Go Back   Alberta Outdoorsmen Forum > Main Category > Guns & Ammo Discussion

Reply
 
Thread Tools Display Modes
  #1  
Old 07-13-2019, 10:09 AM
chuck chuck is offline
Suspended User
 
Join Date: May 2007
Posts: 11,706
Default Concentricity observations.

I've been loading off and on for the 7MM Mashburn since 2012. Love the round, but not being a SAAMI cartridge it has its issues. Reamers are not standardized and the selection of dies is extremely limited. RCBS, for years, has been the only one offering them (they still are the only ones offering form dies), but my late friend Bob Farese sent cartridges to Redding in 2012 and they are now offering dies. Both options are extremely expensive.

I own a set of the RCBS dies, form 300 WW Win Mag brass and have always had concentricity issues. Most of which comes from the seating process. I generally notice concentricity issues with seating any cartridge which baffles me to some extent. There are likely several factors.

With FL sizing, I have completely removed the expander ball stem and run cases into the die. They go in concentric and come out the same way. I have long believed that a non-bushing FL setup with no expander will produce cases with almost zero run out. Bushing dies produce some. Argue that as you wish. But we have chambers that are perfectly concentric cut with reamers. Dies are cut the same way. Generally, they are concentric. Bushing dies offer infinite flexibility in neck tension and are much cheaper than a set of varying custom dies with custom necks to accommodate case hardening and brass variance.

Now to achieve proper neck tension I run the cases over a Sinclair expander mandrel. Run out starts to appear. Usually 1.5 to 2 thou. I attributed this to neck wall issues now being forced to the outside. This morning I decided to experiment with the expander ball. I put it into the die, let the expander ball float by not tightening the lock ring at the top of the die (I've done this lots) and when retracting the case stopped with the expander ball in the neck. Then I tightened the lock ring. In theory, it should now be relatively straight. I then ran cases already sized the previous way into the die and suprise suprise I knocked almost a thou of runout off the case consistently. Now we are at 0.001 of perceptible runout. And I have reduced three steps to one. Bonus.

But the seating is the problem. Consistently adding 5 to 6 thou more runout. I use a Forster Co-Ax press and with this setup, and with the long throat of this rifle my seating die is almost too short. I have to back the die body out for breathing space. So I backed the seating stem all the way up and bottomed it out (RCBS seating stems are removed through the bottom of the die) tightened the lock nut and set the seating depth with the die body lock ring using a dummy. I then seated bullets. Zero runout. Instead of going from 1 to 5 or 6 thou, these cases have gone from 1 to 0. I don't know why, but I don't care. :-)

All this is likely not repeatable with another cartridge and die set, but if you work at it for 7 or 8 years you can maybe come up with a solution. In spite of all this I still have a custom set of Whidden dies on order.
Reply With Quote
  #2  
Old 07-13-2019, 04:31 PM
qwert qwert is offline
 
Join Date: Jan 2012
Posts: 2,337
Default

Thank you for the uncharacteristically long and fully informative information.
I really appreciate the objective data and experience. I do have a couple of questions.

Quote:
Originally Posted by chuck View Post
snip
With FL sizing, I have completely removed the expander ball stem and run cases into the die. They go in concentric and come out the same way.
Please confirm
Typical (aka hunter class) RCBS solid FL die with typical RCBS expender button & deprime pin holder removed?

Quote:
Originally Posted by chuck View Post
snip
Now to achieve proper neck tension I run the cases over a Sinclair expander mandrel. Run out starts to appear. Usually 1.5 to 2 thou.
I attributed this to neck wall issues now being forced to the outside.
IMHO this is a good description of process.
https://www.whiddengunworks.com/stan...eloading-dies/

Please confirm, if annealing, neck turning or uniforming performed in post fire-forming case prep?

Quote:
Originally Posted by chuck View Post
snip
I then ran cases already sized the previous way into the die and suprise suprise I knocked almost a thou of runout off the case consistently. Now we are at 0.001 of perceptible runout.
Please confirm
1- sized in FL die with button expander removed
2- neck expanded with Sinclair mandrel
3- re-sized in FL die with button expander installed?

