Coal

Discussion in 'Reloading' started by Fla shooter, Feb 18, 2012.

  1. Fla shooter

    Fla shooter Well-Known Member

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    Have ? Trying to measure lands !i made a chamber gauge driled n tapped 180 berger .put my bolt in took my cleanin rod with plastic insert screwed n put down the barrel then put clamp on rod took bolt out took the bullet n ran it n chamber till it stopped . Put rod down the barrel put clamp on rod came up with 3.508 ! This is a 7mm rm is this short for a 7mm coal
     
    Last edited: Feb 18, 2012
  2. joe0121

    joe0121 Well-Known Member

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    English?
     

  3. Mikecr

    Mikecr Well-Known Member

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    If your reading is right with that plastic insert, a 3.508" COAL would have a 180vld seated .525" into the neck(.305" of bullet bearing).
    Seems fine to me.
     
  4. Fla shooter

    Fla shooter Well-Known Member

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    Thanks im just starting to reload gotta lot to learn
     
  5. AZShooter

    AZShooter Well-Known Member

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    Sounds like alot of work to figure out where your bullet is located. So now you theoretically know where the bullet is located. Not sure what your information will do for you. IMO you don't actually need to know where it is located. Most repeating rifles won't allow you to engage the rifling and still fit the magazine box. I am not sure what you are tying to do.

    If you trying to prevent the bullet from touching the rifling then there is a fast and easy way to check. If a bullet is seated out so it will engage the rifling you can see the marks from the rifling easily if you first polish the bullet jacket with some steel wool. SO if you polish the bullet and don't see any marks after placing the dummy round in the chamber the bullet is not touching.

    If the bullet isn't touching the rifling which im my opinion is preferred for most hunting rifles AND it fits and feeds from magazine just work up your load.

    Sure there are advanced techniques for handloading in regards to bullet seating depth. Many of my hunting rifles shoot very well with a the bullet seated out as far as possible and still fit and feed from magazine and not touching the rifling.

    Final note the loading books usually mention cartridge overall length (OAL) as a reference. You can compare your length to the book if you are interested.
     
  6. Fla shooter

    Fla shooter Well-Known Member

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    My understanbing is you must know where lands are to reload . Ive shot HSM BERGERS IN IT AND ThEY DONT SHOOT WELL n from what I have read they will shoot better close or touching lands
     
  7. AZShooter

    AZShooter Well-Known Member

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    Possibly will shoot better IF you can engage the rifling. If you are trying to get a repeater to shoot you are limited by the magazine length. If you have to engage the rifling you can always single load.

    I have a 257 weatherby that shoots the 115 VLDs with a .100" jump. I have a friend that is very good at getting VLDs to shoot from hunting rifles. He experiments with some pretty large bullet jumps to get the individual rifle to shoot. No hard a fast rule in getting a VLD to shoot accurately. Read Berger's recommendations:

    "For years we have relayed that it is best to jam the VLD into the lands for best performance. This works for many rifles however there are many rifles that do not shoot the VLD well when the bullet is jammed. We have learned that the VLD can shoot best as much as .150 jump off the rifling. VLD bullets can be sensitive to seating depth and it has been found that these bullets shoot best in a COAL “sweet spot”. This sweet spot is a COAL range that is usually .030 to .040 wide.

    The quickest way to find this sweet spot is to load ammo at four different COAL. Start with a COAL that allows the bullet to touch the rifling. The next COAL needs to be .040 off the lands. The third COAL needs to be .080 off the lands. The last COAL needs to be .120 off the lands. One of these COAL will outperform the other three by a considerable margin. It has been reported that the VLD bullets don’t group as well at 100 yards but get better as the bullet “goes to sleep” at further ranges. We have learned that by doing the four COAL test you will find a COAL where the VLD bullets will group well at 100 yards. Once the COAL that shoots best is established you can tweak +/- .005 or .010 to increase precision or you can adjust powder charges and other load variables. Frankly, those who do the four COAL test usually are happy with the results they get from this test alone. "


    There is hope though...switch to a hybrid. You'll get a higher BC and a very friendly bullet regarding seating depth. I know, I have tried three and two HAD a large jump to rifling but shot bugholes. My 6mm-284 uses a .065" jump with 105 hybrids, 300 RUM over .100" with 168 hybrids.
     
  8. Mikecr

    Mikecr Well-Known Member

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    I think FLA shooter is doing just what he should be doing.
    He can make a dummy round with 3.508 COAL(using drilled/measure bullet), then measure his MaxOgvOAL with a comparator like Sinclair's 'nut' & log it.
    With this he has a reference point for his chamber with which to describe/log further seating adjustments.

    He can go coarse seating adjustments to get in the ballpark, then go to fine adjustments to really dial in best grouping(as Berger recommends).
    Optimum seating while not jammed can hold a wide window, or a very narrow window.
    I have a Cooper in 223 that shoots 52gr Jayners at 8thou off the lands. 5thou, or 15thou, and you wouldn't think it was the same gun shooting.
    I found this in 5thou adjustment steps(semi-coarse) as 10thou besting others. Then I dialed into 8thou and have been there for a long time, even with powder/primer changes.
    It's mother of mystery to me, and for understanding of it, I would give up all things shooting and walk away content.