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Posted: 8/19/2026 8:44:46 PM EDT
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What would you guys use for a belt fed 5.56 build? I'm thinking Haynes 282 or maybe Nickel 625x for the material. I'd like to keep flash and dust down, I don't need the quietest suppressor. @Green0 - which of your cans would you recommend? |
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I don't have first hand experience with the belt fed 556 closed bolt systems. We were kind of given the impression that there are some systems that are capable of possibly north of 350rounds cyclic without cook offs (these are really niche systems that have pretty crazy cooling devices, and I can't completely verify those details as I haven't literally conducted the safety testing). We were also told the guns could do a lot higher round counts in about 13 minute course of fire- I believe that was upward of around 750rounds- something like 40 rounds a minute after peak operating temperature was obtained. That schedule involved 100 round belts, aimed burst fire at intervals, and ~40 second reloads. <obviously some pacing of the guns was needed as they are developed from direct gas ar15's essentially, and I apologize for having not photographic memory of what was described to me on the phone. We are working with Red Right Hand to make a can ideal for that type of operating parameters, but that is light of the capability of the open bolt M249, which we make a can marketed only to the government for. We have a prototype in the printer tonight that is Dual Lok and around 25 ounces, and the idea behind it is to kind of par those capabilities with some good safety margin, without being overly heavy. My plan is to send it to Red Right Hand, and let him validate it for his open bolt belt feds and if he likes that, we could offer that for people to have a more tailor made can to accompany the guns. The HRT5 was tested to 300 rounds which is very close to that level of durability, however obviously that's getting extreme for a 16 ounce carbine can and we wanted to add some weight, increase volume, and also give the can a 6ARC bore to give a little better hot barrel safety to the system. |
Austin, Managing Partner - www.GriffinArmament.com
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Thanks for the feedback. I was looking at the RRH upper and almost bought it. Ended up ordering all the parts for a LimaSix/IGM7 and RRH's handguard. Since I'm paying for the ammunition, I probably won't run it too hard very often. I'm definitely interested in your new can, it sounds like a good option. |
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I found a new old stock AAC MG-SD at a FL SOT for $900 for my M249, but I haven’t gotten it really hot yet. Its core is all Inconel and is .30 cal so I’m planning to put a mount on an M60 barrel as well. MG-SD used a special 90T mount and not AAC’s usual 90T mount. It was only offered in 2 different thread pitches (for M240 and M249). Google just informed me: Nickel 625 and Inconel 625 are the exact same material. "Inconel" is a registered trademark name owned by Special Metals Corporation, while "Nickel 625" (or Alloy 625) is the generic industry term. Both share the unified numbering system designation UNS N06625. So I learned something today.  EDIT: MG-SD is Inconel 718 and not 625. Apparently the 718 has much greater tensile and creep-rupture strength at elevated temperatures. https://alloyaccu.com/inconel-625-vs-718/ |
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I don't have access to an actual belt fed, but with my humble FRTs and Magpul D60s I have performed a few experiments. The Surefire RC2 held up fine against 200 rounds in about 1 minute. In a few days I'll have my YHM Turbo T3, which I've chosen to be my "IAR" FRT rifle suppressor, using a Surefire HUB mount on a Surefire brake mount in order to mitigate wear as much as I can. |
I don't see no Americans. I see trespassers.
