Berger 6.5 140 bullet length varies



  • I've been loading 6.5CM a short time. I have a Forster Ultra micrometer seating die. I noticed LOA measurement varied by as much as 008 with the same depth setting on the die. I'm wondering if the taper of the bullets are consistent?

    I measured 5 6.5 140 target hybrids and the bullets varied from 1.410" to 1.418"... Is this normal?..

    Not sure one issue has anything to do with the other.



  • Length to the tip or length to the ogive? .008" would not be atypical to the tip, however, that would be a lot between ogives.

    Length of your loaded round can easily vary that much to the ogive depending on the condition of your case necks.



  • I measured the bullet length over all not to ogive. I took the Forster ultra micrometer seating die apart and I looked where the seating die makes contact the 140 Berger hybrid at the bottom of tge seating stem. The bottom of the seating stem makes contact with the bullet about a half inch down from the tip of the bullet, but still about a quarter inch ahead of what appears to be the ogive. I'm deducing that the difference in length of the bullet is not at the point of contact with the die but somewhere along the half inch In front of where the bullet contacts the bottom of the seating stem. This seems to explain why the loaded bullet's LOA variance coincides with the length of the bullets themselves.



  • @martino1 said:

    I'm deducing that the difference in length of the bullet is not at the point of contact with the die but somewhere along the half inch In front of where the bullet contacts the bottom of the seating stem. This seems to explain why the loaded bullet's LOA variance coincides with the length of the bullets themselves.

    Agreed, most likely the difference in the shape and formation of the very tip of the bullet.



  • This is some serious stuff here. Even the polymer tipped projectiles length will vary unless you come across one that is in pristine condition. Lead tipped spire points are a guess. I made a makeshift trimmer but I don't shoot long range or have a precision bench rest rifle to apply this to either. I just did it for the heck of it.



  • I was concerned that the variability in the bullet length of the bullet I using translated into variability of the ogive to base consistency of the loaded round. BTW I just got my 6.5MM bullet comparator so I can actually measure base to ogive length.

    Before I took the seating die apart, I was expecting to see a small cup at the base of the seating stem where the bullet makes contact. Its more of tube that takes in the bullet in to about a quarter inch from the ogive. So long as the manufacturing variances are in front of the point of contact on the seating stem(towards the tip of the bullet), ogive to base should remain consistent.

    I don't know that I want start trimming meplats. I keep thinking about the aerodynamics of the open end of a cup. Even a small one.



  • @martino1
    I guess I was in the same boat you were in, I just recently got a 6.5 insert as well. I load for .260 Remington and 6.5x55 Swede and always measured over all length and set the seater die and forgot about it. Most of my handloads are for hunting so it wasn't a big deal, mainly want them to chamber and feed correctly.These new low drag projectiles might not work in some of the older low end seat dies being the seater plugs were made for more blunt projectiles. I have seen where some manufacturers offer replacement plugs for the more slender pills.



  • I measured 10 6.5 Berger target hybrids from the base of the bullet to the ogive using an RCBS dial caliper and a Sinclair 6.5mm comparator on a Hornady base. 8 bullets measured .674, 1 measured .6745 and 1 measured .675. Accuracy of the caliper according to RCBS is .001. I feel better about the ogive being where it's supposed to be using the Forster micrometer seating dies.



  • @martino1
    You probably have been here before but it sure is nice to have information like this. I wish I could find the dimensions for the other bullet manufacturers, maybe I don't know where to look.
    http://www.bergerbullets.com/pdf/Quick-Reference-Sheets.pdf



  • @bigfoot said:

    @martino1
    You probably have been here before but it sure is nice to have information like this. I wish I could find the dimensions for the other bullet manufacturers, maybe I don't know where to look.
    http://www.bergerbullets.com/pdf/Quick-Reference-Sheets.pdf

    I've got to look at the part number on the box I have when I get back from work because the chart that comes up on the link has a base to ogive for the 6.5 140 hybrid target at .704. PN 26414. The 6.5 140 long range BT Target has a base to ogive of .673 PN 26409 which is closer to what I measured.



  • @martino1 said:

    @bigfoot said:

    @martino1
    You probably have been here before but it sure is nice to have information like this. I wish I could find the dimensions for the other bullet manufacturers, maybe I don't know where to look.
    http://www.bergerbullets.com/pdf/Quick-Reference-Sheets.pdf

    I've got to look at the part number on the box I have when I get back from work because the chart that comes up on the link has a base to ogive for the 6.5 140 hybrid target at .704. PN 26414. The 6.5 140 long range BT Target has a base to ogive of .673 PN 26409 which is closer to what I measured.

    Your ogive measurement is not going to be the same as theirs with the Hornady tool. You'd have to know at what diameter on the bullet they measure that length to. The reference sheets are just that - a reference from one bullet to another in their lineup.



  • @tscustoms
    Yep, the Hornady insert for .264 measures .250.



  • @tscustoms said:

    @martino1 said:

    @bigfoot said:

    @martino1
    You probably have been here before but it sure is nice to have information like this. I wish I could find the dimensions for the other bullet manufacturers, maybe I don't know where to look.
    http://www.bergerbullets.com/pdf/Quick-Reference-Sheets.pdf

    I've got to look at the part number on the box I have when I get back from work because the chart that comes up on the link has a base to ogive for the 6.5 140 hybrid target at .704. PN 26414. The 6.5 140 long range BT Target has a base to ogive of .673 PN 26409 which is closer to what I measured.