Quote:
Originally Posted by chuck View Post
snip
But the seating is the problem. Consistently adding 5 to 6 thou more runout. I use a Forster Co-Ax press and with this setup, and with the long throat of this rifle my seating die is almost too short. I have to back the die body out for breathing space. So I backed the seating stem all the way up and bottomed it out (RCBS seating stems are removed through the bottom of the die) tightened the lock nut and set the seating depth with the die body lock ring using a dummy. I then seated bullets. Zero runout. Instead of going from 1 to 5 or 6 thou, these cases have gone from 1 to 0. I don't know why, but I don't care. :-)
Please confirm
Typical (aka hunter class) RCBS combination seater & crimp die?
With the seater stem fully retracted, does the case mouth contact the crimp form in the die?

If your seater die is able to correct neck concentricity during seating, I suggest you take very good care of it.

Quote:
Originally Posted by chuck View Post
snip
All this is likely not repeatable with another cartridge and die set, but if you work at it for 7 or 8 years you can maybe come up with a solution. In spite of all this I still have a custom set of Whidden dies on order.
Did you order custom Whidden bushing or non bushing dies?
Is a carbide expander ball or cone available?

Please report results.

Good Luck, YMMV.

Last edited by qwert; 07-13-2019 at 04:39 PM.
Reply With Quote
  #3  
Old 07-13-2019, 08:33 PM
chuck chuck is offline
Suspended User
 
Join Date: May 2007
Posts: 11,706
Default

Quote:
Originally Posted by qwert View Post
Thank you for the uncharacteristically long and fully informative information.
I really appreciate the objective data and experience. I do have a couple of questions.



Please confirm
Typical (aka hunter class) RCBS solid FL die with typical RCBS expender button & deprime pin holder removed?



IMHO this is a good description of process.
https://www.whiddengunworks.com/stan...eloading-dies/

Please confirm, if annealing, neck turning or uniforming performed in post fire-forming case prep?



Please confirm
1- sized in FL die with button expander removed
2- neck expanded with Sinclair mandrel
3- re-sized in FL die with button expander installed?



Please confirm
Typical (aka hunter class) RCBS combination seater & crimp die?
With the seater stem fully retracted, does the case mouth contact the crimp form in the die?

If your seater die is able to correct neck concentricity during seating, I suggest you take very good care of it.



Did you order custom Whidden bushing or non bushing dies?
Is a carbide expander ball or cone available?

Please report results.

Good Luck, YMMV.
1. Yes

2. Annealed and that’s it

3.cases were sized with the expander ball removed and necks expanded using the mandrel previously. I then sized them with the expander ball in place which seemed to improve concentricity.

4.no crimping

I’ve ordered the Whidden fl bushing die.
Reply With Quote
  #4  
Old 07-13-2019, 10:37 PM
qwert qwert is offline
 
Join Date: Jan 2012
Posts: 2,337
Default

IMHO, If you can consistently achieve .001” concentricity, with std RCBS dies, you are doing very well, (or experiencing possible measurement error).
I suspect you will do better with the Whiddens.

I suspect we agree on the importance of concentricity to avoid bullet yaw entering the throat/leede area and any possibility of the bullet swaging itself so the point is off bore center, (and fly in a ‘barrel roll’?, or at least in an unbalanced state?).

IMHE, case neck wall thickness variability can cause concentricity problems with most types of sizers. I suspect any die using an internal expander will cause any “neck wall issues now being forced to the outside”. Your concentricity gauge (IIRC a Sinclair with 4 balls and a vertical dial indicator?) may show this by indicating off the neck and then the side of the bullet adjacent to the neck.

IMHO, any neck wall thickness or hardness variability may cause the thin section of wall to yield sooner than thicker and stronger sections, which may cause the bullet base to yaw as it is released and starts into the throat.
Similarly, when being resized and expanded, the thin section will be worked more than the thicker sections, work harden at a different rate, and explain location of longitudinal neck fatigue cracks.

Many suggest that the combination of inconsistent wall thickness and expander friction may also tend to pull the neck out of concentricity. Some suggest carbide expanders might reduce this.

Some suggest that outside neck turning to uniform the wall is beneficial, and that turning an entire batch of brass to a consistent wall will result in greater average concentricity for the whole batch, and allow resizing with bushing only and no expander.
Others submit this can lead to formation of ‘donuts’ inside the neck / shoulder junction, and suggest that using a bushing that results in just a small amount of work to be completed by the expander ball.

