I was wondering how important a concentricity gauge is? Could someone explain the benefits of using this piece of equipment?

Hvy barrel, What are you wanting to check with the concentricy gague?

If you're planning on checking the necks on your brass, then you'll probably be horrified by the results. If you're planning on neck turning your brass, then a concentricy gague would be good to have to check/ verify your results, but wouldn't be necessary.

You might also think about asking this question in the bench rest forum.

mike

The H&H Industries Concentricity Gauage Will allow you to reduce your loaded round runout. Yes, I have had one for about 2 weeks and whould not be without one. I have redued my groups by half. You can center the bullet to within + or - 0.0005. After useing the gauage on my 6.5 BR rounds I shot the best I have every.
H&H Industries,PO Box 763, Albany,OR 97321 Pnone US (541) 327 1411,E-mail "HANDHIND@MSN.com" Do a search on H&H. Twyman

I`ve a RCBS gage. I don`t see that it matters for ammo used at 200 yd or so. The thing has affected my sleep more then my groups...

Hvy, It depends on what you want to do. You will almost always find new brass is way out, but once fired, maybe twice, it should be damn good as it comes out of your chamber. I personally think that a gauge is invaluable when setting up dies and getting a set that will resize and seat bullets while keeping the runout to an absolute minimum. I have found that commercial dies [of which Wilson seems to be the best] are, for some reason prone to having more runout than I care for. I have ended up making up a sizing die for every ctg. that I shoot out of a Newlon die blank [neck sizes only] that I have chambered with the same reamer that I did the barrel with. I have found it necessary to make up a seater for most of my ctgs. but get away with a couple of Wilson seaters. Once you have your dies working the way you want them, I only use my gauge now and then to make sure nothing has craped out on me. My loads that are important to me [30BR, 30X47, .308, and one of my own design] will load with the vast majority under .0005 runout, occasionally ony a bit more but never over .001. As you can see I think a gauge is invaluable. A concentricity gauge will tell you nothing of any value on a new piece of brass or one that5 has just been neck turned.

quote:

Originally posted by cndrm:


If you're planning on checking the necks on your brass, then you'll probably be horrified by the results.
mike

Measuring case necks with a concentricity guage is mostly a waste of time.
Most unturned brass has variation in the thickness at the neck ( as in a thick side and a thin side ).
If you use an expander ball you will see this as variation as runout at the neck.
If you do not use an expander ball you will see less runout at the neck in brass with case neck variations.

It's a cruel illusion that the runout is better without the expander , the variation is still there , except it has been moved to the inside of the neck.

The inside is more important than the outside.

Concentricity is a good thing as far as the actual bullet being straight . measure at the bullet.


Travis F.

lyne

What was the cost on the H&H gauge?

The cost of the H&H Industrics gauage is $150. It is worth every penny. My was S/N 164.

TBF, I don't know if concentricy is more important on the inside than the outside. Yes, it's obviously important for the bullet to go in straight, but is it not equally important for the case to expand away from the bullet evenly durring fireing? If the case is thicker on one side, then I can't expand out as far as on a thin side, and may not even clear all the way from the bullet.

Personally, I neck turn my brass, and use a concentricy gague to check every few rounds to verify proper function. (on my part as much as the equipment).

mike

cndrm, a concentricity gauge will tell you nothing on a new or newly neck turned case. The only tool that is needed while turning is a uni-micrometer, the walls of the neck should be as close to evenly thick as possible. A gauge that you are asking about is only of value after a case has been fired and the chamber has had a chance to streighten out the cases neck. If you do not believe this run a new case through a gauge, run it through after it has been loaded, and one more time after it has been fired. The case should then be as true as your chamber,occasionally it will take two fireings to get it as streight as it is going to get. If after a couple of fireings your case is still not true there is a chance that your chamber neck is not streight, but this is a rare occurance. If a case is good after fireing,then check it after each reloading step and you can see if and when it craps out on you. I believe that I have an extra uni-mic that you need to neck turn, if you do not already have one and email me I will send it to you. As I say I THINK I have an extra. Believe me one is needed. In a properly neck turned case the run out should be the same on the inside and outside of the neck. I have not got to the point that some guys say that they have in obtaining a perfectly uniforn case neck, but I can generally keep them within 2 or 3 tenths. I honestly question these people as I take as much care in turning as possible and as I say do not end up with perfect necks. I preload for 21 different barrels and have about 2800 pieces of brass that I have turned. Good luck and give what I suggest a shot when you have a few extra minutes, I think it will surprise you.

lyne,

Does this tool allow you to "straighten up" a bullet that is seated crooked?

