Last edited by InshallahTech; 11-20-2019 at 08:10 AM.
[QUOTE=InshallahTech;3609464] Chesapeak610 is putting together. Glad he’s getting accurate info. I’ll look and see if I can track down precisely and post if I find it.
I've done a bunch of searching on the forum here before I started this thread and it seems like what ends up "confusing" the issue is items that are sold as one thing but don't have the dimensions that match what comes on factory uppers. But I know that discussion started a whole ****-storm earlier. It also seems like some people are measuring a 10.4 gas block as "1mm" when the OEM one is (according to many posts here) .89-.9mm. That's NOT to say that what's being measured isn't 1mm, but I think it again confuses the issue.
Chesapeake, this probably doesn't help with what you're trying to do, but my factory 14.5" has a 1.5mm vent. Definitely bigger than the 10.4 ports everyone is quoting. Works perfectly suppressed or unsuppressed with Federal M193 and a SOCOM RC and OEM spring/buffer.
Hey Gatordev, I started down the path of collecting that info as well, but it’s just too much and varies from gun to gun. I have an MR556 16.5” upper that has a 1.45mm (.057”) vent which probably qualifies as a 1.5mm... I also have a VGB that came with my Brownells HK416 kit and that has a 1.7mm (.067”) vent, though I don’t know what the donor barrel was because that wasn’t included (nor was the bolt or lower receiver). So, I’m just sticking with 10.4” because that seemed to be the big unknown, especially for AGBs.
I’ll also say I’m still a bit perplexed, ToyCop has a 10.4” barrel with a 1.6mm port and an AGB with a 1.6mm N (Normal) port and a 0.9mm Vent and his operates fine with the HK buffer spring and buffer. Yet my 10.4” with a 1.7mm barrel port and an AGB with a 1.7mm N port and a 0.9mm Vent is under-gassed…even though the barrel and N ports are larger; WTH?? It must be something to do with the barrels then…
I suppose if we get more 10.4”/AGB samples, we’ll be able to state something that’s repeatable and anyone trying to use an AGB with a 10.4” barrel will have a workable formula. Or, they go the VGB route with a 1.0mm vent and it works; though that’s just too easy.
Or…”and then magic happens…”
Good point. The barrel was supplied by Hurricane Butterfly and made by Lothar Walther. My assumption is that the port would align precisely with the gas block port, but if it doesn't, my 1.7mm is moot. I've got to figure out how to check that. Again, good thinking, that never crossed my mind!
BTW, I'm going to start a new post called "HK416/MR556 10.4” Barrels/Gas Block Configurations that Worked" and supply the table and invite others to contribute. I just read the Nefarious Arms post "WTS HK416 10.4" Vented gas block" and someone said "We desperately need an informational thread capturing all the gas block and gas port info"; I'll give it a shot...
I simply don't trust ANY after market manufacturer of HK parts for the reasons listed above. Improper porting, obvious distain for the factory R&D and established protocol, poor QA/QC, and ignorance of all the factors involved in this particular operating system.
The addition of aftermarket parts only serves to muddy the waters and skew the results.