Concentricity gauge

[gspn]

Who would benefit from using one? I'm guessing that a concentricity gauge becomes more useful the longer the shot you're taking…but this is just my guess as I've never used one.

I don't shoot in competitions, I hunt. The ammo I make is entirely sufficient for the ranges at which I hunt. But I wonder, would I see a material reduction in group size if I were to use a concentricity gauge? Do all groups benefit from the use of this gauge?

 

[savanahsdad]

lots of things can give you bad groups , a burr or bad crown , a bad batch of bullets , a loose scope, a bad scope , over all bad hand loads , like bad powder , bad primers ect ,ect , and bullet run out and you need tools to find out why you are getting bad groups , I have two concentricity gauges a Holland & Holland and a Bonaza I check my first two rounds and the just a few more at random as long as they're under .005 I'm happy if they're over that then I start checking my brass , if the brass is over .0025 they get set aside , if I'm getting bad groups there nice to have so I can check for bullet run out , other wise you're just guessing , some guys use them for peace of mind and others who have been loading for 30+ years have never owned one , so are they needed ? no , but they're nice to have

 

[Mohave-Tec]

Sometimes you just have a question that can't be answered any other way than by using a concentricity gauge. I used one yesterday not only to check neck center on some FL sized 308 cases but to fortify my suspicions for colette center in a new die I chucked up. I also use a concentricity gauge to help decide how close to the lands I'm going to try to load a bullet into a case. I am very pleased to announce, in fact, that my new RCBS standard FL sizing die is pulling cases that were .009 out of round in the neck back to only .001 out. My chamber is 2.914 deep and with this nicely centered neck I can dare to seat to as close as 2.912 inches. With uniform wall thickness in the neck (which my concentricity gauge will also measure) nothing else will give you this information.

 

[scottishkat]

I find the concentricity guage handy for checking dies as well as run out. Check the brass before you resize then run your brass through the sized without the decapping rod then do the same with the decapping rod. Check them at each step and you can identify problems with decapping rods etc.

The more you get into the more myopic it gets though. If you have full length, neck sizers and body dies you can check which is performing best on your particular cartridge.

I really like the Sinclair unit I purchased about 5 yers back. I am pretty anal about brass though. It is one of the items we can control. Can't do much about powder and firearms. Bullets we can sort, brass we can correct to some extent, primers we can change.

Good luck and shoot straight

Bob

 

[Walkalong]

They are the only way to know if your dies are worth the money you paid for them, whether it was $19.95 or $79.95.

I bought a NECO years ago. I would probably go with a Sinclair these days.

 

[RAT807]

I have the Hornady gauge and was able to find my decapping stem threads were damaged and had to be replaced. On a whimp, I spun the new stem on the gauge and to my surprise it was not straight. So far all loaded rounds using this die now have at most .002 rollout.

9mm rounds are too short to roll on the gauge so I started rolling them on the bench. Shooting groups at 25 yards, it's easy to tell the straight cases from the ones that do not roll straight.

 

[GW Staar]

Here's a good example of testing a die's ability to make concentric brass or rounds. You can lose the battle for accuracy all along the way, starting when you pull the expander out and it moves the shoulder .005" or more out.....or when you seat your bullets, and that process adds another .005" out. These tools make it so you can see the problem areas and deal with them, from using better lube practices and/or sizers, to using better seaters.

http://www.youtube.com/watch?v=RZEas38vkKg

I have the tool depicted in the youtube video. That RCBS tool is more versatile in that it allows for more measurements (including wall thickness in necks and body), but the "V" blocks are not so high tech. The aluminum isn't the smoothest around, but it does work. I really like the Sinclair ball bearing unit Walkalong linked to in his post......the bearings make it easier to use and it doesn't scuff your brass as you rotate it in the tool. I've never used one so I'm assuming a little, based in my experience with the RCBS tool......cheaper too.....but to be fair it only measures case and bullet runout.

 

[spitballer]

For what it's worth I think I would spend the money on a neck turning tool and something to measure wall thickness.

 

[Walkalong]

Oh, they'll likely end up with those as well. Just kind of works that way with us curious sorts.

