??Fixing Concentricity

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docsleepy

Guest
I'm a beginner, and don't know much about concentricity.

On a nearby thread, a participant wrote

VaniB: My results with the Hornady Concentricity Gauge Tool are a mirror image of yours. Recently put together 80 newly formed 6ppc from Lapua 220 Russian, outside neck turned to .013" for my .272" chamber necks. Turned them all under the Sinclair Concentricity gauge, and took the worst single example of runout, at .007". This does not bother me, since I know it will straighten out with the first firing. (emphasis mine)

Another writer indicated that merely chambering rounds in a tight chamber would fix concentricity problems....

This leaves me quite puzzled: (I use a Wilson inline seater, but don't have a concentricity gage except for a crude one that I made...considering buying one)
1. Does this mean that necks with runout will be FIXED by firing and then have only the usual risk of developing runout? (so, don't throw them away, just use them for foulers)
2. Does this mean that the biggest advantage is merely to identify which rounds you should NOT use for record shots? (so, I should buy the gauge and use it)
3. Or does this mean that if you have a tight neck, crooked necks are not as important--the chamber will fix them before you pull the trigger? (so, maybe I don't need the gauge at all?)
 
concintricity

docsleepy: I'm the one posting the msg. to vanib, and what I meant when I said that initial runout with never fired brass does not bother me: I know the brass will fireform to my chambers dimensions, so the runout that was introduced when necking up 220 Lapua Russian brass to 6mm, pushing back the shoulder a small amount, and outside neck turning, (all putting stresses on the brass causing runout) will correct itself with the first firing. The vast majority of those 80 cases have been fireformed now, with 2 to 3 loadings on each, and runouts are all a maximum of .002" with most being around .001". If I identify a case that consistantly has excess runout, after 2 or 3 loadings, at the most, it will be marked and kept for less demanding use. To me, that particular case has a defect maybe from when it was drawn, and it will never straighten out. I have several tight, fitted neck chambers (6BR's with .265", 6ppc with .272", 22 BR with .251"), and runout rounds are used in those chambers the same as my tight no-turn chambers, for "limited" use only.
 
The best use of a concentricity gauge is to monitor what your dies are producing. The other variable that produces runout is variation of case wall thickness, around the body of the case. As always, being able to measure what is going on is better than not. For cases and loaded the Sinclair is good, for loaded and straightening I would go to the H&H.
 
Thanks, guys, for that information. I understand it better now!
Gordon
 
Doc,

Some guys on these boards claim that they handload well enough that they don't need a concentricity gage. They say it's all in your technique. If you're good like them, you need not take the time to even bother checking the finished round. Gosh, I hope I grow up to be like them.

Not being in their league, I'm not sure if I can provide a qualified opinion. I shoot 5 shot 1/4 - 1/2" groups in my Remington action varmint rifles pretty regularly with what I handload, but darn it that I have to deliberately work at producing such cartridges. I'm just not as good as these fellas. So, until I grow up some day, I'll have to keep relying on this amateur stuff like concentricity gages to check how I'm doing. Heck, I'm surprised Sinclair hasn't discontinued them for lack of sales!

My rifles are obviously amateur stuff too, as I have never found the chambers to automatically straighten the bullet tip 3 or 4,000ths of an inch one way or the other. Damn this having to waste time hand tailoring and checking my finished work. Why can't I be like them!?!


20Tactarget.jpg


20Tactical_edited-1.jpg


22X47L1sttargetusingMB.jpg
 
Vani B

Not all volkswagons get 40 mpg and not all dies load exceptionally
straight, even from the same manufacturer. Bushings are often
other than true and the tops of bushing dies weigh in with a great
affect. As Boyd Allen and others have said, using the concentricity
guages to sort out die problems is the key. Once they are correct
the concentricity guage can be put back on the shelf. I use
special V-block jigs to sort out dies and bushing problems and
a special concentricity guage to check seating. Straightening
loaded ammo is time consuming and even questionable. My
current PPC ammo runs about .0004 on the average
 
Wow. You guys are big time convincing me to get one.
Appreciate the education!

Thanks,
gordon
 
Darn Bob, that's really good! Run me through what you have done to get that kind of result. Seriously, your results are significantly better than mine. Been tuning up that seater stem cavity...making custom one piece dies...custom bushings...VooDoo?

About straightening from chambering....On my 6PPC barrels, I have a neck to loaded round clearance of around .001 or less, depending on the pressure ring diameter of the bullet that I am loading, and I am into the rifling an appreciable aamount, and crooked rounds will straighten. One time, I intentionally "crookeded" a round to .004 or .005 misusing my H&H and then I chambered and remeasured the round. It was .0015 on the bullet, the upper limit. On the other hand, with a factory chamber, with a .006 to .007 neck clearance, I would not expect the same result. BTW straightening thick necked rounds that have a lot of neck tension and were loaded with bullets with no pressure rings, is a real PITA and of questionable value.
 
