Here we go. An article in the February 2004 issue of Precision Shooting about these legendary gunsmiths struck a sour note on some of the points brought out by the author. Before I get too deep, let me say one thing, the author is getting paid to write and the editor edits for subscriber readability.

These are some of the finest accuracy gunsmiths I have had the pleasure of knowing of. I have not met them personally, but have heard of and/or talked to them. Believe me, I do not put myself in their league.

Toward the middle of the article, they are asked to describe their method of chambering. This runs the gamut of procedures, all good. The question I have is, is there a typo when referring to the extent at which they strive for runout accuracy? The article states, in one, "....00005" to .000075" runout"... Man...that is 5 hundred thousandths to 75 millionths of an inch. That is verrrrrry small. Another touts his method of threading on centers and cutting the center with a pilotted 60 deg cone with a pilot of the correct size for the bore. All well and good, but with those tolerances priviously mentioned, how does he get concentricity to match those with a "piloted" cutter? How does he chamber? He uses the tailstock to run the reamer in with the barrel running in the steady rest. How does he know the tailstock is in alignment with the headstock axis? Is he higher? Lower/ Left/right?. Does the reamer point right down the bore even if the barrel has a slight bend to it? How does he know if there is in fact a bend in it? Does the barrel have any runout say, 4-5 inches back from the chamber end? How about the steady rest. How does he set up the fingers on the steady to make sure the surface he runs on is in the same axis as the lathe center line? Is there any "slop" in the fit of the barrel to steady? .00005" tolerance? Even the best made barrels by the best makers are only accurate bore-wise to within .0002" by their own admission.

I don't have a problem with the methods used, only questions. I try to chamber my barrels using one or all of the methods touted, but after quite a number years of machining experience, I have, and am entitled to, a few reserves.

Let me know what you think, please. Was it a typo? Was it a bit of embellishment on the part of the writer

IMO the average guy doesn't know the difference between .7, .07, .007, and .0007. They may know the more zeros the better it is. So the smiths take license to "impress" the sport. I don't mean they exactly lie; they just tell the customer what he wants to hear. Kinda like a guide telling his sport that the 75 yard shot he made was 300.

It would indeed be pretty hard for a customer to prove or disprove any of these gunsmith claims. If the rifle shoots well and functions reliably, that's generally all that most customers need or want to know. Those tiny, incremental numbers add sizzle to the sales pitch, however, and that may be their greatest practical function.

I think the guys who are after the most precise target or varmint rifle possible, or the dedicated experimentor after self-gratifying paper statistics may be more interested and impressed with these ultra-precise runout numbers than I am.

Since my real interest is hunting rifles to be used for animals that are slightly larger than the garden-variety pocket gopher, I take some of this stuff with a grain of salt. In fact, in my experience, some of the ultra-tight chambering dimensions (tight necks, "deep throats", et al) severly hinder ammunition options, and can be a detriment to functional reliability. I'll take a superbly reliable rifle that feeds perfectly every time, yet can do no better than one-inch groups any day of the week.

AD

At the risk of being flamed, you can cut chambers with .0001 of TIR and do it regularly. Part of the time this won't prove to be the case and a chamber will wind up with 2-3 tenths of TIR, still a good chamber. The guys mentioned in the article are all honorable and talented men.
Perhaps their ability is beyond what we see everyday. However, talking about chamber runouts SMALLER than .0001 and doing it regularly is beyond me... As you said, there are many varibles, some of which the smith has no control over, that come into play..

Jim, for your information, Echols chambers his rifles right in the middle of SAAMI specs, and he pays particular attention to throat and lead dimensions. They function properly and shoot well with a full range of factory loads and require no tricky handloading proceedures. The exception being those rifles in .300 WBY. which are chambered without the Weatherby free-bore. These require special handloads. If a customer wants to shoot Weatherby factory ammo, the Weatherby-spec freebore is part of the package.

In contrast, I've had rifles build by a couple of these "benchrest" whiz-bangs that would not chamber factory ammo because of overly-tight chamber or neck dimensions, and I had one built in .30-06 with not only a tight neck but a short throat that was so short it would pull bullets out of factory loads. This guy succeeded in turning a standard factory chambering, in effect, into a wildcat, and I guess in the name of Blessed Accuracy.

In my experience, if you're building a hunting rifle with a standard sporter weight barrel, you'll never see a practical accuracy advantage with unusually tight chambering dimensions. There are times when the fettish for extreme accuracy goes too far with certain gunsmiths, and that was the point I was originally trying to make.

