Page 4 of 4 FirstFirst ... 234
Results 46 to 52 of 52

Thread: Does barrel straightness effect accuracy.

  1. #46
    Join Date
    Aug 2007
    Location
    Kansas
    Posts
    215
    Six or seven years ago I took 3 what was good shooting rifle barrels now shot out from 3 different top barrel makers. Marked a straight line on the outside of each barrel then cut them into four inch lengths. What I found was they all had more than one curve, donít really remember the numbers in thousands of the bow of the curves. That is why from that day forward I always indicated both the Chamber end and the Muzzle end 2.5 to 3 plus inches into the bore as I cut them and let the other end go wild. I want the Throat and Chamber along with the Crown to be as straight to the Bore as I can get them.

    One time I cut the muzzle end off 5 or 6 inches to crown the new chambered barrel and found the bore was off center too much and called the maker they sent me a new barrel and said two trash the bad barrel.
    Note: This was a light weight barrel around .650 at the finished crown and it showed up in the finish crown.

    Chet

  2. #47
    Join Date
    Jul 2005
    Posts
    376
    Quote Originally Posted by coyotechet View Post
    Six or seven years ago I took 3 what was good shooting rifle barrels now shot out from 3 different top barrel makers. Marked a straight line on the outside of each barrel then cut them into four inch lengths. What I found was they all had more than one curve, donít really remember the numbers in thousands of the bow of the curves. That is why from that day forward I always indicated both the Chamber end and the Muzzle end 2.5 to 3 plus inches into the bore as I cut them and let the other end go wild. I want the Throat and Chamber along with the Crown to be as straight to the Bore as I can get them.

    One time I cut the muzzle end off 5 or 6 inches to crown the new chambered barrel and found the bore was off center too much and called the maker they sent me a new barrel and said two trash the bad barrel.
    Note: This was a light weight barrel around .650 at the finished crown and it showed up in the finish crown.

    Chet
    Barrel drilling is not exactly a rigidly guided thing.

    The actual drill is the diameter of the hole and a long thin piece of drill rod in most cases.

    You can easily flex a length of drill rod .20 in in diameter and 30 inches long.

    The slightest variation in the material being removed will put a sideways load on that long bit and it WILL flex.
    That is the reasoning behind my comment that a straight hole is more likely from very uniform material.

    And to add to that we add things to the metal (like sulfur in stainless) to make chips from machining the material
    break off in smaller pieces.

    Otherwise stainless is a very 'gummy' material and sticks to cutters and makes long chips.
    They will not clear in the narrow passages available in a 'gun drill' bit for them to exit from the cutting 'face' way
    down in that hole through the narrow flute in the side of the bit.

  3. #48
    Join Date
    Feb 2007
    Location
    Mattoon
    Posts
    3,139
    mike is right about point of impact being close while putting the muzzle in front of the chamber. For me though, thats small potatoes. It doesnt take any effort to make an adjustment with the scope. I make my adjustments while breaking the barrel in. Even with the Gordy method, if you clock the bore to 6 or 12, your never more than an inch or so out anyway. Im not going to say one method is better than the other. In my mind though, we know the bore isnt straight, so why in the world would i indicate 20 something inches away from the work? I cant personally picture that. Stubborn maybe?? Lots of good shooting barrels chambered both ways, thats for sure. Lee

  4. #49
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
    Posts
    5,662

    I indicate both ends

    Quote Originally Posted by skeetlee View Post
    mike is right about point of impact being close while putting the muzzle in front of the chamber. For me though, thats small potatoes. It doesnt take any effort to make an adjustment with the scope. I make my adjustments while breaking the barrel in. Even with the Gordy method, if you clock the bore to 6 or 12, your never more than an inch or so out anyway. Im not going to say one method is better than the other. In my mind though, we know the bore isnt straight, so why in the world would i indicate 20 something inches away from the work? I cant personally picture that. Stubborn maybe?? Lots of good shooting barrels chambered both ways, thats for sure. Lee
    mainly so the muzzle end wont try to whip out of balance. I have a spider back there and just keep it close to being concentric but not to the degree I do the chamber end. Of course I only do one or two barrels a year sooooooooo.

    Pete

  5. #50
    Join Date
    Feb 2003
    Location
    Texas Panhandle
    Posts
    1,842
    Quote Originally Posted by skeetlee View Post
    mike is right about point of impact being close while putting the muzzle in front of the chamber. For me though, thats small potatoes. It doesnt take any effort to make an adjustment with the scope. I make my adjustments while breaking the barrel in. Even with the Gordy method, if you clock the bore to 6 or 12, your never more than an inch or so out anyway. Im not going to say one method is better than the other. In my mind though, we know the bore isnt straight, so why in the world would i indicate 20 something inches away from the work? I cant personally picture that. Stubborn maybe?? Lots of good shooting barrels chambered both ways, thats for sure. Lee
    Lee, Iím not saying one way is better or worse than another. I just havenít seen that it makes a difference which method that is used as to how the barrels shoots when we are done between the way I use and yours. I think a lot of what we do is in our heads. I think as long as the freebore is centered in the bore when weíre done, the barrel has as good a chance of shooting to match winning capability as another one indicated in by another method that also has its freebore in the center of the bore. I think itís real easy to overthink chambering barrels. We are so used to indicating in to as close to zero runout as we can get, that we forget as to what tolerances we are using. What we all want to do is to have barrels that wonít shoot be very very few and very very far between. What I have found over the years is that there are lots of ways to get to the result that we want. Iíve always recommended that people use what method works for them. Itís one case where one way isnít right and another wrong, just different.

  6. #51
    Join Date
    Feb 2003
    Location
    Tennessee
    Posts
    6,365
    Quote Originally Posted by Mike Bryant View Post
    ......works for them. Itís one case where one way isnít right and another wrong, just different.

    Yep, that is the truth!!!

    /

  7. #52
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
    Posts
    5,662

    I had an interesting thing happen the other day

    I had an old cull barrel from a previous rifle and decided to set it back for a rifle with a different tenon thread. Had the room to do it. I dialed the barrel in to where I had .000" with a .0005" Best Test indicator on a straight pin that fit the hole well.

    I noticed the screw that holds the bushing on the reamer seemed on the skinny head size but seemed to hold the bushing on fine by finger feel, at least. On the third retraction of the reamer I noticed the bushing was not present on the reamer. Upon investigation, I found it wedged in the bore.

    I went to the next smaller bushing and proceeded to finish the chamber. When I had finished and had blown the oil out of the barrel. I borescoped the chamber area and found that I had cut two lands down noticeably more than the others, both side by each!

    My conclusion here is that I found a crook in the bore, that is sometimes spoken of and that the lands that were cut more were proud in the crook.

    Am I way out in left field here ? I had a barrel in the past done by a Smith of some note that looked similar. The barrel shot OK but wasn't a hummer by any stretch.

    Pete

Posting Permissions

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