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Why can't I get a consistant C.O.L.?

 
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  #15  
Old 03-19-2008, 12:27 AM
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Join Date: Sep 2006
Location: West coast/Washington
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Quote:
Originally Posted by goodgrouper View Post
I meant where did you run the concentricity dial on the loaded round? On the ogive, neck, or tip?
I can find factory ammo that is running .008" on the tip or ogive and it will go in the chamber fine.

I assume you are straightening the loaded round with a Bersin tool?

I still can't figure out why you have this bad of runout. If your chamber has bad alignent, your fired brass would show the bad concentricity. If your fired brass is good but your sized brass is bad, then the problem is in your dies. Something ain't right wherever it is and it isn't normal for a 30-06.
Goodgrouper,
I always check off the ojive.
One time when I was checking the "neck run out" on some of the casings that had 5-6 loads on them, I found a couple that were out .010 - .012. So I ran them thru the Redding die and they would only straighten up to .008, so I done two more passes on them and nothing changed.

So then I started checking the "body", this is where I discovered how much of a curve the whole case had. I don't remember what that measurement was now (several years back).

I have never heard of a Bersin Tool, but what I use is a 3/4" block of UHMW and with the appropriate holes drilled for the calibers I use, I just place the neck into the hole and with just a little "tweak", the bullet is brought back into alignment. I usually take them to .003 or less. It's quick and easy.

But anyway, I think you and I are thinking the same thing - chamber and barrel probably not in the best of alignment. Although, the rifle does shoot very well, all loads are down below 3/4" @ 100.

On last note; not all casing have this problem. Some brass is lots harder than others, so this problem is not on a consistent bases.

You said: I can find factory ammo that is running .008" on the tip or ogive and it will go in the chamber fine.
This is true, but, have you tired this when the bullet in the loaded round is only a few thousands from the riflings?
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Last edited by glassman; 03-19-2008 at 12:50 AM.
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  #16  
Old 03-19-2008, 05:51 PM
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Join Date: Sep 2004
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Quote:
Originally Posted by glassman View Post
Goodgrouper,
This is true, but, have you tired this when the bullet in the loaded round is only a few thousands from the riflings?

I can't remember if it was or not. It would all depend on the leade angle and where it started. I have dropped some of my 6ppc's on the concrete which have terribly thin necks and had them get bent out .005" and they still went in. They didn't shoot real great but they chambered. I jam those bullets into the riflings .005".

Here is a link to the Bersin in case you're interested:
catalog_49
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  #17  
Old 03-20-2008, 11:01 AM
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The link to the Bersin Tool is kinda messed up, can't read portions of it, it's got a lot "over lapped" writing.

But it looks like a fine tool for sure, but do I really need it?
Although I am a very accuracy mined type of guy, my shooting now days doesn't really require anymore "advance" tools.

But thanks for the link anyway.
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  #18  
Old 03-29-2008, 01:08 AM
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Unless I'm missing something this is a very easy question to answer...

Here's the long winded version:

Take a close look at the shape of the tips of the SKM's verses the V-max's. The V-max's should be/will be much more consistent. To put it into perspective, I just plucked a hair off of my beard and measured it in my caliper at 0.005", so a measured COL difference of +/- 0.005" is roughly +/- one facial hairs diameter difference. I'm surprised the difference that you are measuring is not more than the 0.005". I'm looking at some 190 gr SMK's right now and can see plenty of variance in the tips (what I am seeing is that some of the hollow points are somewhat flat across the tips and some are slightly angled). Now that I have beat that horse to death...

Bullet seaters in general, and the Redding Competition Seater specifically, do not push the bullet into the case from the point of the tip, but from somewhere further down on the bullet with a plunger. If necessary, you can take your die apart to see this.