AD

Whoa, put the safety back on, Allen! I was just teasin' you a bit. Notice the smiley face at the end of the post.

Besides, knowing what goes into a Legend, if I was serious I would have offered at least a hundred dollars as boot!

(TIC, okay? )

They're full of crap! We do alot of work with our machine shops for aircraft gas turbines and to get tolerances to 0.00005" we are measuring with lasers. Show me any gunsmith with a laser measurement table directly fed into his $1,000,000 CNC lathe and I'll believe it. Until I see that type of machinery set up in their shop I'm calling "Bullshit"

Most of the banter in the magazine in question is about chambering for the 6ppc in benchrest rifles. And it has nothing to do with hunting rifles. When considering hunting rifles I agree with you 100%. When I'm looking for a benchrest rifle that I expect to shoot under .2" five shot groups, CONSISTENTLY, I want the chamber tolerances to be the best they can be.
Pat Byrne

Fjold,
I'm sorry but that video attachment under your name is just tOO distracting! In fact, it's starting to make a magnum lover out of me!
John

I believe in real world conditions, the type of metals we work with at the temperature fluctuations in a normal shop, the metal will expand and contract more than these guys claim to hold. I don't believe there is an engine lathe made that has a movable tailstock that can hold such tolerances in a reaming operation.
But then again, what do I know.....:-)

Maybe the writer wrote 5 ten thousandths, and the editor being an english major and avoiding math at all costs, thought... hmmmm ten thousand is 10,000 so maybe 5 ten thousandths is .00005! Thats what I think anyway.

Rancher, agreed! But "best they can be" is a loooong way from .00000etc, etc. I don't think it helps their credability. Do you?

Thanks for the headlights man.

Mr. Kobe, The article in PS was written by me. The precision of Mr. Clay Spencer's chamber run-out is written as stated to me. Just because you can't achieve this does not mean that it cannot be done. I don't really know if this precision is possible or not, but I tend to trust Clay's word for it. He is a perfectionist by nature and he will obtain the necessary equipment to do the job at hand. For you to impune the motives of those you haven't met and do not know speaks of your own character. This is my $.02 worth. James Mock

I'll buy .0001 accuracy.. anything past that, in a gunsmith's shop, is exaggeration? .. if it doesn't show up on a .0001 gauge, it's got to be zero, right? (not)

jeffe

i'd just like to know how a person would keep barrel and tooling at a equal and constent temp. while machineing, as well as have barrel steel and reamer steel that would expand at the same rate as they heat up while machineing. so a person could hold that kind of tolerances IF the barrel was stright enough, the reamer ground true enough and the machine was accurate enough for a person to chamber a barrel to less than "zero"!
just what kind of finish does a chamber have to have to be able to measure run out getting into microns?

Besides, setting up to a millionths (that is .000001) and trying to get me to believe that is foolhardy. Even D'arcy Echols would agree to that, I think. I don't think the author even knows how small that is.

I'm posting this information for D'Arcy Echols (I work part-time for him). D'Arcy has just spent a day with Clay Spencer in his shop barreling some of his actions with Clay. D'Arcy saw this thread but wasn't in a position where he could reply so on the phone last night he asked me to post this. In D'Arcy's words he guaruntees that what was written in the PS article is true and he has seen it for himself. D'Arcy will be home later this week and maybe he can give you guys some more details.

Now I don't know Clay or the author of the article, but I know D'Arcy fairly well and when he is willing to state something with that much conviction, I'm going to believe it.

To the nay sayers. Benchrest competitors routinely turn brass to +/- 0.0001 and to say that a gunsmith with 100's of thousands of dollars worth of equipment and measuring equipment can't control runout to 1/2 a ten-thousandth to 3/4 of .0001 is misguided. Some above doubted that we English majors do not know the difference in .7, .07, .007, etc. I don't know about Dave Brennan (editor), but I know for certain that I am not an English major (doesn't it show in my writings?). I can assure you that I know the difference in 0.0001 and 0.00001. Good shooting to all. James

Whoa, put the safety back on. I did not mean to impune anyone nor did I even mention any names. Mr Clay SPencer is "D'Rigeur" (SP) as far as I am concerned, he has way more talent and expertise than I could gain in a lifetime. I have nothing but respect for him. I have questions about the tolerances stated. I hope these guys understand that I do not question their abilities.

