[nsheers]

HKParts has HK416 OEM 10.4 vented gas blocks and HK416 A5 "style" extended castle nut

Just happened to be passing through HKParts and saw that they currently have in stock:

HK416 10.4 vented gas blocks (noted as HK OEM), which are a bit of a unicorn
HK416 10 Gas Block

and HK416 "style" A5 extended castle nuts (presumably not HK OEM)
HK416 A5 Extended Castle Nut

 

[Brad4065]

Well damn that was quick.

 

[nsheers]

With respect to the vented gas block, I received the one I ordered and it appears to be an OEM part with the expected "10" marked on the side. I compared the size of the vent and it appears identical to my BA and BC date coded 10.4 vented gas blocks, and visibly smaller than the standard vent on the 14.5/16.5. All in all, the vented gas blocks check out.

 

[HK23E]

Thanks nsheers. Do you think the vented block will fit on early 10.4 factory 416 barrel with the heavy profile?

 

[Player_To_Be_Named...]

Nathan - thanks for the head's up. I just ordered one for my older 10.4 upper!

 

[nsheers]

Thanks nsheers. Do you think the vented block will fit on early 10.4 factory 416 barrel with the heavy profile?

I do, as a matter of logic. (I haven't tried it.)
In the manuals, the gas blocks for the 10.4 inch barrels have maintained their HK part numbers throughout the transition from heavy to light profile (203587), while the barrels themselves changed (233103 to 233660). Both types of barrels are shown fitting the same gas block part number, so I'd expect a heavy profile barrel to fit these new gas blocks. Nothing about the vent itself changes its fitment to the barrel, it has the same dimensions as far as that is concerned.

 

[tlrgsxr]

FWIW, I'm using the standard 14.5"+ gas block like the one that comes stock on a Mr556 with the large vent hole on a 10.5" SBR and it's still overgassed with a suppressor and standard NATO ammo.

 

[dms16]

Thanks nsheers. Do you think the vented block will fit on early 10.4 factory 416 barrel with the heavy profile?

The dimensions under the gas block for the HK barrels are the same; foreward (M27) and rear (lightweight, MR556) is where they vary.

 

[RegularGuy461969]

I thought HK lopped off the sling ears when they drill the gas blocks to vent them?

 

[Brad4065]

With respect to the vented gas block, I received the one I ordered and it appears to be an OEM part with the expected "10" marked on the side. I compared the size of the vent and it appears identical to my BA and BC date coded 10.4 vented gas blocks, and visibly smaller than the standard vent on the 14.5/16.5. All in all, the vented gas blocks check out.

Nathan

{Ok....I'll go ahead and be the dumba$$ in the room......as usual.}

I thought these were heated and pressed on at the factory??? How difficult is it to replace ....say a standard block on an AI date coded upper with a new vented gas block? Before I start tearing apart my $5K upper.

 

[gopherboy128]

Those of you who have ordered one- can you post photos of what you received? HKParts uses the old 10.4" non-vented block for both product's photos.

Thanks.

 

[HK23E]

Brad, that was my question as well. However, after some research, the A5 block with the adjustable gas regulator is the gas block that is press fit and shrunk on the barrel. Every photograph I have found of the vented 10.4" gas block shows that it is pinned with the two roll pins like the earlier non-vented gas blocks. So unless there is some change in the internal dimensions of the gas block, the new style should fit on the barrel. When I get my block, I will post photographs compared to my old non-vented block as well as installed on one of my 10.4" heavy profile barrels. Fingers crossed!

 

[Brad4065]

Brad, that was my question as well. However, after some research, the A5 block with the adjustable gas regulator is the gas block that is press fit and shrunk on the barrel. Every photograph I have found of the vented 10.4" gas block shows that it is pinned with the two roll pins like the earlier non-vented gas blocks. So unless there is some change in the internal dimensions of the gas block, the new style should fit on the barrel. When I get my block, I will post photographs compared to my old non-vented block as well as installed on one of my 10.4" heavy profile barrels. Fingers crossed!

