meplate uniforming

Discussion in 'Reloading' started by Andy D, Jun 13, 2006.

  1. Andy D

    Andy D Member

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    Thought I'd see if anyone might be able to explain the right way to uniform a bullet's meplate. Fom what I've read you remove around .005 to .007 of material. I need to know when I sort the bullets prior to trimming by measuring the base to ogive, do I adjust the amount of material I remove based on various "base to ogive lengths" or do I trim them all the same and only measure with a comparator to create consistency for shooting groups? Also what increments in base to ogive length should the 300gr SMK be reasonably sorted in?

    Thanks for any help
    Andy D
     
  2. EddieHarren

    EddieHarren Well-Known Member

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    Trimming the meplate should not alter the base to ogive length in any manner.
     

  3. Andy D

    Andy D Member

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    I realize that trimming the meplate does not alter the base to ogive length I was wondering if you need to trim varying amounts from the meplate depending upon different lots of bullets separated by varying "base to ogive lengths."
     
  4. Dan Carey

    Dan Carey Well-Known Member

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    The accepted theory is to only cut what's needed off the nose of the bullet. All bullets should be cut the same amount.

    It is yet to be proven there is any advantage when the bullets are shot at ranges shorter than 500 yards.
     
  5. Guest

    Guest Guest

    [ QUOTE ]
    The accepted theory is to only cut what's needed off the nose of the bullet. All bullets should be cut the same amount.

    It is yet to be proven there is any advantage when the bullets are shot at ranges shorter than 500 yards.


    [/ QUOTE ]
    Amen to both statements.
    I wouldn't bother shooting less than 500 yards.
    But for Long Range Hunting ( 1K+ ), it can have a significant advantage.
     
  6. Andy D

    Andy D Member

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    Thanks for all the input. It's much appreciated.
     
  7. goodgrouper

    goodgrouper Well-Known Member

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    I would even go so far as to say that it doesn't make much difference even at 1k. I have only really seen bad meplats make a difference on certain bullets past 1500 yards. A much more important and detrimental aspect to accuracy at these ranges is the bearing surface length and the length from ogive to base of bullet.

    Every bullet I load that will be shot at ranges of 800 yards or further will be measured for bearing surface length and loaded into my ammo box in rows with same lengths. If there are quite a few different lengths in my ammo box, I will make marks on the tip of the bullet with a sharpie to distinguish which is which.

    I personally have tested several VLD style bullets at 1500 yards out to a tad over 2000 yards and have seen .002" difference in bearing surface make as much as two feet of vertical impact!

    It is a drowsy job measuring bearing surfaces on every bullet you want to shoot but if you want to be deadly at longer ranges, it is a must! If we could just get bullets for our game that were as uniform as bullets for the 100 yard BR crowd, we would have records being broke on a weekly basis. They have come a long way from first introduction, but there is still room for improvement.

    I just got through measuring a new batch of Berger 140 grain VLD's for my 6.5-.284 and it was one of the worst lots I have ever seen come from Berger. They must have had their presses all screwed up the day they made this lot because there was .010" variation in length! Terrible. I will most likely just use this lot for varmints and forget trying to shoot groups with them even after sorting them out.

    Anyhow, hope this helps.
     
  8. Andy D

    Andy D Member

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    How do you properly measue bearing surface area? Is it the same as base to ogive length using a comparator and a set of calipers? I'm trying to improve my consistency with the 300gr SMK @ 800-1200 yards I seem to have sporatic high "flyers" as much as a foot at around 1000 yrds. Also, goodgrouper, I thought I might ask you, I'm having trouble with run-out on my loaded 338 rum rounds. I've tried
    squaring the die, the expander ball(I have not bought a set of bushing dies yet as I may get a different 338). I've tried different shell holders(loose and snug), sharp angle- chamfering, 2 sets of dies (hornady and RCBS) and case neck turning. I know that the Rem. brass I'm using is bad but i've neving had this much trouble getting straight ammo. Out of 50 rounds I'll get 15 rounds @ +/- .001, 15 round @ +/- .003 and the rest vary up to .008! Is this normal with Rem brass, or is the long 300 SMK a tough bullet to seat straight. I realize that my dies put me at a disadvantage but I've used non-redding standard dies before that are set up properly and gave got reasonable results. Does a guy have to buy 300 rounds of REM. brass to get 100 good ones? Any advice or ideas would be very valued as I'm ready to toss my dies and brass in the garbage.

    andy
     
  9. Guest

    Guest Guest

    Might want to give the Lee Collet Neck Die a try. Much less than a bushing die and works as good or better than a bushing die. And you don't have to turn necks or use lube.
     
