Thoughts or Experience With This Concentricity Gauge

[Bill Norris]

That was on believe the target interview. Fclass john also did a video where he deliberately cocks the bullet sideway enough it is clearly visible on video. It didn't really make much difference on target.

Yes Sir, that is correct.

 

[jackieschmidt]

Because I don't have enough stress in my life, lol.

It's a rabbit hole I've always wanted to go down.

You will just have to take my word that the rabbit hole you are going down has been well used through the decades.

Quite a few years ago, Lester Bruno was selling this little contraption. You could check for roundup and then “straighten” the loaded round.
You could hear shooters in the loading area tapping away, trying to get things dead straight.
As hard as some hit, I often wondered how they knew if hey weren’t bending the bullet.
With my Rail Gun, I never could see the difference on the target between “zero” and .004 or so run out.
If your Dies are producing rounds with more than .004 runout, you might should critique your loading set up.

 

[Dave M.]

Concentricity Gauge

The price is right. Need to buy a gauge.

Thoughts?

They make an amazing paperweight for your desk. Good conversation piece as well. As for reloading, they are virtually useless and my best formed brass with virtually no runout, shot nearly identical at 600&1000 yards on the target. If it doesn’t improve your accuracy, there is no reason to bother measuring it.
Dave

 

[jackieschmidt]

I would think a machinist would tell you that rolling the case around and assuming the body is a perfect zero reference and a perfect circle accurate to 0.001" and it's rotating on a true centerline of the circle is ridiculous. If I had to guess I would think the run out on the body is around 0.001". Maybe that's good enough. The real rabbit hole is if you don't like the run out what do you do about it. Do you buy a new press and dies and hope it improves the run out. Guys on this website can tell you how they improve run out. I cannot. I shoot 2 accurate varmint rifles. I am not trying to win matches. The replies will be interesting and informative.

Food for thought.

If you have ever chucked a sizing die up and checked the bore with an indicator, many will have as much as .002 out of round. I suppose this is due to the case hardening procedure after finish machining.
If the case runs out .001 at that shoulder, it will be magnified as you go out further toward the bullet tip.

I am a machinist and we straight things all the time. Al be it somewhat larger than a rifle round.

 

[JFrank]

Concentricity Gauge

The price is right. Need to buy a gauge.

Thoughts?

The price is reasonable and hey, if a $55.00 investment in a tool gives you piece of mind that you are building good ammunition then its well worth the money.
Please report back on how you like it.
J

 

[Stud Duck]

I think I'm going to listen to the experience of the majority and find something else to spend my money on.

I appreciate all the replies.

 

[SKWERLZ]

That was on believe the target interview. Fclass john also did a video where he deliberately cocks the bullet sideway enough it is clearly visible on video. It didn't really make much difference on target.

It would be interesting to do a test with a precise F class chamber/barrel vs a generous factory barrel.

Years ago I separated 50 factory 5.56 rounds by runout at 5 and below and .006 and above and the result was a significant improvement in group size with the .005 and below.
Not scientific but I repeated it once more with same result.

 

[RabbitSlayer]

It would be interesting to do a test with a precise F class chamber/barrel vs a generous factory barrel.

Years ago I separated 50 factory 5.56 rounds by runout at 5 and below and .006 and above and the result was a significant improvement in group size with the .005 and below.
Not scientific but I repeated it once more with same result.

I think that could be true, especially a sloppy AR chamber.

 

[Dave M.]

It would be interesting to do a test with a precise F class chamber/barrel vs a generous factory barrel.

Years ago I separated 50 factory 5.56 rounds by runout at 5 and below and .006 and above and the result was a significant improvement in group size with the .005 and below.
Not scientific but I repeated it once more with same result.

Been there done that. It conducted this test with three separate F class rifles and there was no statistically significant difference between the ones with less than 2 thou of TIR versus the ones that had 4.5-7 thou of TIR (as measured at the top of the neck, not bullet tip).

 

[memilanuk]

Been there done that. It conducted this test with three separate F class rifles and there was no statistically significant difference between the ones with less than 2 thou of TIR versus the ones that had 4.5-7 thou of TIR (as measured at the top of the neck, not bullet tip).

Read it again. That's not what he suggested.