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As for the straightness of rounds being directly related to your skill in reloading. Does that mean as you spend more years reloading, your round becomes more concentric? Should you hold your tongue just right when seating bullets, face mecca when sizing, or maybe get a Feng Shui master in to set up your reloading room? Maybe it will help if all planets are in alignment when you set up your sizer.
 
Improving load quality can be as simple as selecting the best tools for job & operating them correctly. In the case of doc’s factory or hybrid rifle, which is liable to be running generous factory or SAAMI spec chambers, the game will be won once the case is prepped to take the next load. It’s no use using any die that pulls a ball back thru the sized neck, if for no other reason that the case rim isn’t being held around 360 degrees of its circumference. Likewise, bushing dies won’t necessarily size down a factory neck to the necessary diameter to hold the projectile in one step without running the risk of sizing crookedly or off to one side. Check our what Redding has to say on this. Bushings work perfectly on close tolerance chambers particularly when the die is made to suit that chamber. Full length sizing brass much beyond what’s necessary to achieve a bolt closure without drag or baulk is bound to leave cases lying on the bottom of a roomy chamber & the projectile angled in the throat.

On the other hand, the Lee Collet die operates by aligning a mandrel concentric with the case (the primer pocket, but that’s the same thing if you use Lapua brass like I do) & ironing the case neck against that mandrel. John Valentine has had a fair bit to say about this die on the BR Central forum (see http://benchrest.com/forums/showthread.php?t=49899) & I totally agree with the efficiency of this system to obtain correct neck alignment & thus straight reloads. I shoot quite a bit at 1200 yards with the .308 Winchester using 200-210 grain projectiles loaded out to an average of 3.1” OAL. Once prepped with the Lee die, I can seat the big pills on mildly compressed loads 9just a pat on the head really) with either my Forster Micrometer seater or my Wilson SS micrometer seater & get very little run out even when measured as far forward on the ogive as I can find a smooth surface.

An extra benefit of this die is that because it doesn't drag a ball thru the neck nor iron down the neck, but instead gently closes & releases square to the neck, I find very little need to size the case body, Likewise, I find very little growth in the case length over multiple firings.

The Lee die isn’t top shelf stuff; it’s about as inexpensive a tool as you’ll find in a gun shop, but used correctly, it works.
 
Boyd Allen said:
Darn Bob, that's really good! Run me through what you have done to get that kind of result. Seriously, your results are significantly better than mine. Been tuning up that seater stem cavity...making custom one piece dies...custom bushings...VooDoo?
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You see that gentlemen. Until you grow up and become "one of the guys" you still can't get the credit. :D

Vanib,

(aka Bob, Jim, Steve....)
 
John Kielly said:
On the other hand, the Lee Collet die operates by aligning a mandrel concentric with the case (the primer pocket, but that’s the same thing if you use Lapua brass like I do) & ironing the case neck against that mandrel. John Valentine has had a fair bit to say about this die on the BR Central forum (see http://benchrest.com/forums/showthread.php?t=49899) & I totally agree with the efficiency of this system to obtain correct neck alignment & thus straight reloads. I shoot quite a bit at 1200 yards with the .308 Winchester using 200-210 grain projectiles loaded out to an average of 3.1” OAL. Once prepped with the Lee die, I can seat the big pills on mildly compressed loads 9just a pat on the head really) with either my Forster Micrometer seater or my Wilson SS micrometer seater & get very little run out even when measured as far forward on the ogive as I can find a smooth surface.
.
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Funny you should write that!
I am still using a Lee collet, although I bought a Harrell die but don't have the bushings for it yet. I'm using a .270 (Shilen) neck, and since I'm quite new to this, I have some variation in my loaded-rounds-diameter, but I shoot for .268
I tried to MAKE a concentricity gauge, using an indicator, a vblock, some wood, and a long 1/4" bolt on which I could move the indicator back and forth; not very sturdy, however. Based on the comments here, I'm going to get the Sinclair one (I run myself on a budget, so it will be this weekend before I allow the NEXT purchase....seems like something gets bought every single week....better scope next?).
Thanks for the reference on the Lee -- I'll read it.
Thanks for all the incredible info, gang!
 
John -- went and re-read the entire thread. Pretty sure I had read much of it once before. Thanks again for the point-out.
Do you know if Lee will make custom THICKER mandrels, if I want LESS neck tension? Or thinner if I want more?
 