 

[scottishkat]

I ended up with those as well the more into you get the more myopic. Its all part of the reloading process. The bearings on the sinclair unit are nicer than the RCBS unit I have used both. The bearings will let you know when they need oil with a little scratch though.

Good luck and shoot stright

Bob

 

[kelbro]

Concentricity gauges are VERY expensive. After using one, you will throw a way perfectly good brass. You'll buy several sets of dies until you get the right set. You'll buy neck turners, inside reamers, and all sorts of gauges and micrometers.

 

[GW Staar]

You're forgetting mic-topped seaters, special mandrel/expander dies, collet dies......give up....you will be assimilated.

I think the best sizers on the planet are probably simple RCBS sizers, with the expanders taken out, and the necks lapped to .002" under a finished bulleted round (courtesy education from Bart B.). But those require attention from a good Smith.....more mon. I'm too cheap for that.......so far.

Of course such require reaming inside.....so there's the reamers.

 

[Rule3]

I know little to nothing about these gauges. I understand the concept.

I watched the video. Although it's nice to see a LEE product do so well is it really a statistical valid test????

Only 3 pieces of brass and the dies are different types, a neck sizer vs a FLS.??
Please the FLS brass still had lube on it if that matters,

Anyway, so you gauge the brass, says it's way off, what do you do then is the question??

 

[Walkalong]

You're forgetting mic-topped seaters, special mandrel/expander dies, collet dies......give up....you will be assimilated.

I think the best sizers on the planet are probably simple RCBS sizers, with the expanders taken out, and the necks lapped to .002" under a finished bulleted round (courtesy education from Bart B.). But those require attention from a good Smith.....more mon. I'm too cheap for that.......so far.

Of course such require reaming inside.....so there's the reamers.

Forster will perform this service on the sizer dies. You need to have it done for a certain neck wall thickness. ("the necks lapped to .002" under a finished bulleted round") Your brass.

Much thinner or thicker will neck walls will naturally change the neck tension you are aiming for.

 

[Rule3]

OK I'll try again.

What do you do if the case necks are not concentric and vary a lot on the gauge?

 

[GW Staar]

OK I'll try again.

What do you do if the case necks are not concentric and vary a lot on the gauge?

So many choices!

1. Try better lube...make sure the expander rod is tight & doesn't flex. The object is to not have excess pulling and stretching on the neck and shoulder. I have even tried (successfully) to resize two more times rotating the brass a third....it works...(almost all I tried to .001) unfortunately, it also work hardens the brass shortening it's life. I'm guessing that works because the expander rod flexes less each time it gets easier to pull though? In my recent experience I found that an RCBS lube pad and neck brush works better than Imperial (no contest even) if you have hard to size brass......my latest trial was 2013 LC 7.62 brass (from Wideners)! Now I know why most stuck cases removed by RCBS (according to them) had wax-based lube inside.......geeze I have used a lot of Imperial, but my necks are straighter using the old stuff. Somebody says STP/Hoppes #9 mix is even better?????? Haven't tried that.

2. Take the evil expander ball out and try it without. If that make brass perfect or .001" or so....then maybe try a Sinclair Expander with mandrel:

3. Or just lap your sizer until it is .002" under the bullet size. Then you don't have to expand at all......but you need a separate lapped sizer for each kind of brass because wall thickness varies by brand. Walkalong just said Forster laps them for a price........I didn't know that!

4. Or use a bushing die....again bushings also have to be sized by brass type.

If that doesn't confuse you then know that as soon as you seat a bullet the round goes sckewed again, or some more. That's why those expensive Redding, Forster, and RCBS Gold Medal seaters are populer with many.....they seat straighter.

And finally the Benchrest sizers and seater that use an Arbor Press and neck sizing............except neck sizing is losing followers in that group these days as that group are starting to return to full length sizers. Still confused.....welcome to the club.

 

[Rule3]

Thanks. So I am better off not knowing

I use the LEE neck sizer dies on my bolt action guns and my ammo is accurate enough for me. I am not winning prize money or Medals so I am not to concerned.

 

[GW Staar]

Thanks. So I am better off not knowing

I use the LEE neck sizer dies on my bolt action guns and my ammo is accurate enough for me. I am not winning prize money or Medals so I am not to concerned.

