Posted: 6/9/2026 2:03:28 PM EDT
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@Green0 Austin, I'm looking for my next rifle and looking hard at the Mk2, there's lots of info and options on the pages and I need a little clarity. Use case is general purpose all around rifle. Home def, SHTF, Carbine Class etc... not heavy use or hard firing schedule. So... Barrels- sounds like the 416r SS is a very good and accurate barrel but at the cost of barrel life, but will still remain accurate well past 10k rounds? I did see the 7k round test. Roughly, what is the MOA of the 416 vs the 4150CM. Did I read somewhere about 1moa vs 2moa for a good shooter? Seems like the Carbine is a 16" version of the Patrol/SBR, Yes? I normally run direct thread cans for weight and length considerations, but in your experience does some sort of muzzle brake/device make a difference. I see it's not recommended to run your Gas optimized BCG AND the adjustable gas block. I was under the impression the main thing the BCG does is to vent gas to the left vs. right. Barrel length 11.5, 12.5, 13.9-14.5 (.6 inches difference?), which is the 'sweet spot' when running a suppressor- K sized, for general use out to 300ish yards or so. I see the adj gas block has 4 holes but only 2 sizes. Could they be drilled for 4 sizes for non suppressed, HBP, and one for LBP cans? Lastly, if you were to go to your armory and outfit one of your rifles for yourself, what would it be. I know, lots of questions but I also like to hear the 'story' behind the product. |
Moderate-Length Barrel Evangelist
Joined:
Jun 2022
Posts:
4943
EE: 100% (11)
USA
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Originally Posted By bmarshall1: Barrel length 11.5, 12.5, 13.9-14.5 (.6 inches difference?), which is the 'sweet spot' when running a suppressor- K sized, for general use out to 300ish yards or so. It’s the sweet spot for velocity vs length, and Goldilocks with a K can with rail estate for lights or shooting off barricades or whatever. It’s also as short as I like unsuppressed with an A2 for blast and flash reasons. Shorter than that and you increasingly need longer open-tine flash hiders to keep flash manageable and muzzle blast becomes annoying. 13.5” is as short as I like to go for fulltime unsuppressed use, so 13.9” is the way to go for that. |
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I’m a firm believer in picking the right tool for the mission. There’s a big difference between sub-100 and 300 yards. Those are different rifles in my opinion. I’ve got a lot of ARs, each built for specific applications. 2 is 1, 1 is none n all that, suppress everything. |
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Originally Posted By bmarshall1: @Green0 Austin, I'm looking for my next rifle and looking hard at the Mk2, there's lots of info and options on the pages and I need a little clarity. Use case is general purpose all around rifle. Home def, SHTF, Carbine Class etc... not heavy use or hard firing schedule. So... Barrels- sounds like the 416r SS is a very good and accurate barrel but at the cost of barrel life, but will still remain accurate well past 10k rounds? I did see the 7k round test. Roughly, what is the MOA of the 416 vs the 4150CM. Did I read somewhere about 1moa vs 2moa for a good shooter? Seems like the Carbine is a 16" version of the Patrol/SBR, Yes? I normally run direct thread cans for weight and length considerations, but in your experience does some sort of muzzle brake/device make a difference. I see it's not recommended to run your Gas optimized BCG AND the adjustable gas block. I was under the impression the main thing the BCG does is to vent gas to the left vs. right. Barrel length 11.5, 12.5, 13.9-14.5 (.6 inches difference?), which is the 'sweet spot' when running a suppressor- K sized, for general use out to 300ish yards or so. I see the adj gas block has 4 holes but only 2 sizes. Could they be drilled for 4 sizes for non suppressed, HBP, and one for LBP cans? Lastly, if you were to go to your armory and outfit one of your rifles for yourself, what would it be. I know, lots of questions but I also like to hear the 'story' behind the product. There is a lot there to unpack. As far as accuracy, the 416r barrels are capable of around 3/4moa 5 shot groups with 69grain gold medal match ammo. Our 223wylde chrome lined barrels are made by the same vendor but I haven’t shot them much and we only bought them recently out of an attempted strategy to have more barrels so we could try to keep guns in stock. I would imagine they can shoot around a minute. A 5.56 chamber will cost a shooter ~1.5 moa by itself vs 223 wylde. Criterion core barrels are some of the only wylde chambered chrome bore barrels on the market. They have a good reputation for accuracy. Ours are also wylde. A lot of accuracy comes from the leade of the chamber- this needs to be snug to the bullet and concentric to bore so the bullet enters rifling centered and with