I would like to know the preferred method used by the people that frequent this board on chambering. Do you chamber in the head or on a steady? Why?
Jim

This has been covered a million times on as many sites. The bottom line is that any system that results in the barrel running as straught and true as possible gives good results providing it is at the same time perfectly aligned with the tailstock. There are times when it is advisable to chamber in the headstock such as with a very light barrel. The skinny barrel lacks torsional rigidity which can promote chatter so it may work better to chamber this in theheadstock.
Mostly I prefer to chamber in the steady and I prefer to cut my threads between centers. Any time I have seen oversized chambers cut it was when the smith was chambering in the headstock. Now, if he had been more thorough in his setup it wouldn't have happened but if he had trued the shank and run it in the steady it wouldn't either and it would have been faster.
Believe it or not I have watched a well regarded gunsmith simply chuck the barrel in a 3 jaw chuck with about 1 1/2 inches protruding and thread and chamber it this way. This was his standard procedure! That some chambers were oversize or misaligned he blamed on the reamer.
Also I have yet to see a floating reamer holder that would truly float axially when under load so there are limits to what can be expected there as well. One fellow told me of a German holder that floated perfectly in all directions and cost on the order of 1200.00. I figured for 1200.00 I should just have to show it the barrel and it would do the rest!
Do what you are comfortable with and if you do it properly your chambers will be on size and in perfect alignment. Use any technique incorrectly and a good job will be a matter of chance. Regards, Bill.

Talk to any journeyman machinist and he'll tell you that if you want to hold the tightest possible tolerances, whether it be with the threads, the bore, or the OD, you position the workpiece as close as you can to the face of the jaws. If you used a steady rest to thread and bore any other item other than a rifle barrel in a real machine shop, they'd run you out on a rail. The rule of thumb is, don't let the workpiece extend past 5 times the diameter of the workpiece. In otherwords, if you're barstock is 1" in diameter, don't let it extend over 5" from the chuck. This is the most extreme situation. The closer the better.

Ditto what Bill says. Alignment & rigidity are the key factors. 1000th post!

Bill got it right----

The steady rest method halves the error of the out-of-straight barrel. (all are crooked)

I chamber barrels just like the lathe headstock and mill spindle was made......steadyrest. It's been done that way for many years.

Barrels *can* be chambered in the headstock VERY accurately, but no better than by steady rest and set up time is MUCH longer to get right.

Why would you use a device (steady rest) to stablize a barrel that is unstable because it has been pulled away from it's primary clamping area? I realize that this is the "standard" for which it is normally done by the gunsmithing trade, but in the world of precision machining it's crazy. What needs to be accurate is the concentricity of the bore to the O.D. and the threads, along with the squareness of the shoulder. Of course the reamer must run concentric with all of the above mentioned items as well. When you take the barrel and extend it out away from the chuck, what happens? It becomes unsupported. So, you make up for this by adding a steady rest and tailstock. Why make up for something you can avoid in the first place. Not to mention, you will greatly increase your setup time as well increasing your chance of error in respect to holding true position to the bore. I'm curious, how long does it take for some of you guys to setup and chamber and cut threads on a barrel? We normally pull it off in about 45min on the average, but when we have quite a few to do and don't have to tear down and setup on tools, we can sometimes get them done around 35min.

Some how guys, I think this little bit of humor I got the other day kinda fits for this topic.

Start with a cage containing five monkeys. In the cage, hang a
banana on a string and put a set of stairs under it. Before long, a
monkey will go to the stairs and start to climb towards the banana. As
soon as he touches the stairs, spray all of the monkeys with cold water.

After a while, another monkey makes an attempt with the same result.
Again, all the monkeys are sprayed with cold water.

Pretty soon, when any monkey tries to climb the stairs, the other
monkeys will try to prevent it. Now, stop the cold water treatment.

Remove one monkey from the cage and replace it with a new one. The
new monkey sees the banana and wants to climb the
stairs. To his horror, all of the other monkeys attack him. After
another attempt and attack, he knows that if he tries to climb the
stairs, he will be assaulted.

