Interesting results from my new Sinclair concentricity gauge...

Discussion in 'Reloading' started by engineer40, Jul 23, 2015.

  1. engineer40

    engineer40 Well-Known Member

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    I am new'er to rifle reloading. I've been at it a couple months now.

    I have this cheap 30-06 that shoots factory ammo below .75 inch consistently at 100 yards. Even the cheap Prvi stuff. My goal with reloading was to get it below .5 inch.

    I was getting frustrated with my reloading because I was averaging around 1.25 inch groups. I use good components; Lapua brass, Nosler Competition 168gr bullets and also Hornady Amax 178gr bullets, CCI primers, IMR4350 or IMR4064...

    I eventually talked myself into believing that my electronic digital scale must be junk so I purchased a standard RCBS balance beam style. It all checks out so that wasn't my problem.

    After some research I realize, Oh! It has to be my cheap Lee dies I'm using. I must have too much runout. My ammo is probably not concentric.

    Except it is... It's very concentric.

    I measured the mouths of full length resized never fired Lapua brass. The dial barely wiggles, not even a fraction of .001. All good with my full length resizing die.

    I measured the mouths of once fired brass that I collet neck sized. Again the dial barely wiggles. All good.

    I measured ammo with the bullets that I've seated with my Lee die. Once again, the dial barely wiggles. Probably 1/5th of .001.

    I wanted to make sure I was using the gauge correctly so I went and grabbed some old military surplus 7.62x54R and 303 British ammo that I have. I found out, yes, the gauge is definitely working.

    My results of my own reloaded ammo was just surprising to me. I was fully expecting to have quite a bit of runout for a couple reasons.
    1) I've been told you should barely feel the expander ball in your full length resizing die. And if you do feel it grab too hard you should sand it down a tiny bit. Well, mine actually does grab hard when I'm full length resizing. Especially with the thicker Lapua brass. My Lee dies must be machined good because my concentricity measurements are showing it's not distorting anything in the case mouths.
    2) I'm not using the Redding/Forster/Wilson high end reloading dies. ( I watched a video where a guy compared bullet seating runout using RCBS dies vs Redding bushing dies and the results were drastically different ).

    I'm curious if most of the reason I don't have concentricity problems is because I'm using the very stout Lee Classic Cast press. I would imagine there is no flex in this thing when I'm cam'ing up and down.

    Now I'm super anxious for my Hornady OAL gauge and comparators to come in the mail! I've tried different bullet seating depths but I think it's time I test using the method described in the Sticky.
     
  2. barefooter56

    barefooter56 Well-Known Member

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    engineer40,
    Sounds like you hit the lottery! In regards to the use of the SINCLAIR concentricity gauge. It is best used on FIRED cartridge cases. Keep in mind that the last "forming die" that a cartridge case goes through is your chamber . So a cartridge case that is suspect before firing MAY be well within specs.
    (.000-.005) indicated runout taken on a seated bullet with the probe of the indicator on the bullet as close to the bullet /casemouth junction as you can get it. Your checking of the cartridge case as you got it from the chamber and after it went though each die is also correct usage of this tool. Most concentricity issues are, especially with dies that have a locking screw that goes through the lock ring to contact the treads of the die. Are due to the die getting "cocked" in the die threads due to where the locking screw has contacted the threaded portion of the die body. A quick check is to back this screw out away from the threads of the die body so the die is now "floating " in the threads of the press. Run another checked fired case through the die in this condition and see if the runout improves to within the .000-.005 runout specs. Now to fix this issue you can get a prper diameter o-ring from the hardware store. Place it under the lock ring. Screw the die into your press until the o-ring is slightly compressed . Loosen the lock screw in the lock ring and re-adujust your die then re-tighten the lock screw in the lock ring. Or replace your lock rings with "cross-bolt style like Forster or Sinclair. Glen Ziedikers book HANDLOADING FOR COMPETITON has many hardware store fixes for concentricity problems. Making your dies so they can "float" in the press threads and self center on the round like your LEE dies seem to be doing due to the o-ring in the lock ring is a good thing. And remember "if it aint broke, dont fix it > LOL !!
     
  3. engineer40

    engineer40 Well-Known Member

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    Thanks for sharing all of that information barefooter56! I might need to acquire that book you suggested. I understood the majority of what you said but some of it might require pictures for me to grasp entirely as some of it is still new to me.