I have 5 bushings for each bore caliber I load, (some think this is excessive, I like good tooling).

I suspect (hope?) that Collet Neck dies may slowly move brass from thick to thin areas of the neck wall, and are more tolerant of varying wall thickness, (YMMV).

You are experienced and knowledgeable enough to recognize you are at a high point of the bell curve, where small improvements become harder to achieve.
You also know that consistency is the proven route to precision.
I am confident you will achieve both.

Good Luck, YMMV.
Reply With Quote
  #5  
Old 07-14-2019, 06:06 AM
Don_Parsons Don_Parsons is offline
 
Join Date: Jul 2016
Posts: 1,819
Default

I took a reloader course this spring,,, I can't share on how it's done due to the copy right thing,,, and those who choose to learn this stuff are more than welcome to PM me for details on who offers this training...

I agree that our measuring tools go through a test to make sure there up to task,,, and the little tricks of the trade to confirm this...

Those of us that attend course 2 of the 4 offered this year learned a neat trick to get the most out of the concentric dial gauge that most folks over look...

The trick is to get less then 0.001 run-out,,, 0.0075 is good,,, 0.0050 is way awesomeness... Ha... Staying just below the 1 is tricky with the frugal gauging tools I have...

I agree,,, if I get 1 thou run-out or a fraction below the 1,,, I'm good to go...

Using the ideas we learned at the Reloader course II was well worth the funds as it dosen't cost alot of money so long as the gauging tools are calibrated for the job...

There are lots of other factors that play a more important role in """my""" hunting, shooting, and ammo loading category then over thinking just 1 factor then the others...

Today is the simple old school ladder test to get my new pipe to luanch booltiz into a tight water-line,,, best so far with the now broke in barrel is a 2 1/2" spread from 14 shots at 400 yards,,, Ha... Of course I had to miss count my shots to remind me that CDO is part of my game plan...

Cheers from the Eastern Slopes of Alberta

👍
Reply With Quote
  #6  
Old 07-14-2019, 07:51 AM
Bushrat's Avatar
Bushrat Bushrat is offline
 
Join Date: May 2007
Posts: 5,703
Default

Quote:
Originally Posted by qwert View Post
IMHO, If you can consistently achieve .001” concentricity, with std RCBS dies, you are doing very well, (or experiencing possible measurement error).
I suspect you will do better with the Whiddens.

I suspect we agree on the importance of concentricity to avoid bullet yaw entering the throat/leede area and any possibility of the bullet swaging itself so the point is off bore center, (and fly in a ‘barrel roll’?, or at least in an unbalanced state?).

IMHE, case neck wall thickness variability can cause concentricity problems with most types of sizers. I suspect any die using an internal expander will cause any “neck wall issues now being forced to the outside”. Your concentricity gauge (IIRC a Sinclair with 4 balls and a vertical dial indicator?) may show this by indicating off the neck and then the side of the bullet adjacent to the neck.

IMHO, any neck wall thickness or hardness variability may cause the thin section of wall to yield sooner than thicker and stronger sections, which may cause the bullet base to yaw as it is released and starts into the throat.
Similarly, when being resized and expanded, the thin section will be worked more than the thicker sections, work harden at a different rate, and explain location of longitudinal neck fatigue cracks.

Many suggest that the combination of inconsistent wall thickness and expander friction may also tend to pull the neck out of concentricity. Some suggest carbide expanders might reduce this.

Some suggest that outside neck turning to uniform the wall is beneficial, and that turning an entire batch of brass to a consistent wall will result in greater average concentricity for the whole batch, and allow resizing with bushing only and no expander.
Others submit this can lead to formation of ‘donuts’ inside the neck / shoulder junction, and suggest that using a bushing that results in just a small amount of work to be completed by the expander ball.

I have 5 bushings for each bore caliber I load, (some think this is excessive, I like good tooling).

I suspect (hope?) that Collet Neck dies may slowly move brass from thick to thin areas of the neck wall, and are more tolerant of varying wall thickness, (YMMV).

You are experienced and knowledgeable enough to recognize you are at a high point of the bell curve, where small improvements become harder to achieve.
You also know that consistency is the proven route to precision.
I am confident you will achieve both.

Good Luck, YMMV.
Well said. Years ago I went to turning necks, have never looked back. Seating concentricity issues disappeared even with ordinary off the shelf standard dies. If one side of the neck is thicker than the other you will always be fighting it. Also if the case mouth is not perfectly square the bullet will contact the high side of the neck first when beginning to seat and tip the bullet out of alignment as it is seated. The neck even if perfectly straight and aligned will not straighten a tipped bullet or a bullet that is not aligned to go into the neck perfectly straight. If it enters the neck upon seating tipped or off center it will be crooked when fully seated. The brass neck is the weakest link and will deform to accommodate this misalignment, it doesn't have the strength to 'straighten' an already misaligned bullet as it is being seated.

Square case mouth with a proper concentric chamfer + equal neck thickness around its circumference + straight, centered and aligned bullet as it enters the case mouth = straight ammo.
Reply With Quote
  #7  
Old 07-14-2019, 09:06 AM
Davey Boy's Avatar
Davey Boy Davey Boy is offline
 
Join Date: Nov 2013
Location: SW Calgary
Posts: 1,038
Default

Curious if anyone has used the Hornady Concentricity Guage to improve their concentricity. Comments are welcome.

https://www.bing.com/videos/search?q...0469&FORM=VIRE
Reply With Quote
  #8  
Old 07-14-2019, 10:45 AM
chuck chuck is offline
Suspended User
 
Join Date: May 2007
Posts: 11,706
Default

I have tools that are designed to correct runout. However, I think they alter neck tension which I don’t think is particularly helpful to accuracy.
Reply With Quote
  #9  
Old 07-14-2019, 01:05 PM
Davey Boy's Avatar
Davey Boy Davey Boy is offline
 
Join Date: Nov 2013
Location: SW Calgary
Posts: 1,038
Default

Quote:
Originally Posted by chuck View Post
I have tools that are designed to correct runout. However, I think they alter neck tension which I don’t think is particularly helpful to accuracy.
Yes I have heard that as well. Guess best is to have good reloading skills and good brass and bullets to start with.
Reply With Quote
  #10  
Old 07-14-2019, 01:18 PM
Salavee Salavee is online now
 
Join Date: Sep 2008
Location: Parkland County, AB
Posts: 3,408
Default

Richard Lee may have an anwser for the concentricity issue without spending a SL of money.
__________________
When applied by competent people with the right intent, common sense goes a long way.
Reply With Quote
  #11  
Old 07-14-2019, 01:21 PM
Bushrat's Avatar
Bushrat Bushrat is offline
 
Join Date: May 2007
Posts: 5,703
Default

Quote:
Originally Posted by Davey Boy View Post
Curious if anyone has used the Hornady Concentricity Guage to improve their concentricity. Comments are welcome.

https://www.bing.com/videos/search?q...0469&FORM=VIRE
Had one when they first came out for a while but it had problems, the chucks that hold the tip of the bullet were undersized for the machined hole in the stand/cradle they fit in. They wobbled around loosely with a lot of play making it hard to measure run out let alone correct it. I assume the newer units are manufactured to better specs. I agree with Chuck that correcting run out with these type of tools has an effect on neck tension especially with short bullets that are not seated very deep into the neck.
Reply With Quote
  #12  
Old 07-14-2019, 03:09 PM
duceman duceman is offline
 
Join Date: Aug 2008
Location: south of calgary
Posts: 1,649
Default

Quote:
Originally Posted by Salavee View Post
Richard Lee may have an anwser for the concentricity issue without spending a SL of money.
yup.
__________________
220swifty

1. People who list their arguments in bullets points or numerical order generally come off as condescending pecker heads.

2. #1 is true.
Reply With Quote
  #13  
Old 07-15-2019, 05:06 PM
Davey Boy's Avatar
Davey Boy Davey Boy is offline
 
Join Date: Nov 2013
Location: SW Calgary
Posts: 1,038
Default Here is an interesting method

This fella has an interesting method of straightening runout.
He taps it instead of pushing the neck like the Hornady does.

And according to this guy, who is a top shooter in the US it works, but his invention is like 390 USD. But the fella using the tire guage is using the same principal.

Have a look and the video of the top shooter's invention is about halfway down.

http://forum.accurateshooter.com/thr...-tool.3927609/

Expensive way. http://premieraccuracy.com/index.html
Reply With Quote
  #14  
Old 07-16-2019, 02:46 AM
SuperCub's Avatar
SuperCub SuperCub is offline
 
Join Date: May 2014
Location: SJ, NB
Posts: 176
Default

I use Lee Collet Dies and Forster Benchrest Seating Dies for all but one of the rifles I own.
__________________
Hark, a Fudd draweth nigh.
Reply With Quote
  #15  
Old 07-16-2019, 06:53 AM
chuck chuck is offline
Suspended User
 
Join Date: May 2007
Posts: 11,706
Default

They are both fresh out of 7MM Mashburn dies.
Reply With Quote
  #16  
Old 07-16-2019, 07:30 AM
chuck chuck is offline
Suspended User
 
Join Date: May 2007
Posts: 11,706
Default

BUT, I just spoke with them and they will make custom dies!
Reply With Quote
  #17  
Old 07-16-2019, 01:39 PM
Don_Parsons Don_Parsons is offline
 
Join Date: Jul 2016
Posts: 1,819
Default

Crazy to think that factory ammunition some times has 0.005 thou run-out,,, yet it shoots ok for what it is,,, most likely close range stuff... Ha

https://www.outdoorlife.com/how-to-h...city-accuracy/

It's no wonder that I started reloading back in the 80's...

👍
Reply With Quote
  #18  
Old 07-16-2019, 02:01 PM
qwert qwert is offline
 
Join Date: Jan 2012
Posts: 2,337
Default

Quote:
Originally Posted by Bushrat View Post
Well said. Years ago I went to turning necks, have never looked back. Seating concentricity issues disappeared even with ordinary off the shelf standard dies. If one side of the neck is thicker than the other you will always be fighting it. Also if the case mouth is not perfectly square the bullet will contact the high side of the neck first when beginning to seat and tip the bullet out of alignment as it is seated. The neck even if perfectly straight and aligned will not straighten a tipped bullet or a bullet that is not aligned to go into the neck perfectly straight. If it enters the neck upon seating tipped or off center it will be crooked when fully seated. The brass neck is the weakest link and will deform to accommodate this misalignment, it doesn't have the strength to 'straighten' an already misaligned bullet as it is being seated.

Square case mouth with a proper concentric chamfer + equal neck thickness around its circumference + straight, centered and aligned bullet as it enters the case mouth = straight ammo.
IMHO, 'proper' includes smooth, and free of burrs or sharp edges that can resist insertion or scratch the finely polished jacket.

Fortunately, this does not require any specialized $$$ tooling.
I just use fine steel wool in any socket or 'nut-driver' that is comfortable in my hand. (Some might prefer to secure the wool holder to the bench.)

A simple twist or two & done. Your finger tip (and the bullet jacket) will easily feel the improvement.

Good Luck, YMMV.
Reply With Quote
  #19  
Old 07-17-2019, 09:32 AM
leeelmer leeelmer is offline
 
Join Date: Jul 2010
Location: Rocky Mnt House
Posts: 643
Default

Quote:
Originally Posted by chuck View Post
BUT, I just spoke with them and they will make custom dies!
I have had Lee make me a ton of custom dies, very good turn around time and cheep.
Had them do a factory crimp die for my 270Bee and one for my 358 Norma Mag.
Also had them do a few dead length seating dies and collet dies as well.
My 358 norma always had issues with the recoil moving the bullet along in the mag well after recoil, Now this problem is fixed with the factory crimp die.
I have switched to almost all Lee dies now, still have a few redding and a couple custom dies from shops in the states for my Nitro rifles, but Lee has consistently made dies that have less run out, and fixed issues for me that other dies have had.
Reply With Quote
  #20  
Old 07-18-2019, 08:02 AM
Deer Hunter's Avatar
Deer Hunter Deer Hunter is online now
 
Join Date: Jun 2007
Posts: 3,733
Default

I have seen less bullet run out if you seat the bullet in several strokes, turning the cartridge 90-180 degrees each time before it has been fully seated to the oal.
__________________

Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 09:01 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.