that is essentially 223 wylde and it is known for its better accuracy and is issued by the military. I watched Focus Tripp shoot a Geissele gun and a Mk1 in one review, swearing that our gun was overgassed because he took it apart and measured the port, and the ejection patterns of the two rifles were identical, standing in juxtaposition of his argument. < he didn't really notice that but it was obvious in that video, and other people who watched it made that observation. Yeah I run H2 and springco blue in in pretty much everything as well. A couple others have A5H2 with springco green. |
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Originally Posted By RustyShackleford1980: Yep, this beats the screw pin. Pretty great idea. Thanks. One of the gas tubes Carbine length straight, was miss-packaged normal bent. If anyone got one of those, CS is in the process of sending a straight tube and return ship envelope for the bent tube. Sorry for the packaging label error. |
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| I haven't been watching this website regularly for some time, but I'm glad I checked today! I was disappointed when the Govnah gas block was discontinued before I could get one. I'm very excited that this revised option is out now, as I think it will be great for the two .300 BLK uppers I'm putting together. The applications for this type of gas block seem pretty vast, and I'm super excited that the blank plates will be offered to allow true customization to the end user. |
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Do you have any plans to offer these for .625" diameter gas block journals at any point? Most of my builds are with .750" dia. journals, so I understand there's a demand difference. I was/am piecing together a "made in southern WI" build using a Criterion Core barrel with a .625" journal, and realized I was lacking in adjustable gas block options meeting my criteria. |
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