Careful James, don't get your ass up around your shoulders. Also, it seems your short term memory is getting faulty. I said: "the average guy didn't know the difference between .7, .07, etc". Another poster said english majors and math don't mix. In your post, you said "we english majors" then you said your were not an english major. Exactly what are you? Your obstreperous post because someone choose to doubt your article added only heat and no light to the subject. How many smiths do you know that have 100s of thousands of dollars of equipment in their shop??
One would think that you'd be pleased that someone read your article and found it interesting enough to challenge.

I would have to say that this either a gross exaggeration, or a misprint.
I have machined parts to tolerances of +/-.000075, and I can assure you that this something that is not done on manual equipment on your best day. Furthermore, it's a process that would require the use of a precision hone due to the irregularities in surface finish that would be machined. The surface finish, assuming that it was at least a 32 would be too rough to even measure such a dimension. You would have to bring that down in the neighborhood of 4 lap finish. When this can be done with a chambering reamer, I want to see it.
Furthermore, even the most accurate CNC lathes have anywhere from .00005-.0001" runnout at the spindle, to say nothing of your reamer holder, floating or not. If it floats, it's floating within the barrel, who's tolerances won't see those numbers either. Then you have the tailstock tolerances, which can easily surpass that of the spindle, and this is on CNC equipment with climate controlled cutting conditions. But, as soon as you begin to warm up the machine during cutting, these factors all change, sometimes significantly.
Now to say that your going to pull this incredible feat off with manual equipment is more than a stretch by a long shot.

Last, but certainly not least, is the inspection of this miracle chamber. I hope that it's not being checked in the spindle of the lathe, because you sure as hell have to get a more accurate setup than that to determine whether you've actually accomplished your goal. Laser measurement, as posted by someone else previously, would be about the only conceivable method that I could think of even getting in the ballpark of these tolerances. Even then, every form of measurement is governed by the method of fixturing the item for inspection, much like the machining process. Without a fixture that is approximately TWICE as accurate as the finished part, you'll only be amusing yourself in the inspection department. So, that means that your fixturing method would have to be as accurate as .000005" for a finished part tolearance of .00001". I suppose this is where I'd have to drawn the line on the BS meter.

Bottom line, how much difference will .0001 runout in the chamber make on the target? And how would you measure that?
BS for sure.

I'm not a Benchrest" smith so my opinions and experiences will be different , but I couldn't help but comment on this one.
I think I'll have to agree with Mr Williams on this one. I would even venture to say that if you are measuring .0001 and let 10 different "benchrest" smiths take this measurement, you wont get all ten to agree even when using the same tool.
I'd like to see someone air guage a barrel with several different guages, then let several folks test the same barrel with the same guage. Might be interesting....
Charlie

I hope you are not referring to me, Jim Kobe, when you refer to "James" in your post.

Nah, I was referring to James Mock, the author.

"And they shot the messenger." Folks, I am the messenger in this case. When I referred to "We English majors", I was reporting what was stated about me....maybe I should have used quotation marks.
The tolerances listed in my article were as they were reported to me. If they are impossible to attain, then so be it. I reported them EXACTLY as they were told to me. The gunsmiths in question have their phone numbers listed at the end of the article; why don't some of you non-believers give them a call and challenge their stated tolerences? Good shooting..... James

Think of it as a growth opportunity: Always check your sources and verify your facts.

Mr. Mock, I stand with the majority here. I'm also a toolmaker with over 25 years experience, with some time doing precision grinding (splitting tenths/.0001"). It ain't gonna happen! In his mind he may be holding those tolerances, in the real world it's not possible. If you haven't learned by now, any gunsmith is the best in the world, an only he can produce rifles to exacting tolerances. Sure would like to see his test equipment.

Beeman.... "Check your facts and sources" ???? The article was about the sources. The "facts" were the exact words of the sources. Also, many have reduced the runout in question (.00005 to .000075) to .000001 ....this is a long way from the original 1/2 a ten thousandth. Why did Spencer invest money in instruments that measure to 10 millionths place if he had no use for them??

I want to learn here... So please bear with me..

I chamber in the headstock. Some will argue that chambering should be done in a steadyrest, I've heard the debates.

I indicate a barrel in to as close as I can get it, my test indicator will be reading a .0001 or less when I get through setting a barrel up.. Then I turn the tennon, thread, and chamber. When done I always stick an indicator in the back of the chamber, up near the shoulder, and in the neck. This is in the ppc which has a case length of 1.5". More often than not I will be getting no more than .0001 or so of indicated runout. Ocassionally one will go .0002-.0003 but not very often. I have a rather nice assortment of indicators, and they all tell me the same thing. I realize the barrel is NOT in some kind of test fixture but WHAT IS THIS TELLING ME IF NOT THE RUNOUT OF THE CHAMBER ???????? No, I am not a machinist by trade.