    Your ogive measurement is not going to be the same as theirs with the Hornady tool. You'd have to know at what diameter on the bullet they measure that length to. The reference sheets are just that - a reference from one bullet to another in their lineup.

    I just used the Hornady base with the Sinclair 6.5 mm insert. I measured the base and insert with no bullet. I backed out empty measurement from the bullet in the caliper measurement. Why would this approach yield and incorrect measurement?

    Interesting that the Berger table I looked at had a SN 26414 for 6.5mm 140 gr Hybrid Target. I have 2 boxes of bullets that have the same discription except the SN is 26714. My bullet measures differently base to ogive compared to big foots table link.



  • @martino1 said:

    I just used the Hornady base with the Sinclair 6.5 mm insert. I measured the base and insert with no bullet. I backed out empty measurement from the bullet in the caliper measurement. Why would this approach yield and incorrect measurement?

    Because you're not necessarily measuring to the same inscribed(imaginary) diameter along the length of the bullet as they are.
    If they are measuring to an inscribed diameter or datum diameter along the bullet of say .256" (where the bullet would measure .256" in diameter) and your Sinclair insert diameter measures .260", you would get a shorter length than they do.



  • @tscustoms said:

    @martino1 said:

    I just used the Hornady base with the Sinclair 6.5 mm insert. I measured the base and insert with no bullet. I backed out empty measurement from the bullet in the caliper measurement. Why would this approach yield and incorrect measurement?

    Because you're not necessarily measuring to the same inscribed(imaginary) diameter along the length of the bullet as they are.
    If they are measuring to an inscribed diameter or datum diameter along the bullet of say .256" (where the bullet would measure .256" in diameter) and your Sinclair insert diameter measures .260", you would get a shorter length than they do.

    I expected more consistency in bullet measurement from the industry and especially a higher end bullet maker. I suppose no one sat down and said this is how we should do it industry wide.



  • @martino1 said:

    I measured 10 6.5 Berger target hybrids from the base of the bullet to the ogive using an RCBS dial caliper and a Sinclair 6.5mm comparator on a Hornady base. 8 bullets measured .674, 1 measured .6745 and 1 measured .675. Accuracy of the caliper according to RCBS is .001. I feel better about the ogive being where it's supposed to be using the Forster micrometer seating dies.

    And, right there is where you find out that you are wasting your time. Your caliper is not capable of distinguishing .674/.675 as different. In fact, the last significant digit of its measurement is 0.01". Measuring thousandths requires a micrometer calibrated against a reference block and marked to tenths of a thousandth. Then you subtract off the proportionate error between 0.0000 and 1.0000" which you have to hope is a constant error in the threads and not a point error.

    The base of the bullet is where the steering takes place, meplat uniformity does cause precession but the mass is very slight and nearly everything involved with getting the bullet from the factory to the target has magnitude of measurement larger effect on precision. If it were not so premium bullet manufacturers would fuss over it.

    Timin' has a lot to do with the outcome of a rain dance.

    0


  • @martino1 said:

    @tscustoms said:

    @martino1 said:

    I just used the Hornady base with the Sinclair 6.5 mm insert. I measured the base and insert with no bullet. I backed out empty measurement from the bullet in the caliper measurement. Why would this approach yield and incorrect measurement?

    Because you're not necessarily measuring to the same inscribed(imaginary) diameter along the length of the bullet as they are.
    If they are measuring to an inscribed diameter or datum diameter along the bullet of say .256" (where the bullet would measure .256" in diameter) and your Sinclair insert diameter measures .260", you would get a shorter length than they do.

    I expected more consistency in bullet measurement from the industry and especially a higher end bullet maker. I suppose no one sat down and said this is how we should do it industry wide.

    Its not the high end bullet maker. Its the low end tool your using. I'm not saying that a Hornady or Sinclair is crap, but for $30 your not getting a precision tool ground to exact specs. Thats what @tscustoms is saying. Your tool is a good refrence tool for you. You can't compare your measurement to anyone else's even on the same bullet you may get two different readings.



  • Here I thought I was doing good by getting the Sinclair bullet comparator and putting it in the Hornady base. Sux thinking you've got something dialed in and you don't. Grrrr



  • Don't sweat the small stuff. Use a seating plug that doesn't mess up the bullet tip and seat your bullets just deep enough to feed from the magazine or chamber easily and concentrate on getting your basics covered each time you pull the trigger.

    Timin' has a lot to do with the outcome of a rain dance.

    1


  • @rr2241tx said:

    Don't sweat the small stuff. Use a seating plug that doesn't mess up the bullet tip and seat your bullets just deep enough to feed from the magazine or chamber easily and concentrate on getting your basics covered each time you pull the trigger.

    Got a Forster Ultra Micro Seating die. Just did load development on a 6.5 CM. Just got a little bugged when the LOA was all over the place. Spoke to Berger tech support today and they said that their focus was consistent base to ogive, like you and others stated. Kinda surprised that inconsistent length in front of the ogive is not a big deal. Groups are good so Sunday I'll Chrono to get my fps for my ap.


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