That would have been my answer a couple of years ago......like I said, you will be assimilated. It starts when you buy one of the damned things......and you will for some reason or another.

Then you gotta decide whether the ones that measure from the case or cartridge center line is better, or one with a case rolling over a v groove or bearings. That'll start an argument......I've decided that you have to have both.

Gotta tell you, I was "concerned" because neither my Rock Chucker nor my Summit (in trying to create a comparison review between presses for the forum) would make that RCBS needle stay put....even with the expander rod out. Never got better than .001"!!

Then I realize 2 things: 1. the LC brass I'm comparing with varies that much in wall thickness!.....so rolling in on top of the "v" groove reflects that in needle movement!! and 2. Do you realize how much .001" is? 1/3 the thickness of a sticky note! Doh! Only benchresters care. But hey, I love to learn new things and will 'til I'm dead.

 

[Mohave-Tec]

Rule3, I insist on using dies that pull my cases into proper round. I just bought a new RCBS standard 308 die and pulled 30 cases of 308 that were .008 out of round and every one of them came back to being only .001 out. That is pretty exceptional. That translates into the outside of the neck being within 1/1000 inch of being centered over the main case body. If the wall thickness of the neck is the same throughout the circumference under these circumstances then a bullet will jump straight into the rifling just after the chamber. This is how concentricity relates to cartridge re manufacture. If the load is truly concentric then you can start experimenting with chamber depths or, for clarity, how much shallower you can seat a bullet to bring it closer to the lands (first contact with the rifling) if being closer to the lands proves to create a more accurate load for your particular rifle. Many feel like their bullets are at their best when the bullet only has to bridge a gap of about .002 inches before contacting the rifling. It is very much best if the reload is concentric if it has no place to go but straight in. LOL.
Of course this is a over simplified explanation.

 

[Rule3]

As I mentioned in post #13, I use the LEE neck size dies in my bolt rifles. Even though I do not think that video is a truly valid test. I will take it as such and I saw it on the internet, so it must be true!.

I'm good.

I suppose after getting the gauge I will need one of these which I just saw on another forum.

Totally useless piece of expensive equipment to me.

Holland Perfect Primer Seater

http://sierrabullets.wordpress.com/2014/03/19/tools-of-the-trade-hollands-perfect-primer-seater/

 

[Mohave-Tec]

You'll require 2. One for both sides of the primer.

 

[GW Staar]

When that's required I will quit reloading.

I did buy an RCBS concentricity gauge, mostly because I wanted to test the new Summit Press against the RCBS Rock Chucker. I had no idea I'd have to relearn everything I know about reloading to use it properly.....in a week. I am learning a lot though.......I just don't know if it will be retained much past next month. Bart B. and Uncle Nick over at the Firing Line are trying (patiently I might add) to teach an old dog new tricks. We will soon see if they ban me from that forum for ever. Do look in though if you are just a tad curious.
http://thefiringline.com/forums/showthread.php?p=5798782#post5798782 I'm the dummy GWS, there.

Mohave-Tec: BTW in Post 17 there Uncle Nick talks about "the" John Feamster who wrote The Precision Shooting Reloading Guide who found RCBS regular seating dies in a Dillon 550 can sometimes outdo Wilson benchrest seaters in an arbor press!!! In this hobby nothing's set in stone.

 

[Mohave-Tec]

I don't get too uptight about precision shooting anymore. I can't see well enough for 1000 yards these days and I wouldn't have a clue if my pistol rounds are better or worse. But it is a snap to use a dial indicator to see if you (everybody/anybody/ no particular body) are introducing slop into a round and if your equipment needs attention.
I also check chamber depths. You'd be amazed at how much difference there is there too, for the same round.
.......
I read the other thread. It is beneficial to take ever aspect as far as it can go. The more I do the more I understand but these days I just want to know if I'm within .003 (a common tolerance in heavy industrial machinery that I've work with for years) rather than blindly working at say .01 out on every occasion and not knowing it. Measuring this way will fix many wrongs without having to be too concerned whether you have bearings or a flat surface for turning an axis in a concentricity gauge.
BTW, the other read was an interesting read. It gives me so ideas and made me aware of a couple things I had not thought of before.