Next, remove another of the original five monkeys and replace it
with a new one. The newcomer goes to the stairs and is attacked. The
previous newcomer takes part in the punishment with enthusiasm.

Again, replace a third original monkey with a new one. The new one
makes it to the stairs and is attacked as well.

Two of the four monkeys that beat him have no idea why they were not
permitted to climb the stairs, or why they are participating in the
beating of the newest monkey. They enjoy doing it anyway.

After replacing the fourth and fifth original monkeys, all the
monkeys that have ever been sprayed with cold water have been replaced.

Nevertheless, no monkey ever again approaches the stairs. And why
not?

Because that's the way it's always been around here.

... And that's how policy begins

For years I had a lathe with a small hole through the spindle so I did all my barrel work between centers. And I turned out some very accurate barrel jobs if I do say so myself.

Then I aquired a 5900 Clausing with a large hole through the spindle and began threading and chambering barrels through the spindle. I have a 4 screw spider on the back side and indicate both ends to .0001". Due to more rigidity I get a much smoother finish in the chamber and on the shank and threads. I now use this method when possible.

I can think of some problems to avoid using either method. If chambering between centers I strongly recomend you buy a set of piloted center drills to get a very accurate 60 degree center cut. If doing barrel work through the spindle you must very careful not to introduce axial stress on the barrel with the 4 jaw chuck. This normally happens when you adjust the 4 jaw chuck first with the jaws very tight then adjust the muzzle end at the rear of the spindle next and you actually put a bow in the barrel.

I know there are some very good accuracy gunsmiths who build winning competition rifles using both methods. I think either method is good, it is simply a matter of which one you get the best results and are most confident with. There are a lot of good machinist who turn out flawless work with differant approaches. They both have one thing in common, they persue excellance at any cost.

There is one thing about using a steady rest that really irritates me. You will read an article about some one building a varmit rifle or target rifle and there will be a picture of the barrel in the steady rest and being driven by a 3 JAW CHUCK! It should be done between centers or if you must drive the barrel with a chuck it should be a 4 jaw chuck and then only after turning the outside of the barrel concentric with the bore.

Thank you all for sharing your experience. The reason I ask is that a barrel maker I respect very much told me that the only way to accurately chamber a barrel is on the steady and I don't agree. It seems to me that just like triggerguard said " if you want to hold the closet possible tolerances you position the work as close as possible to the chuck" It just flat makes sense to me. Thank you all again. Jim

Guys,

Can I ask what the prefered method of holding the reamer is? I'm aware of several methods but have heard the floating holder mentioned most often. If this is the prefered method then which brand of holder is recommended?

Can you tell I'm getting ready to try to cut my first chamber?

Thanks,

Mike

Mention a method around a bunch of gun plumbers and you get different answers from each gent. The answers depend on a lot of things: Who taught each plumber, what he has seen or read by others, what equipment he is using, equipment limitations, and, one that I really like, just how much formal or "real hands on" true machining experience the gent actually has. And we are all biased depending on our "perfect" method. One of the ways a good machinist (note I said machinist, not gunsmith) is judged on is how well he can handle setup conditions in a variety of machines when faced with unusual or difficult to handle items.

I chamber through the headstock and also with a steady, depends on the situation at hand. My chambering lathe (I have three lathes) has a 1-1/2" spindle bore and can't take less than a 26 inch barrel through the headstock. So, the shorter barrels get the steady.

My steady is much different that the conventional three finger steady, it has a hollow rotating spindle that works just like a 4 jaw chuck, so I do not have to turn a true area on the barrel for steady fingers to rub on. And it will take octagon barrels or let me crown or thread a muzzle that has a sight ramp. Try that with a three finger steady, you get into the time consuming and error producing world of catheads in a steady.

