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Discussion Starter #1
I remember the barrel nut torque is 90lbs for MR223.

But what about..

-Castle nut
-Handguard grip nut
-Muzzle device
-Grip screw

Any official torque guides for these?
 

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Where do you get these info from?
As stated above, off the top of my head. Original source, though, is mainly this forum, following armorer course threads and whatnot. Torque values are inscribed directly on specific parts: handguard rail locking screws (new style, hexagonal w/ slot) and flash hiders (237803, 211719).

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-Barrel nut - 110 +-10 Nm, retorque after 10,000 shots
-Castle nut - 60 +-10 Nm
-Handguard grip nut 7 +-1 Nm
-Muzzle device - not covered in my copy of Maintenance Manual (edition 2009)
-Grip screw - not covered in my copy of Maintenance Manual (edition 2009)
 

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Just checked the A3 Operator’s Manual; torque value for 237016 flash hider is 60±5 Nm; the locking screw for handguard breaks off at a torque of 14 Nm, torque value is 7±1 Nm. BTW it should be a sticky thread.
 

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Discussion Starter #9
Mr223a1 what do you mean by handguard screw breaks off at 14nm and then add torque value 7nm?

Litterally breaking lile damaging the screw at 14nm but should be tighten to 7nm? Did I get you right?
 

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Mr223a1 what do you mean by handguard screw breaks off at 14nm and then add torque value 7nm?

Litterally breaking lile damaging the screw at 14nm but should be tighten to 7nm? Did I get you right?
The locking screw for handguard may be safely tightened until the torque of 7±1 Nm is reached. To prevent damage to the handguard, the locking screw has a defined breaking point; it breaks off at a torque of 14 Nm. When tightening the screw, keep within the torque; if you exceed that value, the screw will brake off. That's basically what the manual says. As you may note, there is, however, a considerable margin of safety.
 

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To prevent damage to the handguard, the locking screw has a defined breaking point; it breaks off at a torque of 14 Nm. When tightening the screw, keep within the torque; if you exceed that value, the screw will brake off. That's basically what the manual says.
This is interesting info. My manual does not state that, but weak point in screw is kind of obvious. And now I know why screw has slot for flat screwdriver on threaded end - to allow easy removal of threaded part after screw was broken. HK really thinks about everything.
 

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This is interesting info. My manual does not state that, but weak point in screw is kind of obvious. And now I know why screw has slot for flat screwdriver on threaded end - to allow easy removal of threaded part after screw was broken. HK really thinks about everything.
A very good point, indeed. We can't deny their ingenuity. If it hadn't been for their stubbornness (HKey instead of KeyMod, or even better Mlok etc.) they would have truly been the best - not only in the engineering.
 

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German engineering at its best:)
Yep, no doubt about it. Too bad they suffer from "not invented here" syndrome. QD rail attachment points? Who needs them? Rail Interface? No way we could use anything else but our own standard! And we don't make anything for HKey except for Picatinny rail segments, but so what?

That being said, I currently own 7 HK firearms, another 2 incoming. Because they're the best there is.
 

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Discussion Starter #17
I got this info early this morning from Jennifer Sichler at HK in Germany. She discussed my questions with a HK technician the following results are...

Muzzle Device = 60Nm
Castle nut = 60Nm
Grip screw = 3Nm
Handguard rail screw = 12Nm
 

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Discussion Starter #18
The handguard rail screw seems to be a bit high compared to the originally posted 7Nm. The 12Nm is near the breaking point! Maybe the A3 screws are stronger? Maybe an update?

Anyway this info was received this morning so it must be the "latest" I assume.
 

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The handguard rail screw seems to be a bit high compared to the originally posted 7Nm. The 12Nm is near the breaking point! Maybe the A3 screws are stronger? Maybe an update?

Anyway this info was received this morning so it must be the "latest" I assume.
The thing is, 7 Nm torque value is inscribed directly on the heads of new ("A3") hexagonal handguard rail locking screws. As for the flash hiders, 30 Nm torque value is inscribed directly on the 237803 / 211719 models. As per MR223 A3 Operator’s Manual, torque value for the 237016 flash hider is 60±5 Nm, whereas the MR308 A3 Operator’s Manual allows only for 45±5 Nm torque. Both above quoted manuals are available on their site (Heckler & Koch :: Operator Manuals). With all due respect to the girl, I wouldn't risk screwing up my handguard because one Jennifer didn't know any better.
 
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