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I have a TBAC hub Spiro on my L6. I'm reasonably sure the weapon will overheat and fail before this suppressor fails. The hub mount and muzzle brake is the 718 inconnel Hesion Bow system from Irregular Defense. There is very little cyclic rate change and no gas in my face with this suppressor. 200 round belts in less than a minute has not caused any damage. https://thunderbeastarms.com/products/spiro https://irregulardesigngroup.com/hesion-bow-hub-adapter/ https://irregulardesigngroup.com/hybrid-flash-hider-md/ |
Middleofnowhere, Nebraska
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I have a Sico Velos 762 with a 556 end cap on my 18" Lima 6. It sounds good and the gas to the face isn't really noticeable. I recently got a Velos 556 and a Velos 556K but haven't shot them yet. I plan to put the V556 on a 11.5" Colt IAR upper and the V556K on a 16" Colt IAR upper. The only gripe I have with the Velos cans is that they use Sico Charlie mounts instead of HUB mounts. I have a couple of ECCO Charlie to HUB adapters to fix that if I put them on a non ASR host. Not doing much shooting lately because it's too damn hot. |
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Originally Posted By KitBuilder: Google just informed me: Nickel 625 and Inconel 625 are the exact same material. "Inconel" is a registered trademark name owned by Special Metals Corporation, while "Nickel 625" (or Alloy 625) is the generic industry term. Both share the unified numbering system designation UNS N06625. So I learned something today. Nickel 625x is not the same material. It is a proprietary alloy we specified out to a powder material manufacturer and had manufactured, and lab tested (multiple samples) against slm 625 inconel printed and heat treated identically off the same slm machines (results for slm 625 and nickel 625x used in our data sheet). We submitted a utility patent on the alloy, and the test results showed it is superior to 625 and 718 inconels for slm sound suppressors via much greater strength and higher mechanical and environmental service temperatures. We have a data sheet on our website. If you add Griffin Armament to the 625x in the search google AI says a lot of other stuff that doesn’t really reflect total AI understanding of the alloy but at least it doesn’t say the alloy is the same as 625 inconel. There is a lot of nuance to understand the alloy but it is a pretty exceptional alloy in the nickel superalloy family and is fully custom formulated. Another cool thing about it is that it is the first alloy developed solely for sound suppressors. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By Green0: Nickel 625x is not the same material. It is a proprietary alloy we specified out to a powder material manufacturer and had manufactured, and lab tested (multiple samples) against slm 625 inconel printed and heat treated identically off the same slm machines (results for slm 625 and nickel 625x used in our data sheet). We submitted a utility patent on the alloy, and the test results showed it is superior to 625 and 718 inconels for slm sound suppressors via much greater strength and higher mechanical and environmental service temperatures. We have a data sheet on our website. If you add Griffin Armament to the 625x in the search google AI says a lot of other stuff that doesn't really reflect total AI understanding of the alloy but at least it doesn't say the alloy is the same as 625 inconel. There is a lot of nuance to understand the alloy but it is a pretty exceptional alloy in the nickel superalloy family and is fully custom formulated. Another cool thing about it is that it is the first alloy developed solely for sound suppressors. |
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Well I would recommend something meant to reduce backpressure based on my experiences with a F1 (basically a Turbo K clone with a 6.5mm bore) on my 12.5" L6. I will often get flame out of the feed port or ejection ports in the upper receiver and assume that there is unburned powder coming back through the gas port. I get no flameout in my 16" L6 with no can. ETA: Lol and if that wasn't enough to consider the flash suppression nonexistant, 2 foot "mosin sbr" like flames out of the can at night  Eta2 
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I'll have an inconel Tisha and M4SD-L AM to try soon. Maybe I should have gotten the 3 AM but I don't really intend to use it on the L6. I still have a $275 Spartan II that will ultimately end up on my short L6 because if I'm going to burn something up it may as well be my oldest, least expensive rifle can. But that's definitely not going to help with flow either. |
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Originally Posted By Kuraki: Well I would recommend something meant to reduce backpressure based on my experiences with a F1 (basically a Turbo K clone with a 6.5mm bore) on my 12.5" L6. I will often get flame out of the feed port or ejection ports in the upper receiver and assume that there is unburned powder coming back through the gas port. I get no flameout in my 16" L6 with no can. ETA: Lol and if that wasn't enough to consider the flash suppression nonexistant, 2 foot "mosin sbr" like flames out of the can at night Eta2 https://www.ar15.com/media/mediaFiles/125898/5000-3817547.jpg We made a L6MG can this last week. We're shipping one to Red Right Hand for T&E. I've shot it on an M249 saw. It reduces sound really well- like on a para its 134DBA peak ear. On a long barrel it's 132DB peak ear. The flash is non-existent after the first 3 rounds, and it's a 6mm arc bore- generous for the 5.56mm so the belt fed doesn't have issues. No air quality issues IMO firing automatic with the M249. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By Green0: We made a L6MG can this last week. We're shipping one to Red Right Hand for T&E. I've shot it on an M249 saw. It reduces sound really well- like on a para its 134DBA peak ear. On a long barrel it's 132DB peak ear. The flash is non-existent after the first 3 rounds, and it's a 6mm arc bore- generous for the 5.56mm so the belt fed doesn't have issues. No air quality issues IMO firing automatic with the M249. |