The key in accurate chambering, makes no difference if you go through the spindle or use a steady, is accurately setting up the barrel true to the bore centeline. And, as Jack mentions, ain't no straight barrels out there, does not make any diference how much you pay for them!!! Another interesting thing: I have pilots in 0.0002" increments in all bore sizes for my reamers, I select a snug pilot to fit the bore (bore sizes vary a lot too!). I have long rods made up so I can attach a pilot to the end of a rod and push the pilot bushing completely through a clean and lightly lubricated bore. You will get some real suprises on snug and loose areas in a barrel along the bore, even those expensive ones! I have a standard chambering checklist with drawings that I use when chambering a barrel, it also has spaces for me to enter the total dial indicator runout (TIR to you machinists) of the outside diameter of the muzzle and breech with respect to the bore centerline. You will see some suprises here also, even in expensive barrels, especially the TIR difference at the muzzle end of say a 28 inch blank and at the finished muzzle length.

How to hold the reamer, muzzle flush pumped coolant systems, lathe speed, reamer feed rate, chip removal, how far to run in the reamer before pulling out for chip removal, etc., are all very important and will take several pages of text and photos to describe properly. If a gent is getting into chambering, the best advice is to seek out an experienced hand and observe, then read of other methods, practice with your own equipment, and formulate your own methods. Never stop asking questions and learning, I learn new techniques every week. One method I stumbled on a few weeks ago made a significant change in my method of chambering, it was one of those moments when one says "Duh, why did I not think of this years ago!!"

One last comment: I chamber upwards to 5 or 6 barrels a week. I built a muzzle flush pumped coolant system about 5 years ago. If you are not using this type of system, you are wasting your time. Not only can you chamber much faster, but the finished chamber is much smoother, chips are continually flushed out, and the reamers run cool and do not suffer from heat build up. I chambered a 6.5x284 barrel today, running the spindle at 300 rpm, took less than 10 minutes from the time I put the reamer in the holder until I was at the final headspace, including several stops along the way to clean out the chamber and put the gauge in to check. A pumped system changes your whole philosophy about chambering!!!

[ 09-14-2002, 11:51: Message edited by: John Ricks ]

Note Craftsman's comment about three jaw chucks, take it and file it in a good place in your memory if you are beginning in the world of threading and chambering barrels!!!

I had a rifle in the shop recently that was assembled by a well known and well advertised gun builder ( and expensive!!!). The rifle is a hunting rifle in a big 30 caliber. This rifle had a lot of expensive truing and re-machining accomplished by said gun builder. It was shooting 1-1/2 to 2 inch groups at 100 yards. After I took the recently installed new barrel off and took measurements, I found the chamber was 0.004" out of being concentric with the bore, the chamber was 0.006" larger at the chamber mouth than SAAMI standard and the receiver "truing" was accomplished incorrectly. I installed another new barrel, chambered it correctly and corrected the receiver machining errors. I shot a three shot group with this rifle that was less than 1/4 inch at 100 yards after I corrected all the problems. It looks like the previous gun builder used three jaw chucks extensively and his tolerances stacked up. Maybe even used a drill chuck to hold the reamer, who knows. Like Jack says on another forum, quality is not determined by how much money one spends.

HEY'
This is a grat topic for a layman,like me.I learned a lot reading your replies.It seems to me,that not all gunsmiths,regardless of their reputations,use the proper methods,in chambering.I don't know the method that my gunsmith,uses for chambering.I have been using him for many years,and all the rifles that he built,or replaced barrels,shoot a 1/2 " or better.Am I to assume that he is doing the right thing?Or am I just lucky?By the way I don't think,his reputation goes beyond the town his shop is in.
1geejay
www.shooting-hunting.com

I have to agree with Bill. I do all my work between center's with a steady rest. I use Shilen select match stainless barrel's unless someone want's something different. I use all removeable pilot,reamer's,center drill's and crowning tool's. I have pilot's in .0001 increment's. I have found the Shilen barrel's to be very uniform.
Since 98% of my business is target rifle's, if they don't shoot you don't get any return business.Your name came go up or down very fast at a match even if it's one of those people who blame's every one but himself for his failure's. I had a guy tell me his rifle wouldnt shoot. I had the guy who won the IBS score shooter of the year for 2000 & 2001 the 2000 national's and part of the 2001 national's shooting one of my rifle's shoot the rifle. He shoot 23 straight x's. The guy then said the rifle would only shoot for Jim and he thought the bolt was bent.
I once bought 7 A&B barrel's for some sporter project's on a friend's recomendation. Two of them were nice and uniform. The rest a bushing would start in nice them fall out the other end or start in nice go loose then fetch up. I know some people like them and seem to have good luck but they are not my cup of tea. I think you get what you pay for.....
I agree with John Rick's about the muzzle flush. I have been using one for 6 year's and would never go back. The chamber's come out so polished I go back and rough them up a little with 400 to keep the bolt thrust down.
Something every one who posted I am sure know's but those who don't do much machining may not is tailstock alignment.It must be right and checked often.

