Page 1 of 2 12 LastLast
Results 1 to 15 of 17

Thread: Equation for tuning

  1. #1
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537

    Equation for tuning

    Okay, lets see how you calculate to determine the additional weight needed as a starting point in tuning a new barrel.
    Bare barrel shoots 3/4 inch vertical with best ammo.
    Barrel = Shilen Octagon, 25 3/4" bore .221"
    Diameter at muzzle, .875
    Dead spot determined by tapping the barrel and listening for the dead spot = 5.5" from crown.
    Tuner = Harrell total weight 8 oz. Threaded for additional weights.

  2. #2
    Join Date
    Jul 2008
    Location
    MD eastern shore
    Posts
    922
    Fred: Set the tuner at 165 plus or minus. bob

  3. #3
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Okay, Bob, how did you determine that? Your saying, the Harrel Tuner @ 8 oz is suffient?
    Last edited by Fred J; 05-23-2012 at 02:23 PM.

  4. #4
    Join Date
    Jul 2008
    Location
    MD eastern shore
    Posts
    922
    Fred: I plagiarized it from another forum. Actually tho I have 2 barrels that come real close to your description, one tunes at 159, the other at 168. No extra weight but adding a Harrels bloop requires only a few clicks if any.....and the bloop weighs 2.0 ounces. bob

  5. #5
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Thanks Bob. I'll try that.

  6. #6
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
    Posts
    6,206
    Years ago, Hoke Kerns wrote an article for PS magazine titled "In 185 I do believe". I collaborated with him in the teting for that article and was given credit for it by him in the text of the article.

    Having said that, my 10.5 rifle has a Harrels' tuner on it and it shoots tiny round holes @ 20 and 50. With the Noodle I have on it now, it likes #55 for one lot, # 57 for another and #20 for the third.

    My summation is the rifle is probably not in tune; certainly not as BC discribes a Stopped Muzzle. I suspect the real tune is with more weight on the tuner but I am not willing to expend the limited good ammo I have for the rifle to find out.
    Last edited by Pete Wass; 05-23-2012 at 09:43 PM.

  7. #7
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    This appears to be my problem as well. Not tuner setting will repeat. I've also tried Hoke's suggestion, but didn't feel it was getting the most out of this barrel.

  8. #8
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Still looking for the correct formula.

  9. #9
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Shot the worst in a long time. Still waiting on the formula that will get me closer to a starting point.

  10. #10
    Join Date
    Aug 2005
    Posts
    820
    Hopwell method, I suppose you could start out with some lesser quality but nearly the same speed ammo to get close, then the good stuff for a finale. Make sure your bedding is good before starting, otherwise you will be chasing your tail.

  11. #11
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Tried that and still can't get it close enough to repeat. Beddings good, chamber is very good & bore slugs extremely round with slight taper. Dead spot is 5.5 in from the muzzle. What I am asking, is how do I calculate the amount of weight in ounces, I need to place in front of the muzzle? How is that calculated? I've tried the formulas on the Lilja site but it hasn't provided an accurate answer.

  12. #12
    Join Date
    Feb 2011
    Location
    Plymouth, MI
    Posts
    52
    Quote Originally Posted by Fred J View Post
    Tried that and still can't get it close enough to repeat. Beddings good, chamber is very good & bore slugs extremely round with slight taper. Dead spot is 5.5 in from the muzzle. What I am asking, is how do I calculate the amount of weight in ounces, I need to place in front of the muzzle? How is that calculated? I've tried the formulas on the Lilja site but it hasn't provided an accurate answer.
    Fred try this...

    Barrel dia. of .875 less .221 bore is .654 Dia of solid metal...

    use formula Dia squared x 2.67 to arrive at lbs/ft...

    .654x.654=.4277x2.67=1.141 lbs/ft...

    1.141lbs/ft x 16oz/lb = 18.256 oz/ft / 12"/ft= 1.52 oz/inch...

    5.5" from Node center to muzzle end = 5.5" x 1.52 oz/" = 8.36 oz...

    Calfee says 1 1/2 times that weight for a total of 8.36 oz x 1.5 = 12.54 oz...

    Calfee says place that weight (12.54oz) 1 1/2 times the distance of Node center to muzzle end or 5.5" x 1.5 = 8.25inches from muzzle...

    So per Calfee explanation place 12.54 oz at 8.25 " from the end of your barrel muzzle for a "Stopped" barrel...

    I think my numbers are correct but please check me out before using...

    Hope the info helps

    PS...Calfee rings his barrels out of the actions, naked barrel...and is usually between 2" and 3" from Muzzle end to Node center...FWIW
    Last edited by Bolero; 06-03-2012 at 07:12 AM. Reason: Clarification

  13. #13
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Bolero:
    I found a small section of barrel that is similar in diameter ( .8775" by 1.5685" in length. Bore is .2265". Using your formulas, I get a total weight of 2.3656908 ounces. Using a postage scale, it actually weighs 4 ounces. Why the difference of 1.634309 ounces? Could the type of steel be the difference? Not sure what type is.
    Fred J

  14. #14
    Join Date
    Feb 2011
    Location
    Plymouth, MI
    Posts
    52
    Fred, yes the type of steel makes a difference, stainless is heavier than carbon steel...

    The info I posted will get you pretty close...

    are you trying to use the Calfee method to find the best place to put your tuner...???

  15. #15
    Join Date
    Feb 2003
    Location
    San Antonio, Texas
    Posts
    2,537
    Not really. Right now, trying to determine how much in length, I can remove from a barrel to make weight. Measure twicw, cut once.

Posting Permissions

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