Anyone have a KDF Brake?

Discussion in 'Equipment Discussions' started by Tim Behle, Jul 7, 2003.

  1. Tim Behle

    Tim Behle Well-Known Member

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    I recently had a new rifle built, complete with a KDF brake. It's the first rifle I have ever owned with a muzzle brake.

    After reading Jake's thread the other day, and of the troubles he has had. I got to wondering about my own brake.

    So I spun it off and looked at it. I didn't see anything out of the ordinary. Just a little powder fouling. So I dropped a 200 MK into it, and it got stuck. I tried a different one, same results. I tried some 220 MK, then some Nosler Partitions. All had the same result, none would pass thought the brake. I cleaned it with a brush and solvent, and tried it again, no luck. I measured the inside, the calipers read .3065". Maybe I measured it wrong, but I got the same reading at different angles, several times.

    So I called the gunsmith, he said send it back and he would make it right.

    No problem, I'm a firm believer that in spite of our best intentions, sometimes bad stuff happens. Not wanting to damage anyone's reputation, due to an honest mistake, I kept quiet and sent it off.

    Then just 10 minutes ago, he called me back. Says there is nothing wrong with the brake, but he would be happy to bore it out to the next larger size. I was told I must have been trying to put the bullet in at an angle, and not straight.

    Am I nuts? Shouldn't a bullet that measures .3080" pass though a hole that is supposed to be .3240?

    Can someone who has one of these brakes, try dropping a bullet trough it and let me know if it fits?
     
  2. ewallace

    ewallace Well-Known Member

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    I don't have a KDF brake but I just went and dropped a bullet threw my brake that S1 built for me and the bullet has plenty of room then I did the same with the brake that Dave Tooley did and had the same results.
    Crow Mag
     

  3. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Tim

    I'll take my KDF off one of my 300 Weatherbys and see what happens.

    Later
    DC
     
  4. Guest

    Guest Guest

    The funny thing is, you do not need to make the hole a super tight fit to make the brake more effective. A lot of guys try to make up for a ineffective brake design by making the exit hole as small as possible.

    .030" over bullet diameter works just fine.

    Even the experts that run flow benches for racing heads do not measure flow until the valve is at least .040" off the seat.

    Anyone ever looked at cam shaft specs? Notice that the duration spec does not begin until a specific amount lift is achieved.

    Anyone see a pattern developing?

    The physical laws that govern supersonic gas flow are different than the laws of fluid dynamics that apply to your lawyers Hobie Cat.
     
  5. Darryl Cassel

    Darryl Cassel Well-Known Member

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    Tim

    The bullet has plenty of room dropping through my KDF brakes.

    Later
    DC
     
  6. Darryl Cassel

    Darryl Cassel Well-Known Member

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    S1

    The "Holland Brake" instruction sheet calls for a hole to be .020" over bullet diameter.

    Have you noticed any difference between bullet clearance of say .016" up to .030" in "felt recoil"??

    Would say a 020" clearace give better dampening effects over a .030"??

    Jusat wonderimg as I have not had one that was .030" over bullet diameter.

    Later
    DC
     
  7. Tim Behle

    Tim Behle Well-Known Member

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    Thanks DC,

    I don't know why he decided to tell me there was nothing wrong with the brake, But I sure couldn't get a bullet to pass all of the way though it.

    Tim
     
  8. Guest

    Guest Guest

    DC... We built a recoil sled years ago to test different brake designs. We videoed each design, and had a tell tale on the sled. That was when we noticed how much torque was involved in recoil. We tested many different designs, and also tested the same design at different exit diameters from .007" clearance up to .060" Our sled which could easily differentiate between different brake designs could not measure the difference in recoil reduction between a .007" hole and a .050" hole on the same brake, of a good design.

    .020 will work fine as long as you do not have a bunch of edges with surfaces 90 degrees to the bore line, and your brake material is above 30 rockwell on the C scale.

    [ 07-08-2003: Message edited by: S1 ]
     
  9. Darryl Cassel

    Darryl Cassel Well-Known Member

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    S1

    Thanks for the info.


    Tim

    It will go through now.

    DC

    [ 07-08-2003: Message edited by: Darryl Cassel ]
     
  10. H-BAR

    H-BAR Well-Known Member

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    KDF breaks to my knowledge all come with a small hole that needs to be sized accordingly if the breaks hole was too small it was the gunsmiths fault!!! I have one on my 25-06 and it seems to work very well. If the gunsmith does his work properly you don't need a monster hole. A big hole is only a bandaid for sloppy setup work!!! By the way I saw a KDF break that a guy did himself and forgot to ream the hole to proper size. The 30 cal bullet tore the end off of the break. Any burrs on these breaks are a combination of sloppy machining and then having a guy that owns it shoving something through the holes in to take it off pushing the burr back into the path of the bullet. KDF breaks=seeing red mist!!!
     
  11. H-BAR

    H-BAR Well-Known Member

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    Oh I forgot it drops through!!! Don't let the smith charge you as it was his error and he was lucky as you were that no damage was incurred.
     
  12. Guest

    Guest Guest

    H-Bar ...The size of the hole is not necessarily corellated to the "Quality of the Machine Work". It is however corellated to the accuracy achieved. It is also true that if you do not have coaxial alignment of the bore when boring the final diameter of the brake, you would have to make it larger than needed to keep the bullet from scraping the brake.

    KDF makes a mediocre brake, no better than the New Holland. The recoil reduction is driven by the brake designer, the ultimate accuracy is determined by the installer of the brake.
     
  13. Hunter66654

    Hunter66654 Well-Known Member

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    S1, you seem to be very knowledgible on different breaks. I have been looking for a break that does not increase the noise. BP-TEC claims to make such a break. On their web site www.bp-tec.com , their first page says " no additional noise ". Are you familiar with this break, and if not would you look at the info on their site and offer your comments. They have gone so for as to say they would refund the money if the noise is greater.
     
  14. Guest

    Guest Guest

    I just tried the KDF on the "other" Tomahawk I have, also built by Ray Romain. It is identical to the one I sold Jake, except it it SS instead of CM. It is a very tight fit with a 240SMK, but as long as it is straight, the bullet slides thru without any interference.