Buffer options for 10.4
Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 28
Like Tree1Likes

Thread: Buffer options for 10.4

  1. #1
    Junior Member

    Join Date : Mar 2012
    Posts : 39
    Mentioned
    2 Post(s)

    Default Buffer options for 10.4

    Currently running a geissele spring and buffer on a vented 10.4. It's pretty violent. It's ejecting a neat pile of brass at 5 o'clock with significant muzzle jump. Anyone know what the hk416 buffer weight is? And a suitable replacement?

  2. #2
    HKPRO Professional
    LCSO264's Avatar
    Join Date : Feb 2005
    Location : Northwest
    Age : 44
    Posts : 3,672
    Mentioned
    13 Post(s)

    Default

    I don’t know the weight off hand, but the general consensus it that you should just run an HK spring and buffer
    HK91
    HK94
    USC/UMP
    SL8/G36
    P7M8
    P9s .45acp
    VP70Z
    USP Tactical .45acp
    V51/HK51 clone
    HK45
    HK45c
    HK 416 10.5" upper
    GSG5PK
    P30Ls
    HK45T (OD Green)
    VP9
    CR556A1
    P30SKs
    SP5K

  3. #3
    Very Senior Member
    InshallahTech's Avatar
    Join Date : Aug 2013
    Location : WA
    Posts : 389
    Mentioned
    15 Post(s)

    Default

    Firstly, let's establish where you think "5 o'clock" actually is.

    By accepted OPV standards, a 5 o'clock ejection (very far to the rear) means the gun isn't cycling properly with extremely weak ejection caused by slow bolt speeds. Pretty much anything past 4:30 means weak cycle or no cycle and eventually not locking back on the final round of the magazine (by USGI standards only).

    Especially with the factory ejector spring installed. Considering that the HK factory ejector spring is slightly weaker than a USGI spring and allow ejection to be further forward with similar bolt speeds, ejecting that far to the rear means things aren't working correctly and the recoil/muzzle jump you feel is normal for a near bolt action gun.

    Basics are as follows:

    Slow bolt speed or stronger ejection spring = ejector pushes spent brass out of the ejection port quicker and the brass ejects further rearward as it can almost bypass the brass deflector entirely.

    Fast bolt speed or weak ejector spring means the bolt travels further rearward before the spent brass exits the ejection port and impacts the brass deflector which causes the brass to eject further forward depending on the actual bolt speed.

    Weak gas = slower bolt = rear ward ejection (3:30 to 4:30 and anything more then 4:30 needing maintenance)). Appropriate gas = proper bolt speed = side ejection (2:30 to 3:30). Excessive gas = fast bolt = forward ejection (2:30 or less with 2:00 to 1:00 being excessive and in need of maintenance).

    All of that is assuming USGI ejection spring. Those numbers need to be modified by adding + :30-ish when running the HK ejector spring.

    This is why it's not good for people to assume that the ejection pattern "chart" applies to all AR variants. It doesn't.
    Last edited by InshallahTech; 11-12-2018 at 12:19 AM.
    waylon43 likes this.

  4. Remove Advertisements
    HKPro.com
    Advertisements
     

  5. #4
    Very Senior Member
    IsaacL's Avatar
    Join Date : Feb 2011
    Posts : 258
    Mentioned
    8 Post(s)

    Default

    In short...

    You need to run the HK buffer/spring the way HK intended. 416's are NOT AR-15's.

    What did you expect to happen?
    Last edited by IsaacL; 11-11-2018 at 11:42 PM.
    On ne voit bien qu'avec le cœur. L'essentiel est invisible pour les yeux.

  6. #5
    Very Senior Member
    Machinegunleslie's Avatar
    Join Date : May 2017
    Location : Sunny & Warm Sarasota Florida
    Posts : 227
    Mentioned
    2 Post(s)

    Default

    I don't know alot about the HK ar platform but a shooting friend has probably put around 500 rds down range with his
    HK upper with a cut down10.5" barrel ( gas port on barrel opened up to .062 ) & adjustable gas block from HK Parts on my M16 lower (H2 buffer) (Semi/full auto/supressed/unsuspressed flawlessly ) Ejection between 2:00 and 3:00. I just asked him and he said his gas block is full open.
    Last edited by Machinegunleslie; 11-15-2018 at 05:50 AM.

  7. #6
    Very Senior Member
    InshallahTech's Avatar
    Join Date : Aug 2013
    Location : WA
    Posts : 389
    Mentioned
    15 Post(s)

    Default

    When HK released a vented gas block for the 10.4" barrels, the specification also called for the barrels gas port to be enlarged.

    If the gas block was replaced and the barrel gas port not opened, then the gun is naturally undergassed and allows use of weaker action spring and lighter buffer.

    Sure the gun will run and exhibit all the proper function indicators, but running the system like this without the heavier HK buffer and stronger HK spring also reduces some of the systems inherent reliability under harsh conditions. It will make the gun last longer though as bolt speeds are slower on the return /loading phase of the cycle of operation. Less wear on the internals, so there is a benefit to running it this way.

    That being said, you might as well be running a DI gun unless this gun is kept for show-and-tell.

  8. #7
    Member

    Join Date : May 2011
    Location : Roanoke, VA
    Posts : 50
    Mentioned
    0 Post(s)

    Default

    Maybe a silly question but when talking about the heavier HK buffer and HK spring is that the same as the MR556 buffer and spring? I've got an MR556 with a 10.4" barrel from HK parts and haven't shot it a lot but so far have not had any issues.

  9. #8
    Junior Member
    jmes731's Avatar
    Join Date : Sep 2017
    Location : Texas
    Posts : 27
    Mentioned
    1 Post(s)

    Default

    Quote Originally Posted by InshallahTech View Post
    When HK released a vented gas block for the 10.4" barrels, the specification also called for the barrels gas port to be enlarged.

    If the gas block was replaced and the barrel gas port not opened, then the gun is naturally undergassed and allows use of weaker action spring and lighter buffer.

    Sure the gun will run and exhibit all the proper function indicators, but running the system like this without the heavier HK buffer and stronger HK spring also reduces some of the systems inherent reliability under harsh conditions. It will make the gun last longer though as bolt speeds are slower on the return /loading phase of the cycle of operation. Less wear on the internals, so there is a benefit to running it this way.

    That being said, you might as well be running a DI gun unless this gun is kept for show-and-tell.
    So if someone were to cut down an mr556 upper to 10.4, then whomever installs the 10.4 GB would need to change the barrel gas port as well? And if so does it matter if the GB is vented or not?
    All empires are created of blood and fire.

  10. #9
    Junior Member

    Join Date : Mar 2012
    Posts : 39
    Mentioned
    2 Post(s)

    Default

    I had mine opened up a little at a time until it ran right.


  11. #10
    Very Senior Member
    InshallahTech's Avatar
    Join Date : Aug 2013
    Location : WA
    Posts : 389
    Mentioned
    15 Post(s)

    Default

    Quote Originally Posted by jmes731 View Post
    So if someone were to cut down an mr556 upper to 10.4, then whomever installs the 10.4 GB would need to change the barrel gas port as well? And if so does it matter if the GB is vented or not?
    Yes and yes.

    Some people don't know that the 10.4 barrels with vented blocks have larger gas ports so when they modify a 16 down to 10.4 and install a new 10.4 vented gas block, they don't do the port and wonder why things don't work with the factory HK buffer and spring.

    Switching to a USGI buffer and spring seems to be a really good way to account for this without changing the gas port.

Page 1 of 3 1 2 3 LastLast

Sponsored Links

 
 

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •