Best concentricity gauge

[Vern Kowalski]

I'm not sure if I've posted this in the right place. I'm trying to get into long range hunting, and I'm looking for input from fellow nutters, particularly the precision handloaders as to what the best concentricity gauges are for checking runout. Which ones work well and which ones are junk. Please share your experiences. Thanks in advance.

Vern.

 

[IvoB]

would like to know as well

 

[bigedp51]

My 2 cents

If you full length resize, the case body has clearance in the chamber, meaning it doesn't touch the chamber walls.

The majority of concentricity gauges let the case rotate on the case body and the case body has no guiding effect in the chamber.

A neck sized case will have the case body touch the chamber walls and the body of the case can effect bullet alignment with the bore.

I have both gauges below and the RCBS gauge rotates on the case body and the Hornady gauge rotates the case on its base and bullet tip.

If you full length resize your cases the case is supported in the rear by the bolt face and by the bullet in the throat. Meaning the only part of the case touching the chamber is the case shoulder pushed forward by the ejector. (as long as the case isn't warped and banana shaped)

The U.S. Military considers match grade ammunition to be a cartridge with .003 or less bullet runout.

Bottom line if you full length resize with a Forster benchrest resizing die you will have less than .003 bullet runout.

NOTE, at the Whidden custom die website they tell you that a non-bushing full length resizing die produces the most concentric ammunition.

It is the cases with uneven case wall thickness that warp and become banana shaped that cause the majority of problems.

And the biggest cause of neck runout happens when the expander is locked down off center from the neck of the die.

On a bushing die if the case neck is reduced .004 or more it will induce neck runout. And why it is recommended to reduce the diameter in two steps if if reducing over .004.

Bottom line the average reloader with a off the shelf factory rifle will be well served with a $100.00 Sinclair concentricity gauge.

And a simple neck thickness gauge like below will tell you very quickly how uniform your case necks are. And a good gauge to have with a runout gauge to find problem cases.

 

[Vern Kowalski]

My 2 cents

If you full length resize, the case body has clearance in the chamber, meaning it doesn't touch the chamber walls.

The majority of concentricity gauges let the case rotate on the case body and the case body has no guiding effect in the chamber.

A neck sized case will have the case body touch the chamber walls and the body of the case can effect bullet alignment with the bore.

I have both gauges below and the RCBS gauge rotates on the case body and the Hornady gauge rotates the case on its base and bullet tip.

If you full length resize your cases the case is supported in the rear by the bolt face and by the bullet in the throat. Meaning the only part of the case touching the chamber is the case shoulder pushed forward by the ejector. (as long as the case isn't warped and banana shaped)

The U.S. Military considers match grade ammunition to be a cartridge with .003 or less bullet runout.

Bottom line if you full length resize with a Forster benchrest resizing die you will have less than .003 bullet runout.

NOTE, at the Whidden custom die website they tell you that a non-bushing full length resizing die produces the most concentric ammunition.

It is the cases with uneven case wall thickness that warp and become banana shaped that cause the majority of problems.

And the biggest cause of neck runout happens when the expander is locked down off center from the neck of the die.

On a bushing die if the case neck is reduced .004 or more it will induce neck runout. And why it is recommended to reduce the diameter in two steps if if reducing over .004.

Bottom line the average reloader with a off the shelf factory rifle will be well served with a $100.00 Sinclair concentricity gauge.

And a simple neck thickness gauge like below will tell you very quickly how uniform your case necks are. And a good gauge to have with a runout gauge to find problem cases.

Thanks for that. My hopes are to only neck size to not overwork the brass, then when the cartridge becomes tight to chamber, bump the shoulder back with a Redding body die.

 

[bigedp51]

Thanks for that. My hopes are to only neck size to not overwork the brass, then when the cartridge becomes tight to chamber, bump the shoulder back with a Redding body die.

Below Kevin Thomas who worked in the Sierra ballistic test lab and now shoots for Team Lapua USA.

Just remember that factory SAAMI chambers are on the generous side and many things that competitive shooters do with their custom chambered rifles is over kill for the average shooter.

The biggest improvement I made in reducing neck runout was by using Forster full length benchret dies with their high mounted floating expanders.

With the Forster dies the expander enters the case neck while the neck is held and centered in the die. And this prevents the expander from pulling the neck off center.

Below I added the Forster expander assemblies to my RCBS and Redding dies that greatly reduced neck runout.

 

[bigedp51]

Below is the difference in the type concentricity gauges, the top would be the Hornady type gauge and the bottom are the types that rotate on the case body.