HK23E:

PLEASE DO!!!! Can you send me before and after pics? I'd love to know how that whole process plays out. I've got some beater 10.4" uppers, and I've got some that have never been fired....so I'd like to get it right on the beater, before I enter into the pristine collection. Thanks again.

 

[JNAP94]

With respect to the vented gas block, I received the one I ordered and it appears to be an OEM part with the expected "10" marked on the side. I compared the size of the vent and it appears identical to my BA and BC date coded 10.4 vented gas blocks, and visibly smaller than the standard vent on the 14.5/16.5. All in all, the vented gas blocks check out.

So you eyeballed thousandths of an inch? Or did you have a set of pin gauges on hand and measure it?

 

[JNAP94]

Brad, that was my question as well. However, after some research, the A5 block with the adjustable gas regulator is the gas block that is press fit and shrunk on the barrel. Every photograph I have found of the vented 10.4" gas block shows that it is pinned with the two roll pins like the earlier non-vented gas blocks. So unless there is some change in the internal dimensions of the gas block, the new style should fit on the barrel. When I get my block, I will post photographs compared to my old non-vented block as well as installed on one of my 10.4" heavy profile barrels. Fingers crossed!

Check the A3 barrels? There was never an HK part number for the Vented gas blocks. They were special order for certain Agencies and Units.

Not saying they couldn't have changed things, just curious to know facts.

 

[HK23E]

Jason, right now that is all I can do until I get the vented gas block in my hands. I decided it worth it to take flyer and pick one up and try it.

 

[JNAP94]

Jason, right now that is all I can do until I get the vented gas block in my hands. I decided it worth it to take flyer and pick one up and try it.

Not ment to be taken negatively towards you personally!! I am interested in seeing it as well, and having someone pin gauging the vent hole?

 

[HK23E]

Below is a link to one of members who has both vented and non-vented gas blocks on 10.4" uppers that he updated with photographs.

http://www.hkpro.com/forum/hk416-hk...e-rail-416-upper-finish-gas-block-pics-5.html

Personally, I have never handled one of the vented gas blocks, much less removed them from a barrel.

I have however, removed the non-vented gas block a 10.4" heavy barrel. I have also handled an A5 at shot show when they were first introduced and the photograph uploaded by James shows the difference in how is it retained.

http://www.hkpro.com/forum/teufelshund-tactical/202895-notes-hk416-armorer-course.html

As I posted, I believe the vented block will work. However, there is only way to way to know and this is try it. I am keeping my fingers crossed there is not some internal dimension differences that I can't see including gas port size on the barrel itself which frankly has been debated over and over.

 

[HK23E]

In the first link, Drooler pin gauged the vent holes on his gas blocks. If someone wants to loan me a set of the pin gauges, I am happy to do so with my barrel port and the vent hole on the gas block.

 

[nsheers]

As I noted above, I visually compared the vent holes. It was fairly easy to see the difference between the two sizes side-by-side, especially using light. The 14/1000s of an inch difference is pretty noticeable when it makes up approximately a third of the total size. I also was able to slide a 0.050 wrench, my smallest one, down the full size 16.5 vent hole, but I was not able to get any of it into the 10.4 vent hole, either on the new HKParts gas block, or on my vented BA and BC 10.4 inch uppers. I don't have pin gauges to measure the holes precisely, but the new vented gas block looks just like the ones on my BA and BC uppers, and has a vent hole approximately the same size, and certainly smaller than the full size vent. Since we know somebody commissioned the specially vented 10.4 inch gas blocks with smaller holes (and I was involved in the discussion referenced above from a couple of years ago), that information was enough for me to conclude it was worth a try to switch the gas blocks out, but to each his own.

As for the A5 gas blocks, they are indeed the ones that are shrunk onto the barrel as an integral unit. They no longer have a separate part number as someone noted above, just the gas nozzle and regulator parts do, but I don't know anyone who sells them. Maybe in Canada? I'm also not aware of the vented 10.4 inch gas blocks having a unique part number either.