This is a highly informative thread! I am surprised by the negative comments about 3 jaw chucks. I have always been told that that these are second only to collets for concentric accuracy. Could some of you learned experts explain what is wrong with the 3 jaw chuck?

Thanks,
Axel

I just went through some of these threads and I just admit I did not completely read all of them. I chamber using the steady rest method. Someone early on said "all of them (barrels) are bent". To a degree, he is correct. If one sets a barrel up correctly, It should run concentric and axially correct with the axis of the lathe. By indicating in the chamber end and the muzzle end, are you accomplishing anything? What about the middle of the barrel. In other words, what I am saying is the reamer should enter the bore of the barrel concentrically and axially true within a tenth or two of the bore. How would one do this. I use a gauge pin in the bore and indicate it in when it sticks out of the bore the same length as the chamber. The outside, the threads, is now running concentric and true with the bore and the chamber can be cut accordingly. I further set it up to run in the steady by single pointing a 60 deg center in the chamber end and cut the outside area for the steady thus. Confusing? That is why there are so many different methods. I know an accuracy gunsmith who sets his Jacobs chuck in his Aloris tool holder and cuts his chambers that way. I often wondered how he got everything lined up correctly.

Regards, JIM

Again, "Different Strokes for Different Folks".

RE the crooked barrels, you just gotta understand what is going on and master your technique to make the most of a barrel chambering job. Let the reamer follow the bore axis, you want the chamber axis to be right on with the bore axis. Threads also, they should be concentric with the bore axis. There is a way to do both, this is a topic for future discussion.

The key is to master your technique and equipment to produce quality results. Some of the techniques we use, especially for precision target rifles, are closely guarded secrets. And there is a whole world of information and techniques about chamber reamers for precision rifles, the reamers are different than a SAAMI or CIP reamer. Things like throat lead, throat angle, tight necks, tight bases, that are required in a match rifle chamber but will not work in a hunting rifle.

I am entering into a project to inventory all my machinery and equipment for insurance purposes. Along the same path, as I am a one man shop with no apprentice or dependents to "carry on", is a project to document what the special tooling is for and the methods of use. Reason for this is some poor fool, when I check out of this game, at hopefully many years off, will have to sort out all the stuff I have accumulated over the past 35 years and figure out what to do with it. Would be nice to have the whole package go to an individual starting out in gun work instead of letting the auction vultures split it up. In addition, I am hoping to publish the information in book form in order to help out many others.

Although my favorite rifles are classic big bores, I dabble in long range benchrest, tactical, and 1000 yard rifles. You gota be very careful in the setup and machining of a rifle of this nature, and check & recheck the setup often. I work to 0.0002" or less TIR when building a precision rifle, it pays off in the end. A few rifles on the back log include three for 1000 yard work: A 338 Improved Lapua, and two 408 Cheyenes. The Lapua goes on a Nesika action single shot action, the Cheyenes go on Prairie Gun Works custom single shot actions.

Isn't this game fun, there is always something new to learn, at 55 years of age I see new stuff every day!