 

[ffgats]

bigedp51
I find your post very informative and interesting. I have a Forester FL Sizing Die and Dillon SB FL SD, most of the time I use the Dillon since all the brass that are process fits into my JP gauge which is intended for my AR.
Any opinoins on the Dillon Die, they look very similar with Forester. Thanks

 

[bigedp51]

bigedp51
I find your post very informative and interesting. I have a Forester FL Sizing Die and Dillon SB FL SD, most of the time I use the Dillon since all the brass that are process fits into my JP gauge which is intended for my AR.
Any opinoins on the Dillon Die, they look very similar with Forester. Thanks

The biggest difference is the Dillon dies are small base dies and do not have the same type floating high mounted expander. Meaning the Dillon expander is higher than normal "BUT" the case neck is not held and centered in the die like the Forster.

 

[ffgats]

The biggest difference is the Dillon dies are small base dies and do not have the same type floating high mounted expander. Meaning the Dillon expander is higher than normal "BUT" the case neck is not held and centered in the die like the Forster.

Just got my Forester a few months ago, will make a comparison with my load with only the Sizing Die as the variable.

 

[308BAR]

I vote for the 21st Century Wheel Concentricity gauge.

 

[Vern Kowalski]

I vote for the 21st Century Wheel Concentricity gauge.

Well that looks like one of the better gauges I've seen yet.

 

[Kosmic]

This one look amazing but $$$

 

[big boar]

BigEdP51, I use a Redding BODY die, then use a Forster bushing/bump die: 308 Win. I'm trying to see if using ammo that is "soft seated" will produce an advantage as I shoot Palma type competition. (300-1000 Prone). Because I use a "body die" (full body) would you then suggest a HORNADY comparator as the body really isn't touching the chamber? Thanks.

 

[bigedp51]

BigEdP51, I use a Redding BODY die, then use a Forster bushing/bump die: 308 Win. I'm trying to see if using ammo that is "soft seated" will produce an advantage as I shoot Palma type competition. (300-1000 Prone). Because I use a "body die" (full body) would you then suggest a HORNADY comparator as the body really isn't touching the chamber? Thanks.

A bushing die if the neck is reduced .004 or more will induce neck runout, and why many shooters who neck size get better results with the Lee collet die.

I'm sorry but too much of what benchrest shooters do filters down the average reloader and in not needed. Bushing dies work best with custom tight neck chambers and the average factory rifle will let the neck expand a lot more than .004. Meaning I do not have a high opinion of bushing dies because I get more neck runout than with a standard non-bushing full length die. The bushing floats and can move side to side and even tilt when reducing the neck diameter .004 or more and works best with tight neck chambers.

I'm 67 and have been reloading for over 47 years and discovered the Forster full length benchrest dies well after 40 years of reloading. And no other die I have ever used has produced as little neck runout as the Forster dies.

I decided to test different .223 dies below because I could buy then at a very good discount. The best die below for the lowest neck runout was the Forster full length benchrest die and the worst were the neck sizing dies. (excluding the Lee collet die) Also there are Redding, Lee and Lyman dies missing from this photo.

Also you can send the Forster dies back to them and they will hone the neck of the die to your desired diameter

So to answer you question, it depends if you have a custom chamber vs a factory chamber. And with a factory rifle I would not buy a expensive runout gauge and use the gauges I posted before. At the accurateshooter.com reloading forum more people use full length dies and Lapua brass and just load and shoot. I use my neck thickness gauge and runout gauge to setup the dies and once setup I see no reason to check each case. And I see no reason to use a body die follow by a neck sizing bushing die because the neck sizing die does not support the body of the case. Meaning a good standard full length die like the Forster die setup for minimum shoulder bump will produce the most concentric cases with a factory chamber.

 

[Mystic Precision]

BigEdP51, I use a Redding BODY die, then use a Forster bushing/bump die: 308 Win. I'm trying to see if using ammo that is "soft seated" will produce an advantage as I shoot Palma type competition. (300-1000 Prone). Because I use a "body die" (full body) would you then suggest a HORNADY comparator as the body really isn't touching the chamber? Thanks.

Consider measuring the change in dimensions from fireformed to body die.... vs Forster bump die. See which is a closer fit to your chamber.

308 reamers can vary in actual dimensions and so do dies... so I find it best to measure before and after to prove what is best for any particular set up. if you are using the forster die, why bother with the redding body die? The forster should take care of the shoulder bump AND the neck sizing.

If you mean 1 to 2 thou of neck tension, then you are spot on and that will lead to the lowest runout of a seated bullet. If you mean jamming the bullet into the lands when chambering, not something I would do given the times we have a cease fire and have to extract that rd.

The Palma type bullets can be tuned to be 5 to 10 thou OFF the lands so jamming is not a risk I would take...

YMMV

Jerry