F-class - and other 'match' guns tend to have pretty tight freebore dimensions. .308 Win match chamber freebore is typically a half a thou (0.0005") over nominal bullet diameter; .223 Rem 'match' freebore is about two tenths over bullet diameter, according to prints. It's awfully hard for any bullet TIR to survive that and really influence things to any great degree.

Big, sloppy SAAMI chambers, where the freebore is quite a bit looser... going off memory here, but IIRC the .308 Win SAAMI freebore is more like 0.310". So there's a *whole* lot more opportunity for any potential misalignment to cause mischief.

Does it actually? Dunno. But what the previous poster suggested - test similar amounts of runout in *match* chambers against the same amount of runout in *SAAMI* chambers... that, I haven't seen a definitive test on. Seems like there'd have to be one out there, somewhere.

 

[JFrank]

I think I'm going to listen to the experience of the majority and find something else to spend my money on.

I appreciate all the replies.

There’s nothing wrong with consulting a concentricity gage when building quality ammunition, just don’t read too much into the results.

 

[searcher]

I think I'm going to listen to the experience of the majority and find something else to spend my money on.

I appreciate all the replies.

I think that is a good path. I have had several of similar gauges, the current being the Sinclaire model. Haven't used it in years.....

 

[R.Morehouse]

Looking at the unit for sale, I think it will do what you want. If you find out in the future that it isn't for you, it will look cool sitting on a desk or maybe your shelf of forgotten toys.....

Regards
Rick

 

[Alex Wheeler]

With that design, the rollers have to be perfect to not ad to the runout reading. The first thing I would do if I bought the one is spin a ground rod t make sure the rollers were round and the holes in them centered. The non rollers designs are fool proof.

 

[cptjack]

since I started to use mandrels no need loads cone out very concentric

 

[L.Sherm]

Spend your money on inline seating dies and a press its money well spent.

 

[BoydAllen]

First of all I want to admit that none of my concentricity gauges cost me a dime. Currently I have three, one that straightens. I like knowing what a given piece of equipment does to my brass, and loaded ammunition.

Years ago, using my H&H gauge, that supports a round near the head and the tip of the bullet, that I have set up to read runout where it shows the largest reading for a given round... I used the straightening feature to bend a round so that it had about .0035 runout, chambered the round and then measured the runout at about .0015.

For those that have the money, if you want the straightest possible brass, there are two options, use a one piece die that has the neck ID that produces the neck tension that you want without additional work, or use a SAC bushing. Recently I have ordered a couple of these for a friend and sized a few of my own cases before he picked them up. They are amazing. On the one piece die thing, I have a Hornady (the cheapest 6PPC die that they make) that produces neck OD of .257. The runout at the end of the case neck, measured with my Sinclair gauge, is under .0005.

In benchrest, there are things that we know produce greater accuracy, and some that we do on the chance that they do, or simply to have more confidence in our ammunition.

Years ago. my first gauge told me that my one piece RCBS FL sizer was mangling my brass. I learned that it was straighter if I pulled the decapping assembly and expanded the over sized necks with the expander die and mandrel that I got to use with my neck turner.

Learning about the differences in die performance at that level was useful. Later on, I occasionally was surprised to find that some whiz bang piece of supposedly top end equipment did not perform as expected, but most did. I would not be without one, but the ones that I have only come out of the drawer when I need to find the source of a problem or evaluate a piece of equipment.

 

[rwj]

With that design, the rollers have to be perfect to not ad to the runout reading. The first thing I would do if I bought the one is spin a ground rod t make sure the rollers were round and the holes in them centered. The non rollers designs are fool proof.

Even with “V” block designs, case ovality will appear as runout…

 

[Laurie]

but the ones that I have only come out of the drawer when I need to find the source of a problem or evaluate a piece of equipment.

The sole benefit of this tool IMO.

 

[Webster]

It would be interesting to do a test with a precise F class chamber/barrel vs a generous factory barrel.

Years ago I separated 50 factory 5.56 rounds by runout at 5 and below and .006 and above and the result was a significant improvement in group size with the .005 and below.
Not scientific but I repeated it once more with same result.

You don't give up. Some of the best shooters in the USA are giving their opinion on this post. Believe what they say.