Axel,
If you can put a three jaw on a given piece of equipment, true it up so that it is perfectly concentric and never remove it from that piece of equipment, a three jaw is as good as any. I don't have the luxury of multiple lathes so I must frequently change chucks and if I ground the jaws every time they wouldn't live very long. I don't have a tool post grinder to begin with. They are somewhat pricey and one won't fit into my tooling budget just yet. I know it can done using other methods but the jaws still end up being sacrificed. Jim

[ 09-14-2002, 18:53: Message edited by: Lightnin ]

John Ricks,
I went to your web site and I am impressed to say the least. It caused me to slobber and salivate all over my keyboard thereby causing a short and frying it. Where do I send the bill? Jim

Lightnin, there is a lot more to the shop than you see in the web site photos. Remember, its a many year collection of equipment. Over the years I preferred to invest my money in machinery and tools instead of boats, cars, etc. Had a period of time when the Military and Women got in the way, but that is over now. Funny thing about Women, they spend money on me now!!!

In a more serious tone, gun building is like any other sport. You just gotta decide which endevor is for you, then strive to learn as much as possible, the learning quest is never ending. I would love to have some young individual that seriously wanted to learn this game and be sort of an apprentice, but sadly the youth of today are not interested in learning good hands-on skills and our society has taught them that all guns are evil and politically incorrect.

Gotta go, the shop is calling!

So the problem with the 3 jaw chuck is that of spindle thread pitch line runout? Would this problem also exist with collet chucking?

Axel

Most three jaw chucks can't be trusted for precision past about plus or minus .0015. Sometimes you get lucky like I did and get one to run true within about .0005 consistently. The one I recently acquired has proven to be exceptional on all acounts, and to think it's made by Jet. A pleasant surprise indeed.
When it comes to collet closure systems, I use them a lot. The problem that they have is the same problem that 3jaw chucks have, inconsistency. They're fine if you intend on machining and qualifying the entire workpiece, but they cannot run close enough for tight tolerance work. One other problem that you will run into with a 5c collet is that you can only push a 1" diameter piece of barstock completely through them.
John Ricks, I have to agree that you never stop learning. The amount of knowledge that must be obtained to be an accomplished machinist far surpasses that of any doctor in the medical field today. Some would argue this, but when you ad up the amount of knowledge that you carry to your machine everyday regarding speed & feeds, tool deflection, tool grinding, rake angles, etc., there's a lot. That's before you even get started into programming CNC's with different controllers. A good friend and former employee of mine once told me, "The day that you stop learning anything, get out. Pack up your toolbox and find something else to do for a living, cause this aint for you." He was exactly right too. When you quit learning is when you quit being a machinist. I've programmed probably over 3000 jobs on CNC machines over the last 15 years and I've yet to come to work when there wasn't something that I could say that I learned. I intend on keeping that way.

The problem with the three jaw is not whether or not anything will run true. If you chuck up a barrel in the three jaw and then work on the other end, you can't be certain that the outside of the barrel is running true with the bore. They most cetainly do not and you end up with an alignment problem. The same can be true with turning and threading between centers. Even if your centers are concentric with the bore, the middle of the barrel won't necessarily be true. I wonder how any barrel maker can tell me whether or not the axis of a barrel is straight all the way through?

Jim

Triggergard,

I find your statements very interesting. Are you aware that collet systems are used, almost without exception, for hard turning bearing journals. The concentricity tolerance on these is measured in fractions of a micron with TIR of less than 2 microns. That seems pretty accurate to me. Conversely deep boring accuracies are much less. As many on this thread have stated already, good luck finding a barrel which has a tight projected true position of the bore.

As an experiment I indicated in the three jaw chuck on two lathes. One is my own and the other is the greatly abused Mr. Fix-it lathe at work. My lathe's 3 jaw chuck had a TIR of < 0.0002" while the lathe at work had a TIR of < 0.0006". It is very difficult to get a 4 jaw chuck to actually attain and hold that level of concentric accuracy in my experience. I too have programmed CNC machines. So I know what you mean by learning something new everyday. Although I fail to see the connection between programming and machine tooling inherit accuracy.

Are these 3 jaw chucks that do not hold TIR well made in China and Taiwan? I have never had problems with German chucks. American made chucks are good too, although not as good as German.

I do appreciate the feedback. I find it interesting to hear to other opinions and experiences.