minimal yaw. 5.56 leade is .003” loose allowing terrific yaw of the projectile during the leap from the case to rifling engagement. I haven’t really had amazing experiences with chrome lined chrome moly barrels. I think the chrome cracks and the barrels become difficult clean and cracked chrome probably damages the bore as it moves through the bore. A smooth bore finish to around 12RA supports reduction of barrel whip as the bullet travels through the bore. Beyond that, a second problem of barrel fouling becomes an issue where you don’t want a 6ra bore finish for example. My experience and opinion has been that 416R nitride is a better barrel for longevity of accuracy. We don’t have a lot of data here. I’ve shot chrome bore barrels in the military to 12,000 rds, and could not really comment on accuracy because they were probably 4.5 moa barrels when they were brand new aka the barrels never shot accurately. I can see accuracy testing online of JP barrels that are at 10,000rds in 416r with no nitride. They were shooting around 2.2-3.2moa for 5 rds. Criterion says 416r life increases 3-4 times with nitride, so thats around 35000rds at ~3.2moa if that extrapolates out. I have seen barrels run to 50,000 rds in test fire in 416r twice. They both had smooth bores with rifling that was obviously still present although one of the two was more faint than the other. We also got an 11.5 upper I believe back from barrel and hatchet at approximately 45000 rds which is around where they said they noticed accuracy reduction to the extent they wanted to replace it. I would recommend 12.5” as an ideal suppressor barrel. It combines mid gas with decent velocity. 10.5”s have a greater pressure at uncorking and produce more muzzle flash and sound. So you’re fighting the suppressor hard and 10.5’s are not nearly as reliable as 11.5’s or 12.5’s. The gas block plates have three settings- 2 different suppressed settings and two identical unsuppressed settings. This allows you to find a 180 degree side and have suppressed and unsuppressed on that side. We make a drill your own where you can size all 4 if you want. I don’t see why you couldn’t use a gas pocket bcg with an adjustable gas block. I just haven’t tested that to know if it improves anything. I would make mine a 12.5 mid gas mk2 the with a dual lok ez brake and run it suppressed all the time. I would probably use the adjustable block with the lbp plate and one of the DL5AM, HRT5AM, or HRT5KAM cans. The gun itself would be 416r nitride, basically bone stock (which is to say pretty premium and totally improved) except for the adjustable block which is a std option available at purchase. |
Austin, Managing Partner - www.GriffinArmament.com
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@Green0 THANK YOU for taking the time from your (I'm sure) quite busy day. 1- From your site, looking at the 12.5 SBR: Select BCG * We recommend choosing EITHER an adjustable gas block or the gas pocket BCG. Opting to run both simultaneously could impact reliability of the firearm in some cases. 2- Did I see something to the effect of you can treat a SBR like a silencer and 'ship to your door', maybe through CA, or is this for cans only. 3- Arggggg - I forgot number 3. |
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Originally Posted By bmarshall1: @Green0 THANK YOU for taking the time from your (I'm sure) quite busy day. 1- From your site, looking at the 12.5 SBR: Select BCG * We recommend choosing EITHER an adjustable gas block or the gas pocket BCG. Opting to run both simultaneously could impact reliability of the firearm in some cases. 2- Did I see something to the effect of you can treat a SBR like a silencer and 'ship to your door', maybe through CA, or is this for cans only. 3- Arggggg - I forgot number 3. No worries this week I was in my mastercam hates me hell with IT and support 3 days to regain access to my cam software to write a couple programs for prototype parts, so I was stuck waiting on that. Thanks for your interest in our products. I don’t think the bcg will impair reliability. I don’t know how or why some of this stuff is posted or becomes a belief. I think I may have mentioned I have no idea if they work cooperatively to get any benefit as I haven’t sound tested it. I don’t know about the sbr through CA. I think you technically can, but I’m not sure if they do that with us or not. I’m not averse of everything to do with sales. Sorry about that. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By bmarshall1: @Green0 THANK YOU for taking the time from your (I'm sure) quite busy day. 1- From your site, looking at the 12.5 SBR: Select BCG * We recommend choosing EITHER an adjustable gas block or the gas pocket BCG. Opting to run both simultaneously could impact reliability of the firearm in some cases. 