Would there be any concern with drilling out the MR556 .055" vent to .063"/1.6mm, which is the factory correct 416 10.4" vent dimension?
That's why when they came out with it HK would only place them on new barrels that they could freshly drill the barrel port. If agencies/forces requested them be retro fit to existing service weapons they would replace the entire barrel assembly.
I was going to buy a third 416 barrel to attempt the redrill but got hit by some high taxes this year and the seller was gracious enough to understand.
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Last edited by RegularGuy461969; 04-28-2017 at 11:06 PM.
"Just because you're paranoid doesn’t mean they're not after you!"
Hk spec on the vented 10.4" 416 is 1.6mm barrel port and 1mm block vent.
The Mr556 measures 1.5mm on the barrel port and the block vent, same as the 14.5" 416.
The updated Norwegian AGR has a 1.6mm valve port and 1mm block vent, same as the vented 10.4", as well as a 1.4mm suppressed valve port.
I've been using the stock gas block with cut down Mr556 barrels, 10.4 and 11.5, which are otherwise stock (no port mods) suppressed and unsuppressed with various spring and buffer combos for years. That said, they're still overgassed suppressed, so I'm going to try the AGR.
FYI, I shoot my HK416 10.4" suppressed most if not all the time.
One solution for me was to have the heavier buffer, swap out the spring, etc.
The issue is that the HK416 10.4" is over-gassed with the suppressor so I felt that the heavier buffer, spring, etc. wasn't solving the root cause of the problem (which HK's solution evolved from vented gas block to currently adjustable gas block).
Anyhows, my solution then was to go with a 14.5" vented gas block. The diameter of the vent was clearly too large (I measured the 14.5" vs. 10.4" in another thread), but it worked when the suppressor was attached. Not an ideal solution because the HK416 10.4" would NOT cycle reliably when the suppressor wasn't attached.
So I was thinking of switching to the heavier buffer solution. After all, better a upper run harder than not run at all.
Thankfully, the vented gas blocks specific to the 10.4" are now available.
Granted the barrel diameter may be smaller than what is ideal, but I suspect it will work. Anybody installed the new 10.4" vented gas block on the older AG, AH, AI, etc. HK416 10.4" and shot it with the suppressor and without the suppressor?
Reliability of the upper to cycle especially without a suppressor?
I have the new 10.4" vented gas blocks sitting in my man cave, but have not had the time to swap them out.