Axel

You missed my point. The inaccuracy of the three jaw setup lies with the barrel itself. If you chamber and thread using the three jaw with the barrel held thusly (SP), how can you be sure the bore is running concentric with the portion of the outside of the barrel held by the chuck? if in fact it is running true, are you sure the middle of the barrel is also running true?

Jim

Jim,

My posts were not entirely addressed to you. Your comments are completely irrelevant to the accuracy of a 3 jaw chuck as you have stated. You are in fact commenting upon the concentricity quality of the barrel being worked on.

In your example you would need to turn between centers. This obviously poses a significant problem since one of those centers needs to be a chamber reamer. The real issue with your posts is barrel quality. If the bore is not held to a tight projected concentricity tolerance you will have the bowed bore you are explaining. This is easily gaged with a gaging rod ground to the minimum allowable diameter specified by the projected concentricity dimension I believe.

Axel

Concentricity of the barrel OD with respect to the bore axis, or centerline, is irrevelant if one uses the proper method of centering the barrel in the lathe: 4 jaw chuck and a 4 screw cathead on the outboard end of the spindle, or a 4 jaw chuck with a trued muzzle area and a 4 screw or 4 jaw steady as I described earlier. Over the past 5 years or so I have recorded TIR of the breech and the muzzle OD with respect to the bore centeline. In my spare time (Hah!) I should go back and compare this data to target groups to see if it tells me something.

The method is to try to obtain as near zero runout of the bore at the muzzle end of the barrel, and the bore at the breech end of the barrel, with respect to the centerline of the lathe. (You may never get eveything perfect due to the machining inaccuracies and "lack of straightness" of the barrel.) One may accomplish this by use of precision machined bore plugs inserted in each end of the barrel for an indicator stem to ride on, or by use of a long stem indicator that is inserted into the barrel bore. The long stem indicator is a preferred method for many benchrest rifle builders, they strive to have the indicator point at the area in the bore where the throat will be after reaming the chamber. Chamber is reamed first, then another dial indicator check is made, this time with the indicator stem at different points in the chamber and throat, and a best average is taken, then the barrel is recentered and the threads are cut concentric to the reamed chamber. This method is generally only used if the action has a good snug fit of the bolt and the receiver threads have been recut so the receiver threads and the bolt centerline are one and the same. (Meaning one of the custom single shot benchrest actions or a heavily tricked up M700 Remington)

The long stem indicator method reveals many things to a careful eye: How deep each groove is, if we have inconsistencies in land heights, width of grooves, etc.

I use both methods, depends on the rifle type being built. My long stem indicator reads to 0.0001" and a guy can spend a lot of time getting the barrel in the "perfect" chambering position, whatever that is.

Like I said earlier, the method is different for each type of rifle and barrel. No point in putting all the "benchrest quality" time into a rifle that will be used for shooting wild hogs at 20 paces.

It is easy to "nit pick" and spend too much time on minute details in the chambering process, especially when the work is being done to improve cash flow for the shop!!!!! Like the old man said, "We ain't here to make guns, boy, we are here to make money!!"

[ 09-16-2002, 06:42: Message edited by: John Ricks ]

A couple of photos showing the "bore plug" method, using the 4 jaw chuck on the spindle and the 4 screw cathead on the outboard end of the spindle. "Bore Plugs" are about 3 inches long, machined from 7075T6, and have about 1/2 thou taper. I have a considerable collection of the things, as there is a wide variation in bore sizes among the different barrel makers and even in the barrels from a single maker. The big end of the plug is tapped (1/4-28 for 7mm and above, 10-32 for 6.5mm and below) so I can screw in a small slide hammer to withdraw the snug fitting plug out of the bore.





If you look closely at the photos you can see the protective copper bushings between the setscrews and the barrel. Likewise between the chuck jaws and the barrel.

In both photos I am just starting the dialing in process, the indicators read to 0.001". I "rough in" to 0.001" or so, then switch to 0.0001" indicators.

John- As always, you and I are in total agreement with respect to using the 4 -jaw chuck and outboard 4-screw spider method with a bore plug indicator system to obtain maximum accuracy in cenering the barrel in the Lathe. I hope that the folks on this site are paying close attention as you are providing some hard won knowledge free of charge and with pictures to boot!
I use the same method ( now also with a high pressure barrel flushing system for most of my work). I have also used the steady rest system for chambering with very good results. I have also seen the results of "expensive/reknowened gunsmiths " who use three jaw chucks for threading and drill presses for reaming(ever wonder Why all those factory TC Contender barrels don't shoot accurately)? I've also seen those hand reamed chambers ( you know those with big rings in them), Egg shaped- well that also doesn't matter does it? II's also interesting to me that people can be so arogant in their insistance that only they know what works without obviously ever having built a rifle in their lives.
Nice job on setting folks straight!. you've got more patience than I have.-Rob

[ 09-16-2002, 08:23: Message edited by: Robgunbuilder ]

John RIcks'

Thanks for the reply! You hit the nail right on the head. This is the type of stuff I was inquiring about. Apparently "Axel" got on the wrong thread when he referred to the three jaw. I think he thought we were espousing the virtues of the three jaw. If I get to that beautiful Olympic peninsula, I would love to stop in.

Jim

That set up sure looks familiar.
Same thing I use, copper protecting the barrel and all. Only difference is that in my spider I use brass screws so I dont have to use the copper on that end.
I also use the chamber flushing. I have one from Greg Tannel. It works good.

Tested my 3 jaw yesterday. I trued a piece of 1" drill rod between centers, then chucked it in my 3 jaw. I was pleasently surprized when it only hade .002" run out. Not that I will ever chamber with it though I was just curious.
BTW, I have a Wilton Lathe.

Thanks for the picts John

Celt

John Ricks,
Thanks a million for your detailed input. I like Rob am in complete agreement with your method. I'm certainly glad I started this thread. What a wealth of information I have gleaned from it. Thanx again to all who posted.
Jim

I've been gone shooting for the weekend and so have just returned to the thread and have to mention a couple of things.
First off, it is unlikely that a journeyman machinist would be run out on a rail for using a steady in doing precision machine work. I never was. In some cases the use of a steady is mandatory to accomplish work that is concentric and perfectly aligned. Especially when dealing with tubing which is likely to have a bore that is both eccentric when compared with the outside and misaligned. In a case like this the turning of a steady track which is concentric with the bore and another concentric track at the driven end for dialing purposes is SOP. Properly done it is possible to bore halfway through a piece, turn it around, and bore from the other end and have the bore meet precisely using a steady rest. It is also possible to thread inside and have those threads perfectly concentric with the bore and perfectly aligned. When you are working with pieces 12 feet long and 12" in diameter you don't do this without the use of a steady!
With rifle barrels it is a rare barrel indeed in which the bore is straight from one end to the other so that all attempts to ensure that the bore in the middle of the barrel is concentric with the outside are likely to be approximations at best. You can only be sure that the out side in the middle of the barrel is concentric with the bore at either end. If this is done, then the center portion of the barrel can be set to run true in a four or six jaw chuck but if so then only the outside will be sure of running true and only with the ends. The truth is though that this is adequate. The holding of the barrel in a three jaw chuck at the muzzle end or even in the middle while running the chamber end in the steady is also probably OK since runout of the bore is not likely to be all that bad and certainly not outside the capability of the reamer to follow the bore. This for chambering only, by the way, not for threading which should be done between centers.
I have seen highly regarded accuracy smiths set up a barrel in the four jaw chuck and dial in both ends. They are grabbing a paralell section in a four jaw chuck which may or may not have jaws which are aligned with the axis of the machine. They then dial in the muzzle end of the barrel and by doing so are actually bending the barrel so that the muzzle end will run concentrically with the axis of the machine. Those that are aware of this will hold the barrel in the chuck using narrow brass or aluminum strips which will, to a certain extent, allow the barrel to pivot. Some will use an extended guage system which will allow them to ensure that the chamber section of the barrel is running concentric and in perfect alignment with the axis of the machine and don't much care what the muzzle end does. In other words they are more concerned with the throat area of the barrel running true than any other portion. This is a necessity if one intends to bore the chamber for instance in the roughing operation.
It is certain that no system is always 100% perfect and there is a certain amount of compromise in each. It is just as certain that an intelligent and creative machinist/gunsmith is capable of getting the best out of each method. Likewise the inept can screw up using the best of set ups.
I have seen receivers which were "blueprinted" by smiths whose methodology was seriously flawed and as a consequence were probably no better than before and in some cases worse. Likewise custom actions which were supposed to be perfect were far from it whether from improper technique or improper employment of proper technique.
As I mentioned earlier, I've not seen a floating holder which reliably allowed a reamer to float axially. All, when under load, located the reamer in a center position. Now, this center postion was not always coaxial with the tapered shank and therefor the tailstock barrel. So, when using one of these it is necessary to load the holder then adjust the tailstock to ensure that the reamer was held center in relation to the barrel. In one system the holder itself was used to center the barrel which was trued and then run in the steady. This ensured that the two were concentric to each other at that point at least. Concentricity throughout the range of travel of the tailstock barrel was dependent on how well the axis of the tail stock was aligned with the machine axis and is so dependent regardless of how the barrel is held. Holding the reamer in a tap wrench and supporting it on the tailstock center is a perfectly good method by the and even better if a ball center is used in the tailstock.
As I said earlier, all methods have certain potential deficiencies. Successful use of any method comes from an understanding of these deficiencies and an ability to take an intelligent approach to minimize the effects of them.
The errors that may result from the use of a three jaw chuck are errors in the chuck itself or from improper mounting. Generally the chuch is as accurate as the scroll so that a three jaw may run perfectly when holding a 1 1/2" diameter piece and runout .002" when holding a 1 3/4" piece for instance. In addition, the jaws (as with a 4 jaw) may or may not be perfectly perpendicular to the face of the chuck. I have one four jaw wherein one pair of jaws are perfect while the other pair are decidedly misaligned so that a true test bar runs out by .010 12 inces out from the chuck but in one direction only. If a 3 jaw chuck has been mounted eccentricly on a plate then it will, of course, run eccentric unless you are lucky and the errors cancel out! Regards, Bill