Now, to your practice of seating long and then 'custom' seating every SMK bullet to the same C.O.L., here's my suggestion, Don't Do It! I'm surprised that no one else has chimed in and said this yet. Here is why:

1) The variances in the SMK tips (and thus the variances in C.O.L. based on these differences in the SMK tips), will make little difference on the overall accuracy of a bullet, especially when compared to the potential accuracy penalties that you will get from varying the distance that the bullet jumps before it contacts the lands. Since the seating plunger is contacting the front of the bullet somewhere close to the ogive (or at least in an area of the bullet that is far more consistent with the ogive than the tip of the bullet), you are likely changing the amount of 'jump' the bullet makes to the lands every time you adjust your micrometer die in an effort to 'even up' the C.O.L., as measured from base-to-tip with calipers.
2) It is possible that if your SMK's were already rather close to contacting the lands, that your seating die micrometer adjustments (done to make the base-to-tip measurements of the bullets equal) could be putting some bullets just into the lands, and some bullets just out of the lands, explaining why some rounds feel harder to chamber.
3) If the differences in C.O.L. continue to bother you, you can either measure your C.O.L. from the base of the case to the ogive of the bullet, using a bullet comparter such as the Stoney Point (now Hornady) tool, or you can trim the metplates of your SMK's, using a metplate trimmer.
4) I would recommend that once you get your seating depth where you want it, just ignore the measured C.O.L. (from base-to-tip) and enjoy shooting the SMK's. That is what I do.

Last edited by Rymart; 03-29-2008 at 01:16 AM.
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  #19  
Old 03-29-2008, 10:57 AM
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Join Date: Dec 2007
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Quote:
Originally Posted by Rymart View Post
Unless I'm missing something this is a very easy question to answer...

Here's the long winded version:

Take a close look at the shape of the tips of the SKM's verses the V-max's. The V-max's should be/will be much more consistent. To put it into perspective, I just plucked a hair off of my beard and measured it in my caliper at 0.005", so a measured COL difference of +/- 0.005" is roughly +/- one facial hairs diameter difference. I'm surprised the difference that you are measuring is not more than the 0.005". I'm looking at some 190 gr SMK's right now and can see plenty of variance in the tips (what I am seeing is that some of the hollow points are somewhat flat across the tips and some are slightly angled). Now that I have beat that horse to death...

Bullet seaters in general, and the Redding Competition Seater specifically, do not push the bullet into the case from the point of the tip, but from somewhere further down on the bullet with a plunger. If necessary, you can take your die apart to see this.

Now, to your practice of seating long and then 'custom' seating every SMK bullet to the same C.O.L., here's my suggestion, Don't Do It! I'm surprised that no one else has chimed in and said this yet. Here is why:

1) The variances in the SMK tips (and thus the variances in C.O.L. based on these differences in the SMK tips), will make little difference on the overall accuracy of a bullet, especially when compared to the potential accuracy penalties that you will get from varying the distance that the bullet jumps before it contacts the lands. Since the seating plunger is contacting the front of the bullet somewhere close to the ogive (or at least in an area of the bullet that is far more consistent with the ogive than the tip of the bullet), you are likely changing the amount of 'jump' the bullet makes to the lands every time you adjust your micrometer die in an effort to 'even up' the C.O.L., as measured from base-to-tip with calipers.
2) It is possible that if your SMK's were already rather close to contacting the lands, that your seating die micrometer adjustments (done to make the base-to-tip measurements of the bullets equal) could be putting some bullets just into the lands, and some bullets just out of the lands, explaining why some rounds feel harder to chamber.
3) If the differences in C.O.L. continue to bother you, you can either measure your C.O.L. from the base of the case to the ogive of the bullet, using a bullet comparter such as the Stoney Point (now Hornady) tool, or you can trim the metplates of your SMK's, using a metplate trimmer.
4) I would recommend that once you get your seating depth where you want it, just ignore the measured C.O.L. (from base-to-tip) and enjoy shooting the SMK's. That is what I do.
That's exactly what I have been doing lately,I bought a bullet caparator,settled in on a length to the ogive and set every bullet the same.I realised I was making a mistake by individually seating each one.Now i just set up the seater die and just seat them all wwithout worrying about the COL.
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