Best method for increasing concentricity with loaded ammo

G

gene so

New member
Hello,

I competed long ago in LRBR with a 6.5 x 284 and now am getting ready to compete in F class open. I noted loaded ammo is "out" beyond .04. I also see I had a few resizing dies, almost certainly to fix this problem and I know I never did. I have a concentricity gauge with a 1/10,000's dial so it really "moves" when I rotate my ammo.

I have built a walnut block jig with four different bullets size holes reamed into it. These holes will allow me to place the bullet from loaded ammo tightly into these holes, and work the case so that the loaded round is as concentric as possible. I have tried this with some .244 ammo and was able to get them all concentric. 1. I am amazed that with a Wilson straight line seater, this ammo would be that far off in the first place. 2. Although I managed to make the loaded cases more concentric there seemed to be no rhyme or reason as to how I went about it, to this point. It mostly was blind luck.
I would like to make this process as efficient as possible. If you have a succesful process I would really like to read about it. I know it would take time and a "feel" to develop a consistent method. Thanks
 
gene so said:
Hello,

I competed long ago in LRBR with a 6.5 x 284 and now am getting ready to compete in F class open. I noted loaded ammo is "out" beyond .04. I also see I had a few resizing dies, almost certainly to fix this problem and I know I never did. I have a concentricity gauge with a 1/10,000's dial so it really "moves" when I rotate my ammo.

I have built a walnut block jig with four different bullets size holes reamed into it. These holes will allow me to place the bullet from loaded ammo tightly into these holes, and work the case so that the loaded round is as concentric as possible. I have tried this with some .244 ammo and was able to get them all concentric. 1. I am amazed that with a Wilson straight line seater, this ammo would be that far off in the first place. 2. Although I managed to make the loaded cases more concentric there seemed to be no rhyme or reason as to how I went about it, to this point. It mostly was blind luck.
I would like to make this process as efficient as possible. If you have a succesful process I would really like to read about it. I know it would take time and a "feel" to develop a consistent method. Thanks
Click to expand...

I'm assuming you m ant .004 inch, not .04.

In my experience, much of loaded round runnout can be traced back to the sizing operation, not the seating. A crooked case out of the sizer will not straighten up in a seater. Check your sizer for any slack or off enter in the sized portion of the neck.

Of course, you can straighten loaded cases, just be careful that you don't compromise the neck tension as the bullet is shifted in neck.

Also, I see shooters with various ammo straighteners whacking away as the bullet is supported on the tip. How do they know that they aren't bending the bullet, especially if using considerable neck tension.

I have one of the Bruno loaded round checkers. My loaded 6PPC and 30BR ammo consistently runs .001 or less.

I'm not sure how much is too much runnout. I have delibertly shot rounds that exhibited very little runnout with those that showed as much as .002, and could not tell the difference.

By the way, those that think the chamber will straighten a crooked round are wrong. It just doesn't work that way.
 
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The only practical use for a concentricity gauge is to diagnose die problems. I have never been able to get the final indicator (the target) to show that straightening loaded ammo works. Yes, I have a concentricity gauge that is well suited to the task of straightening. IMO you need to work on the source of the problem by switching to a better FL die. I should add that a bad seater can make runout worse than the same brass would give you with the best seater, but the best seater cannot fix the result of a bad FL die.
 
May I ask a related question

In the case where the freebore diameter is dang near the bullet diameter like in the case of the 223 Wylde where the freebore is 0.2240 (+/- whatever tolerance), assuming the chamber is cut straight, is runout still that critical since the bullet is almost encapsulated in its own diameter? Will the bullet start straight regardless where the case is pointing?
 
Just go shoot.
Your gun handling and wind will be a lot more important than how straight your round is. Practice is more important. I test a lot and never check how straight the round is.
 
Thanks for the input

Hello,

Thanks to your replies, I am gaining a true insight into the problem. I know from previous attempts to deal with the problem I ended up with two sizing dies and I will now use them side by side to see which one works best by using the concentricity gauge to show me which one resizes more true to concentricity.

Along this line, I plan on shooting Lapua brass in a new chamber on my 30" barrel. For the first time in over two decades I plan to use the factory brass without outside neck turning for a "no turn" neck.. So, what should the reamer specs be for proper clearance for the 6.5 x 284 Norma cases? Seems to me years ago that .003 was recommended for this cartridge.

Thanks again, your insight can save me a lot of frustrations.
 
Fix

1- when locking any die, do it with the die under pressure from the ram with a case in it.
2- have all contact surfaces of the dies and shell holders trued by a competent machinist.
3- annealing and neckturning play a role.
4- using a 22 degree vld chamfer tool helps.
5- lee collet die, wilson seating dies and xxi century bullet hydro seater
5- hygiene on the bench. black sticky grit from primer and powder burn accumulate in every friction surface. Cleaning case heads, base of dies and shellholders with methilated spirits (alcohol) will help keep all surfaces square.
After this you should have no runout (my dial gauge needle doesn't even twitch mostly after step 2- you'd be surprised at how un square dies are- even wilson).
 
Lou Murdica said:
Just go shoot.
Your gun handling and wind will be a lot more important than how straight your round is. Practice is more important. I test a lot and never check how straight the round is.
Click to expand...

I don't know whether straight rounds will shoot better but I like Lou's post. I used the same loading deal for a long time (years) and my success was related purely to the barrel and my ability to read conditions....mostly the barrel. Don't know if my loads were straight or not. In short...I don't think "straight" is better but rather another thing to worry about if you choose to worry.
 
Press ad dies?

You did not list your press or dies.

I was having a run out problem using a RCBS RockChucker press and RCBS dies and found that a Forster press and Redding dies and pretty much cured the problem. I also have a Harrell's press that I use for PPC and 30BR with Whidden dies made for my chambers and love the set up. I seat bullet for both using a Wilson die and arbor press.
 
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