Jim

Yes, I have Straighten up ammo seated crooked of .009 to .0005. Here is a picture.
http://divacatdesign.com/images/straightner.JPG
Results of a Ecore T/C Custom shop barrel with bad chamber and 3 lb trigger:
http://divacatdesign.com/images/results2.JPG (target dots are 3/4")
We did tests and it reduced our group sizes 1/2.

quote:

Originally posted by cndrm:
TBF, I don't know if concentricy is more important on the inside than the outside. Yes, it's obviously important for the bullet to go in straight, but is it not equally important for the case to expand away from the bullet evenly durring fireing? If the case is thicker on one side, then I can't expand out as far as on a thin side, and may not even clear all the way from the bullet.

Personally, I neck turn my brass, and use a concentricy gague to check every few rounds to verify proper function. (on my part as much as the equipment).

mike

Mike,

I have no definitive answer as to which area would be most inportant . My guess is that the case neck inside would be more important than the outside because this is what contacts the bullet and determines bullet pull , bullet placement within the chamber ( any offset will be away from center if the bullet is not in contact with the lands ), and also generally ( IMHO ) would be benificial to consistancy issues in general.

This , of course assumes that there is a difference in neck thickness , turned necks should be pretty close to not having any variance , in theory ...
Standard , consumer grade brass often will show variance .
I think you are correct about uneven expansion , this makes sense . I would assume that the more variation present , the more uneven this expansion would be.

For the factory rifles I have measured , there is plenty of room for the thickest , most uneven brass to clear the bullet with room to spare. This may not be true on tight neck custom stuff . I hear tales of tight neck chambers on bench guns that do not require neck sizing after firing , and require neck turning to a specific dimension to function properly .

My most recent 300WSM project has a factory chamber neck that allows unturned Win. brass to expand a little more than I would like it to , requiring a two step neck sizing with my Redding "S" dies to avoid tweaking the neck.
Turning brass for such a chamber may make things worse as there would be even more sizing required to get the neck ID dimension correct. More sizing can cause concentricity issues , .003 - .004 is pretty much all I can reduce in a single step without adding more runout.

YMMV on all of this , just .02


Travis F.

quote:

Originally posted by Ol` Joe:
I`ve a RCBS gage. I don`t see that it matters for ammo used at 200 yd or so. The thing has affected my sleep more then my groups...

Amen- A concentricity gauge is guaranteed to drive you absolutely insane!

It seems as though it would make more sense for the gentlemen that are getting large amounts of runout to put their effort into a set of dies that will load ctgs. that are streight, then to streightening them after they are improperly loaded.

I think that before you guys get to far ahead of yourself in condemning the Bersin and other runout adjusters you should actually try one. Even with an extensive set of reloading tools you can still get more runout that you want. I've noticably reduced group sizes by using the Bersin tool. And this is after very carefull reloading including the use of "Benchrest" or "Competition" die sets, neck turning etc. etc. etc..
But again before you say something isn't worth having or using you should actually use one enough to really know what you're talking about. You certainly make a valid point that you should try and adjust your reloading techniques to reduce runout as much as possible but please realize that a runout adjuster can compliment your techniques by reducing runout even further..............DJ

Reducing run-out will definietly reduce your group sizes a good deal if you are shooting paper or longer range hunting. I've dramatically reduced my groups since I started to straighten my rounds.

On my paper punchers, I like .0005-.002 and on my hunting rifles I like less than .003.

I you really want to see some run-out, check some factory loaded rounds

I will say the Lee collet dies produce some pretty straight rounds.

On the straightening note, I straighten my rounds by hand. It's quite easy and only takes seconds. I mark the high spot on the brass while on the runout gauge w/ a fine point sharpie. I then place an old once fired brass on the bullet and slide it down til' the case mouths touch. I place alittle pressure in the direction the bullet needs to go and then roll it on the case gauge again. Very simple but, don't think you'll master it on the first go, it takes a few trys to get the "feel" down. Be careful that you don't put too much pressure and go too far, if you wiggle it bakc and forth you'll loose your neck tension. I've straightened hundreds of rounds w/ that method w/o any problems and they shoot really well.

Last time we spoke of this someone said they drilled holes in a block of wood and used them for straightening. Probably a better approach then what I'm doing, I just haven't gotten around to making a block yet. Maybe I'll try some oak and give her a whirl.

Good Luck

Reloader