    When you say "o-ring", are you talking about a rubber o-ring to help "float" the die? I'm asking because I do use the Hornady die bushings to convienently switch my Lee dies in and out of the press. And I noticed those do have a rubber o-ring along the bottom. Now I'm curious if those bushings are doing for me the same "fix" that you suggested.
    ( http://www.amazon.com/Hornady-44099...sim_200_4?ie=UTF8&refRID=0Q5S0JEWE1E7B19FWFKH )
    ( Amazon.com : Hornady Lock N Load Die Bushing 10 Pack : Sports & Outdoors )
     
  4. barefooter56

    barefooter56 Well-Known Member

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    engineer40,
    Yes! Just a good old rubber o-ring under the lock ring. The o-ring on the Honady lock-n-load system does the same thing and it helps to keep the bushing from becoming unlocked from the locking grooves in the press. If you look at the description of a Forster loading press you will notice that the dies do not screw in. They float in the area that the lock ring goes into to hold the die in place. That is one of the reasons that press has such a good reputation for tuning our great ammunition. Glens book is a great resource for the loading bench.
     
  5. rcoody

    rcoody Well-Known Member

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    Sounds like you are headed down the right path.

    You assumed that your powder charges were inconsistent and ruled that out

    You assumed that the inexpensive lee dies were inducing too much runout and you eliminated that.

    now you are moving to seating depth. the OAL gage is a great tool. Knowing you chamber overall length is important. You probably already know this but each one of your bullets will have a different point where it contacts the lands. You will have a different measurement for each one.

    Now I am going to ask a silly question. How many different loads and what powder did you use in your original shooting for groups test. I recommend starting near the lowest recommended charge and with an '06 moving up in 0.5 grain increments until you get pressure signs or reach the max recommended load. When you did this did one powder charge stand out with the best group?
     
  6. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Barefooter,

    Why do you recomend checking runout as close to the case mouth as possible?
     
  7. engineer40

    engineer40 Well-Known Member

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    I did test different powder charges. The very first time I reloaded any rifle ammo, I did start at the lowest charge. They all went boom fine; which was my goal the first time.

    I then loaded some IMR4350 in .5 increments but I started just below mid charge weight, not at the very bottom. None of those loads were exceptional. Ranging 1.25 inches to probably 2.25 inches using 4 shot groups. But I was shooting in direct sunlight on a 90 degree day. I don't think my barrel ever had a chance to cool.

    I have 40 more rounds loaded right now to test at different powder weights using IMR4064 at .5 grain increments. I just paid for a membership at a local shooting range and I should have my range access information in the mail within a few days. This will help my testing because I'll be shooting from a shaded rest with a more solid bench.

    The biggest reason why I think it might be mainly a bullet seating depth issue right now is both of the factory ammo's that I've shot through the rifle used flat based bullets, which I've heard are less susceptible to seating depth throwing off accuracy than both of the higher BC, ogive, boat tail style bullets I've reloaded with. And so far, both cheap factory ammo's have shot more accurate than anything I've reloaded.

    I mean, I've "read and heard" so many things sometimes reloading seems like witchcraft. So my above assumptions may not be correct.
     
  8. engineer40

    engineer40 Well-Known Member

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    I was curious of the same thing?
     
  9. barefooter56

    barefooter56 Well-Known Member

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    Canadian Bushman,
    Because you are on the bearing surface of the bullet.
     
  10. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Isnt the goal of using the concentricity gauge is to measure the straightness of the bullet in relation to the case along its longitudial axis.

    If measuring further away from the place where the bullet and case meet, wouldnt this project the tolerance and give the reloader a greater resolution of the actual straighness of the cartridge?

    I.E. If you indicate the b.s. and move along the bullet headed toward the meplat, whats the odds your runout will increase?

    If you measure the tip of the bullet and move toward the neck, whats the chance the runout will increase?

    If you are truely only inducing concentricity errors then the number should be the same along the entire bullet. However if you have a straightness error will it not be more evident at the meplat?
     
  11. barefooter56

    barefooter56 Well-Known Member

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    The "nose" of the bullet is hanging out in space in the barrel. The bearing surface is what will contact the rifling. If the bearing surface is concentric (.000-.005 TIR). The bullet will hit the lands squarely. This will square up the nose section of the bullet also.
     
  12. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Can the nose of the bullet be pointing of axis, while showing concentric indication where the bullet is held by the case?

    Would this situation be just as detrimental to accuracy as a bullet that ran out on an axis parallel to that of the case?
     
  13. rcoody

    rcoody Well-Known Member

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    You can measure concentricity any where you want on a loaded round. The best place to measure in my opinion is at the ogive of the bullet. That is the first part of the bullet to meet the rifling.

    here is a little article about seating dies and runout. Most of the runout is caused by the sizing die. that is one of the reasons neck sizing is so popular.


    The Rifleman's Journal: Reloading: Seating Die Runout
     
  14. Barrelnut

    Barrelnut Well-Known Member

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    The indicator gauge is not as accurate close to the tip because it is measuring on a slanting surface and the gauge tip is not 90 degrees to the measuring surface.

    I just tested it. I had .001 runout on a 6.5 creedmoor with a 140 VLD. I tested at the bearing surface and got .001. I then tested closer to the bullet tip and got nothing...