Page 10 of 16 FirstFirst ... 89101112 ... LastLast
Results 91 to 100 of 151

Thread: Action spring pressure measurements.

  1. #91
    Join Date
    Nov 2010
    Location
    MI
    Posts
    3,055
    Feedback Score
    21 (100%)
    The 30-50 was a RAW number, neglecting the effect of the moveable weights.

    I did some quick drop tests.

    An H2 buffer dropped 20 inches onto concrete rebounded 4 inches.

    That's 20% NET return after the moveable weights damped the impact.


    Interestingly, the spring biased buffers (AKA A5) hardly rebounded at all.

    Quote Originally Posted by MarkG View Post
    I was only addressing the 30-50% energy return.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  2. #92
    Join Date
    Oct 2007
    Posts
    6,611
    Feedback Score
    11 (100%)
    Quote Originally Posted by Clint View Post
    The 30-50 was a RAW number, neglecting the effect of the moveable weights.

    I did some quick drop tests.

    An H2 buffer dropped 20 inches onto concrete rebounded 4 inches.

    That's 20% NET return after the moveable weights damped the impact.


    Interestingly, the spring biased buffers (AKA A5) hardly rebounded at all.
    When you dropped it the weights were out of play as they were sitting on the buffer end. When the action moves it, they are on the buffer face side due to inertia.

  3. #93
    Join Date
    Oct 2009
    Posts
    1,438
    Feedback Score
    12 (100%)
    Quote Originally Posted by WS6 View Post
    When you dropped it the weights were out of play as they were sitting on the buffer end. When the action moves it, they are on the buffer face side due to inertia.
    It was also missing 11.5 ounces of bolt group on top of that which is going to eat some of the energy.

  4. #94
    Join Date
    Apr 2009
    Location
    FL -Where it's summer 10.5 months out of the year
    Posts
    4,114
    Feedback Score
    17 (100%)
    Quote Originally Posted by Clint View Post
    The 30-50 was a RAW number, neglecting the effect of the moveable weights.

    I did some quick drop tests.

    An H2 buffer dropped 20 inches onto concrete rebounded 4 inches.

    That's 20% NET return after the moveable weights damped the impact.


    Interestingly, the spring biased buffers (AKA A5) hardly rebounded at all.
    Interesting.

    Sent from my SPH-L720T using Tapatalk
    "That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892

    "The body cannot go where the mind has not already been."

  5. #95
    Join Date
    Sep 2009
    Location
    NC
    Posts
    1,039
    Feedback Score
    8 (100%)
    Quote Originally Posted by Iraqgunz View Post
    You will notice that I acknowledged that a heavier buffer will fix the issue. Which is what we did temporarily. But the root cause (at least in my experience) was the enlarged port size.

    I may be wrong, about this, but as I understand it the U.S military has been using H2 buffers in their M4's for some time. I know that I saw some in fact with H2's in them.

    So in the cases where I dealt with this, the common link was porn star gas ports+full auto fire. As soon as I received the new barrels and re-barreled the weapons, the issues stopped. I am not an engineer or a rocket scientist, but when I take several carbines with this issue, and I do the exact same thing and I put the same springs and buffers back in the weapon and the only variable that changed was the barrel I have to logically conclude it was the problem.

    If I am wrong so be it.

    Sorry guys...been at work over night!


    I'm definitely not saying you're wrong; I agree with your thinking 99% of the time. What is becoming apparent to me, as evidenced by this thread, is that there are 2 vastly different solutions to this problem. I want to be clear that I do not think you are wrong!

    Have you had any experience with rifles of the non-shitty over gassed barrel variety exhibiting carrier bounce (maybe due to worn or underpowered buffer springs)?
    "An opinion solicited does not equal one freely voiced," Al Swearengen, Deadwood 1877.

  6. #96
    Join Date
    Apr 2009
    Location
    FL -Where it's summer 10.5 months out of the year
    Posts
    4,114
    Feedback Score
    17 (100%)
    I think, if we've established anything, it's that it is basically IMPOSSIBLE to completely sever/isolate the recoil stroke from the return-to-battery stroke in the recoil system with regard to bolt/carrier bounce.

    To that end, both IG and the others can be right at the same time.
    "That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892

    "The body cannot go where the mind has not already been."

  7. #97
    Join Date
    Sep 2009
    Location
    NC
    Posts
    1,039
    Feedback Score
    8 (100%)
    Ok I just got the 2 Tubb 36 coil CS flat wire springs and put them in with H buffers. From a quick bullet trap test (2 rounds not shouldered) they seem to run softer and a bit flatter (recoil impulse not as sharp), especially with my wife's rifle that is super light weight.

    I'll give them a workout in the next few weeks and report back!

    For the record, I think this thread has been intriguing and very informative as to the wide varieties of options, problems and various solutions!

    Thanks to all for that!
    "An opinion solicited does not equal one freely voiced," Al Swearengen, Deadwood 1877.

  8. #98
    Join Date
    Aug 2007
    Posts
    390
    Feedback Score
    3 (100%)
    There is another effect which can contribute to bolt bounce. When the bolt/carrier slams home there is a compression wave in the action spring. As the bolt closes the coils are all moving forward and they "pile up" when the bolt closes. This results in the spring being compressed. The wave then bounces back which reduces force on the carrier just as it is rebounding itself. High speed video of bolt bounce usually shows the bolt bouncing several times before it settles down as the wave in the spring bounces from one end to the other and dies out.

    If the buffer is heavy enough and if its weights slam forward at the right time then the bolt bounce is canceled to some degree. With a full auto weapon there is the possibility of resonance between the cycle rate and the natural frequency of the components. This can make the bolt bounce greater or less depending on if the frequencies interact constructively (one adding to the other) or destructively (one cancelling the other) .

    Hope this helps clarify a very complex combination of system interactions.
    Last edited by DBR; 05-13-14 at 01:09.

  9. #99
    Join Date
    Jun 2011
    Location
    Back where I belong
    Posts
    1,661
    Feedback Score
    2 (100%)
    Where did you get this? I want to quantify it. I have not heard of "piling up". It might explain some things.

    Not giving you shit, just wanting to expand the knowledge base.
    "You cannot play fair with people who don't care if you get wiped off the map. You don't have to hate everyone who isn't part of your tribe, but it is foolish to keep caring about people who don't care about you."
    Speech at the second National Policy Institute conference, December 26, 2013.



    See you soon, AC.

  10. #100
    Join Date
    Aug 2007
    Posts
    390
    Feedback Score
    3 (100%)
    You are right. The spring dynamics do at least partially explain the bolt bounce issue.

    Whenever any spring compresses or relaxes rapidly there is a rebound wave that travels along the length of the spring and rapidly decays. In short springs it is usually unnoticeable but as a spring gets longer it can be a problem. In industrial applications various types of dampers are used to control this action if it matters.

    I am a retired engineer and I have done consulting work involving shooting high speed video of AR15s and I have witnessed the "bolt bounce" phenomenon myself. This work is the property of my client and I cannot publish it.

    Not to long ago there were videos on M4 carbine which showed the bounce. If you do a search on Youtube for "bolt bounce" there are several videos that show the bolt's actions. For the reasons stated above I cannot demonstrate the spring actions but they are real.
    Last edited by DBR; 05-13-14 at 02:10.

Page 10 of 16 FirstFirst ... 89101112 ... LastLast

Bookmarks

Posting Permissions

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