  10. goodgrouper

    goodgrouper Well-Known Member

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    Andy,

    Got to run off to work now but I'll post back tonight on your questions.
     
  11. goodgrouper

    goodgrouper Well-Known Member

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    Andy,

    Unfortunately, you are trying to shoot one of the most inconsistent bullets for bearing surface on the market. Taking a Stoney Point bullet comparator and measuring from the ogive to the base won't cut it.

    There are several ways to measure the bearing surface or as close to the bearing surface as we can actually measure. None actually measure just the shank of the bullet. They also get a little of the boat tail in there too. The cheapest and still my favorite is to use two SP comparators (one on each blade of the caliper) and it works great. I marked one of my comparator bodies as "top" and then also marked my second set of inserts as "top". This way I can always be consistent on my measuring.
    The second method is the Tubb tool which I believe to be way overpriced and I know to be no better than the SP way.

    Using the SP method, I can say that on my last batch of 300 grain MK's, I had .013" variation in measurement. Most of that came from the front half of the shank to the ogive but there were a fair amount that had error in the last half of the shank to the boat tail. Interestingly enough, a few of these latter bullets showed no variation from base to ogive measure! This tells you that there IS inconsistencies in the boat tails of bullets. So it helps to measure from base to ogive but you might miss a few pills that will certainly give you fliers at long range.


    As for your concentricity issues, it sounds like you have a real head scratcher.

    Ok, I assume you are running the dial on both the fired, unloaded case (and finding straight cases) and the loaded ammo and the problem is truly coming from the loading process. I also assume that you are running a dial indicator on the loaded bullet from the tip to the case mouth, and on the neck of a turned case.

    If this is so, then it could be a few things.

    The first thing I would try is a bushing die with the correct bushing. The 300 grain MK bullet has a long bearing surface and usually measures .3385 diameter. Neither of these things help when trying to stuff it down a piece of brass that has been squeezed way down by a standard die that gives the brass very much bullet grip. Your expander ball should bring it back to the proper diameter but the brass may have tons of spring back and the die could be taking it down to .243 diameter for all we know.

    75% of the time, concentricity issues come about from the dies than any other thing. Brass usually makes up the last 25%. But brass is an easy thing to trouble shoot. Select a piece of brass that runs good concentricity one time and then check it again after firing and reloading it. If it is still good then take a bad one and run the same test. If the good stays good and the bad stays bad, then you have brass issues that your dies probably won't solve.

    If you determine it is the dies that are causing it, you will need to determine if it is the sizing die or the seating die. This is easy. Just run the dial over the sized case before seating the bullet. This will tell you what to do next-get a new sizer or a new seater. If it is the seater that is causing it, before you replace it, load a different bullet (preferably a shorter one) and see if the runout is still there. If it is, pitch that die!

    If it is the sizer causing it, try a bushing die or a different FL sizer.


    I had custom dies made for my 338 thunder (which is on the ultra mag case) and they run less than .001" runout even on my culls. My culls are straight but they were off in weight tolerances.

    And yes, it is a good rule of thumb to buy at least one more bag of Remmy brass from the same lot than what you think you need just to have some extra in case you have to cull out a few. /ubbthreads/images/graemlins/wink.gif

    Hope this helps.
     
  12. Andy D

    Andy D Member

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    Thanks for everyone's input. Thanks goodgrouper for taking the time to lay-out a good troubleshooting plan and lending your experience. It is very hlepful to have good advice when involved with such a potentially frustrating hobby.

    andy