2- Did I see something to the effect of you can treat a SBR like a silencer and 'ship to your door', maybe through CA, or is this for cans only. 3- Arggggg - I forgot number 3. I ran into something today, that was relevant. I discovered the adjustable gas block in unsuppressed will not lock back or cycle a 12.5" gun without using 5.56mm nato ammunition. It requires a .006" increase in gas port size to .092 to lock on PMC bronze in the "unsuppressed setting". Talking to AR build guys, this is the only barrel- 12.5 mid gas- that behaves like that- the others according to them still lock mags on std barrel ports. So in the future, if people buy a 12.5" gun with the AGB, we will be opening the port to .092" on that barrel, unless there are notes to only make that run with nato ammo unsuppressed, in which case they should leave the port .086" std. The HRT5 AM only works with the .078" larger of the 2 suppressed positions on the AGB LBP plate for the 12.5" gun, and it does that with the .086" port or the .092" port under the gas block in the barrel. That position was tuned to the Surefire RC3 and KAC CRS PRT cans. When the barrel gas port was .086 std (works with std gas block and PMC bronze), and the AGB was installed, the .078" setting made the HRT noticeably more quiet at the ear (maybe 3DB?) When the port in the barrel was opened to .092, it faded about 1/2 the advantage in sound. I think any higher backpressure can would still benefit from the AGB but the cans on the .078 port aren't gaining enough performance on the 12.5 with the .092 port to justify the AGB in my opinion. I think if we had a can like the Lazarus 6 or Optimus 6 that could run the smaller .07" it would still have merit via dropping enough pressure to merit the slightly higher disk pressure of the larger port. |
Austin, Managing Partner - www.GriffinArmament.com
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Originally Posted By bmarshall1: Barrel length 11.5, 12.5, 13.9-14.5 (.6 inches difference?), which is the 'sweet spot' when running a suppressor- K sized, for general use out to 300ish yards or so. For what its worth... I've been beating the absolute snot out of an 11.5 with a Recce5 and E-z brake for the better part of the last 3-4yrs. Issued agency duty rifle and can.. I run 2/3gun competitions regularly outside of work and we're on the range once a month at a minimum. Just ran a class last week. Heavy live fire day one (sub 1k rounds out to 200yrs), rest of the week was running simunitions (dirty boogers). We're running 18x 11.5's with Recce5s and we've probably surpassed 12-15k per gun since we purchased in 2022. Still running like champs. Only issue we've ran into on the Griffin side was the old gen-1 SOB buffer bumper tips and that got remedied within a week once I was able to temporarily replace all of ours on the team and get em sent in.. received at GA, replaced and kicked back out same day.. Customer Service has been on point. |
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Originally Posted By rmichael91: For what its worth... I've been beating the absolute snot out of an 11.5 with a Recce5 and E-z brake for the better part of the last 3-4yrs. Issued agency duty rifle and can.. I run 2/3gun competitions regularly outside of work and we're on the range once a month at a minimum. Just ran a class last week. Heavy live fire day one (sub 1k rounds out to 200yrs), rest of the week was running simunitions (dirty boogers). We're running 18x 11.5's with Recce5s and we've probably surpassed 12-15k per gun since we purchased in 2022. Still running like champs. Only issue we've ran into on the Griffin side was the old gen-1 SOB buffer bumper tips and that got remedied within a week once I was able to temporarily replace all of ours on the team and get em sent in.. received at GA, replaced and kicked back out same day.. Customer Service has been on point. Thats cool. If you guys can justify the spend, getting HRT556 AM’s you would probably really appreciate the reduction in backpressure and improvement to sound performance. Especially left handed guys or high volume shooters would see a big difference. At 15k you're not in a terrible place to potentially justify it. Sometimes you can even get some cash out of the cans in resale value. I’ld imagine a recce 5 at that point would still sell for 300$ or so on gunbroker. I see police trade ins sold by blue mountain supply llc fairly often. They sell used cans often at like 70% of original cost its crazy. We have people who have put 45000 rds on cans, but the low backpressure low toxic gas thing might be worth the upgrade. The shorter hrt5k is also capable of meeting or exceeding Recce 5 performance on a 12.5” gun with the ez brake, so if you guys run over ear electronic ear pro and want a lighter shorter can thats another option. Or in 6 ARC if anyone goes there, we are about to release an Optimus 6 AM and that is the lowest flash can for 556 that is low backpressure and also 6 ARC capable, but it is a little more expensive and heavier as a 1.75” od option with the 6mm overbore. |
Austin, Managing Partner - www.GriffinArmament.com