Rancher, reread triggerguard's first reply. First off, the bearings in your lathe could have more than .0002 run-out in them. Even going from a cold spindle to one at operating temprature, with well oiled bearings will make a difference. Next, your indicators. If the indicator isn't made for a point thats 1.5" long, the reading is off. The angle of the point to the body is critical, can throw readings off. Cheap indicators have enough backlash in the gearing and give unreliable readings. It may look good while in the spindle, but a fixture to test runout is needed. When we start looking at .0001 measurements, its time for lasers or electronic measuring devises.



Sometimes you gotto look at what your doing and realize if theres a benifit to the tolerances your trying to hold, if its realy that critical for the application. Looks good to the uneducated, might end up being a waste of money and time. Yea, I can square up an action face to .0001, is it realy needed?

The spindle bearing may be out 2 tenths, now what? Less than .0001" RO "indicated" is the best you can do then, right? Even though it may be .0002" off, and you'd never know it?? Using a fixture would tell you you had a problem, and how much of one, if you had the barrel dialed in on the lathe, correct? Does everyone use a fixture to check his work? How one is fixtured to check this is eluding me.

Does anyone make a high quality .0001" indicator that will reach 4", or more, and is calibrated at 4", or more?

you know when i set a barrel up i set it up within 1-tenth of one thousands. if you go to my home web pages you will see the holder that i use to do this with. www.parrysgunsmithing.com

Brent, as far as the indicator goes, my short answer would be no. I'd have to do some research to qualify that though. I use Interrapid indicators, the longest point I have is 2 3/4" long. Using this point on my tenths indicator canges .0001" readings to almost .001". Seems like a lot of smiths use rods. Problem being, unless the rod is press fit, you have a built in error. Rod -.0002" for a slip fit, rod can be off .0001" from true center when you indicate it in.

Bottom line is don't sweat the small stuff. Smiths have been using their methods for years and it works. It's the idea that someone whom is claiming to do something that an experienced person knows is not practicle, kinda hard not to call em on their BS.

While in Virginia last week I spent a day with Clay Spencer in his shop watching him install a Krieger 30 caliber barrel on one of my Mod-70 actions. This was not the first nor will it be my last time I visit his shop. I watched Clay use his new, Spencer modified, Romi M-17 cnc lathe to thread and cut my 300 mag chamber so that the chamber run out measured at the middle of the neck, behind the shoulder, ahead of the belt and on the belt so the indicator movement read .00000. To measure this we used a Girod digital indicator with a 3" stem that was sent back to Switzerland and modified to read to this call out spec. The cost for the Girod re-vamp was $500.00. Some have said you couldn't make a valid measurement to varify these numbers, He's has the inspection equipment to prove it, it ain't guess work, it's real. We used a hydraulically dampened indicator holder to make these indicator adjustments. We then removed the barrel from the 6 jaw and then returned it to chuck within .00005. Clay threaded the barrel, fit and chambered it in less than 1 1/2 hours. I have no doubt he could have done it in less time without my constant stream of questions.Will this degree of precision make the rifle more accurate? is it nessessary for a hunting rifle or any rifle? is Clay saying he can do it better than anyone else? is it all smoke and mirrors? All good questions. You need to understand the mind that drives the desire in this guys work, He is not interested in anything other than extreme precision. What you and I think is of little regard in his personal goals. I'm sure Clay is trying to build a number of barrels and rifles that will shoot groups that measures ZERO, not once but again and again and again. What this guy has spent on tooling, fixtures, machines and time to realize this goal is an education in determination that I'm afraid only a few people will appreciate.Is is worth it to the rest of us?

Let me ask you, if you could send your action and barrel to Clay and have him do the same degree of work on your barrel and action for a total cost of under $300.00 would you consider it a waste of time and money?

Still in doubt? make the call, get on a plane and see for yourself. Until then then you're pissing down both legs with speculation and criticism

D'arcy:

I have stated earlier and I will repeat: I think the world of this man and the other gents in the article and of thier talents. I would dream to be of their caliber. I do not try to riducule them. I have a problem with the gent, and his editor, who tried to BS the public by adding a few decimal points in his article.