Bill brings up a very good point when setting a barrel up in the spindle, using the 4 jaw chuck and the outboard spider. It is extremely easy to spring the barrel. Think of a crowbar: the short claw end is clamped in the heavy chuck, and the other end where you push with your hand is in the spider. It does not take much push with one of the spider screws to bend the barrel. The narrow soft copper bushings I use in the 4 jaw chuck allow the breech end of the barrel to move when the muzzle is dialed in. One must use a dial indicator on each end of the barrel and observe what is going on while dialing in. When adjusting the muzzle end you will see movement on the breech end dial indicator. If you do not see this movement, you are springing the barrel. Dialing in the barrel is is a back and forth method, adjust one end, see what is happening on the other end, and continue. And you gotta have two indicators set up.

I positively second Bill's comments about some of the "Accuracy" smiths. I had a rifle in the shop recently (a M70 hunting rifle, in 300 Win Mag), it was rebarreled and the action trued by a high priced gent. The rifle grouped at best 1-1/2 inches. I found many things wrong with the action and barrel chambering, but the one item I have a hard time understanding just how it was done was the finding that one bolt lug was 0.005" off. The fresh machining from the previous "smith" was evident. The bottom lug was taking the load, and being the weaker in the receiver, the receiver was springing until the top bolt lug impacted the receiver lug. Must have been a pretty bad barrel vibration that was set up. I corrected all the mistakes and the rifle now shoots 1/4" groups.

Hi all or ya'll, since I'm from the south. I'm new to this board but already know many fo you from other boards. I totally agree with John Ricks and all of his posts on chambering. I also put on 5-6 barrels a week. My preferred method is through the headstock, but occasionally chamber on a steady rest if circumstances require. I find it easier and quicker to setup a barrel through the headstock, but that is what I'm used to. Setup, threading, chambering, and crowning takes about one and ahalf hours, if the dang phone doesn't interrupt. I've never had a problem with springing a barrel, but that is something that I'm careful to avoid.