When I changed to moly coated bullets for a while in my Swift I found that the neck tension with stock mandrel was too little to keep the coated bullets secure, even though it had been enough to work with uncoated bullets. A call to Lee Precision solved the problem. They shipped me one that was .001 smaller. I doubt that you will need to go larger, but they probably would do that as well.
 
You see that gentlemen. Until you grow up and become "one of the guys" you still can't get the credit.

Vanib,
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alinwa said:
Actually credit is just like at the bank, you've got to earn it.

al
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You know Al, I saw your name on the main page to see that you had added a comment following my post. Why did I know that before I would even go in here to read what you had to say, that it would be arrogant and condescending? :( You ARE just the kind of person that I have been facetiously referring to in my first post.

Gentlemen, when I opened a thread last year to try to show off the newly completed glass-slick finish on my 22x47L rifle (which fired the target in the last photo above) I had offered to share the finish teqnique with others if they were interested. (because I was so pleased with my results after a week of working at it). Well, Al had the audacity to provide nothing but criticism that the glass-slick finish looked like crap, and that I should be aware that BRCentral wasn't the kind of place to come looking for approval from others here if it wasn't deserved.

On this thread, unless I'm totally misunderstanding something, Boyd Allen was complimenting me on those targets I had posted. It was very flattering for me to read what he had to say. But he called me "Bob" in error, and so I joked about it like it was part of a Rodney Dangerfield routine "See, I don't get no Respect." Frankly, as long as that Boyd Allens post above was addressed to "Bob" I can't really be sure that it was intended for me. But, if it was for me, I would certainly be humble enough to thank him for the kind words. :)

Where as I did not mention anybody by name concerning some of the arrogance that is found on these boards, Al came here to do nothing more then belittle and berate me some more and let me know that I better keep working at it if I wish to "earn" his respect.....as evidently he hasn't seen or heard anything from me yet that is worth his approval.

Guys, I will not mention anybody by name, but boy there sure are some pompous asses on these boards who would do well to learn the meaning of grace.

Randall
 
doc,

Lee will make a die for a particular calibre at a price - or so their site said a year or two back - so I would guess that they could make oversize mandrels. However, according to their claims in their reloading book, you wouldn't be likely to want less tension anyway.

As far as thinner mandrels go, I have quite a few for my .308, salvaged from the guys who decided they needed brute strength to do the job. They spin fine in the average bench drill jacobs chuck with the flange in the slot in the jaws of the chuck. I dressed them down in .001" increments with 600 wet & dry hand held running at about 800 revs & polish with 1000 or 1200, whatever's around. I salvaged the lock nuts too to put on my body dies so I can twesk them just right when I'm shoulder bumping.

I also made one with a short pin - too short to touch the primer at full throw for those mind fart occasions when I prime the cases before neck sizing them.

John
 
al,

Aren't you being a little tough on Vani? After all, this is the Factory & Hybrid forum, so maybe people can be fed a little more slack than, say, the Competition Benchrest forum. Sure he acted like a comprehensively unnecessarily nasty tosser (as we say in Australia) in the preamble of his posting, but can't the group shots be taken at face value? It's not as if somebody with any factory gun is going to front up at a BR match to prove his claims and there aren't (m)any credible disciplines that would allow him to gain the necessary grouping cred.

Guys like me who shoot F class have rifles that can do some mean work but I can't offer anything to prove that either - score matches don't record groups. Now & again, I put down a passable 1000 yard light gun BR shoot, but I'm overcommitted & miss too many shoots to call on those results. Does that mean that Vani's right, that anybody who doesn't shoot 100/200 yard benchrest can't expect any credence on this site?

John
 
Boyd Allen said:
I doubt that you will need to go larger, but they probably would do that as well.
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That's educational to me -- thanks ! -- I was afraid I had too much tension. I'm used to seating in a lee press (barely touch it and they are seated), and when I got a K&M (3" handle) using a Wilson seating FB bullets -- WOW!! that was a completely different feel! I calculated I had .002 tension. The brass is slightly work hardened by now, springs back a bit more, and bullets seat with less fright on my part.

Still plan on getting the concentricity gauge to check, however.
 
docsleepy said:
Still plan on getting the concentricity gauge to check, however.
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Can't argue with that, even if both of mine are gathering dust. At least I have backup dial gauges. :)

Be prepared to doubt you competence with them, though. None I have ever handled were foolproof easy to use & more than once, I've rolled rounds down a glass table to verify the gauge reading, one way or the other. It takes a bit of thought to decide what & where to measure so you can positively isolate what's out of whack & what's not broken anyway.
 
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