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Originally Posted By Green0: We made a L6MG can this last week. We're shipping one to Red Right Hand for T&E. I've shot it on an M249 saw. It reduces sound really well- like on a para its 134DBA peak ear. On a long barrel it's 132DB peak ear. The flash is non-existent after the first 3 rounds, and it's a 6mm arc bore- generous for the 5.56mm so the belt fed doesn't have issues. No air quality issues IMO firing automatic with the M249. Awesome |
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KAC makes an MG can but I don't think they have ever shipped the mount for it yet (lol) Allegedly, the NT4-PRG and CRS-1 were designed with the idea that they might be thrown on belt feds and they're low back-pressure Basically, you're going to want about a pound and a half of Inconel if you want it to last and low back-pressure won't hurt |
| I'd have to trust Griffin, not that others wouldn't be suited. I'd also say just today I watched a video today by Micah(?) used to work the guy I can recall his name. Anyway, he was ripping through belts of 556 on a Tisha, getting the gun hot enough to cook off rounds and it seem to hold up fine, Inconel I assume. |
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Originally Posted By bmarshall1: I'd have to trust Griffin, not that others wouldn't be suited. I'd also say just today I watched a video today by Micah(?) used to work the guy I can recall his name. Anyway, he was ripping through belts of 556 on a Tisha, getting the gun hot enough to cook off rounds and it seem to hold up fine, Inconel I assume. Good to hear. |
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You could run a lot of cans. It really depends on how hard the lima 6 can/will be run whether a specific can is ideal or not. Some of the limas have heat sinks on the barrels and tubes and might be more able to run some cans to failure. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By PacificNic: KAC makes an MG can but I don't think they have ever shipped the mount for it yet (lol) Allegedly, the NT4-PRG and CRS-1 were designed with the idea that they might be thrown on belt feds and they're low back-pressure Basically, you're going to want about a pound and a half of Inconel if you want it to last and low back-pressure won't hurt The NT4 PRG is a nice can, but a lot of little holes at like .070" are not likely to play nice with high round count belt feds. The can is kind of managed pressure to begin with, and as those holes close in, you're likely to see pressure increase. I bet their belt fed can is way more purpose built with the belt fed considerations in mind. There were units that ran NT4's so yeah it can be done with conventional pressure cans, but its not optimal for running the machine gun hard. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By Green0: The NT4 PRG is a nice can, but a lot of little holes at like .070" are not likely to play nice with high round count belt feds. The can is kind of managed pressure to begin with, and as those holes close in, you're likely to see pressure increase. I bet their belt fed can is way more purpose built with the belt fed considerations in mind. There were units that ran NT4's so yeah it can be done with conventional pressure cans, but its not optimal for running the machine gun hard. |
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Originally Posted By jaqufrost: How long do you think it will take before your belt fed can is available to order? Red Right hand's can is going out this week (It's approved today). It's a matter of whether he likes it enough to recommend it. We could be in production in a week if he concludes testing favorably, and that would put them out about a month. He's closer to the market, so if he doesn't like it, it won't exist. I think we have a pretty strong chance. This is our 4th belt fed can R&D project this year so we've had a lot of development time to get close to something pretty developed. |
Austin, Managing Partner - www.GriffinArmament.com
| I'm in a similar situation. I've got a spare Recce 7 mod 4 and Rugged Surge so I am debating which to use or to get something specific. I would think the Recce 7 would be better for backpressure but might just try them both. I don't plan on wildly dumping rounds to try to break something, so I would imagine either would be fine. I will definitely follow this thread. |
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Originally Posted By fordkicksass: I'm in a similar situation. I've got a spare Recce 7 mod 4 and Rugged Surge so I am debating which to use or to get something specific. I would think the Recce 7 would be better for backpressure but might just try them both. I don't plan on wildly dumping rounds to try to break something, so I would imagine either would be fine. I will definitely follow this thread. We have run the recce 7 to 200rds on a 240 many times. I would imagine in 5.56 the can could go to 300-400rds before damage and with a little cooling time built into a schedule it should go further. The .30 cal bore helps alot vs a dedicated 5.56 bore. Not sure of course on backpressure. The adjustable gas would really help to be optimized for the can, as that will lower pressure and rate of fire. |
Austin, Managing Partner - www.GriffinArmament.com
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