I am curious as to how a one piece barrell is installed, I see pictures of them and they are threaded, but how do you get the sight to be at 12 o' clock precisely and the barrel to be tight? How do you adjust the forcing cone to cylinder clearance without loosening or tightening the barrel? I know to the experts these may sound like really stupid questions but I honestly have no idea or I wouldn't be asking ya'll.

If you are VERY lucky, it will screw in and time correctly (with regard to front sigtht being at 12 o'clock), and be long enough at the barrel-cylinder gap that you can take a little material off the forcing cone to set the gap. Early Smith barrels before sometime in the 80's had a pin to hold them in place and prevent unscrewing. Newer ones are just torqued into the frame.
I've only replaced the pinned ones.
If you aren't lucky, then you have to turn a bit off of the shoulder to allow the barrel to screw into the frame more. (it isn't usually necessary to re-thread the little bit since it's normally less than a full thread). This is done to time the front sight, fit the gap, or both.
If more than that is taken off, then you will probably have to shorten the ejector rod and center pin to fit the relocated locking lug.
I'm no gunsmith, but I've successfully replaced a few barrels using simple tools. I've turned miniscule amounts off by chucking the barrel in my drill press and using a fine file. I've adjusted forcing cone length with a counterbore with brass tubing stock slid over the pilot to protect the rifling. I wouldn't do it myself for a high-end gun, but for a shooter, it worked just fine.
Chris Taylor

You don't move the barrel to adjust barrel/cylinder gap. The barrel is fixed and if the gap opens up, it is due to the cylinder moving back, and that is repaired at the end of the yoke. If you are putting on a new barrel, the shoulder is what determines where it will be when it tightens. The other poster described it pretty well. There is not normally an reason to remove the barrel.

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Louie the Lump
NRA Life

Maybe over-kill, but here's something I wrote on how a revolver barrel is fitted.
Much of this was to illustrate why you can't just screw a barrel on:

Changing a revolver barrel
A common question is “How do I change my revolvers barrel”?

Barrel work is a MAJOR pistolsmithing job and requires a considerable amount of very expensive equipment.
It involves a lot of steps that most people, including a surprising number of gunsmiths, don’t even know is required.
Failure to do the job correctly insures an inaccurate revolver at best, and a destroyed frame at worst.

The common do-it-yourself technique is to use “expedient” tooling techniques that are found in old gunsmithing books, and can still be found mentioned occasionally in gun magazines.
These methods range from wrapping rope around the barrel and using it with a stick to form a sort of tourniquet to unscrew the barrel, to the most common, which is to use a hammer handle through the frame window as a “wrench”.

The hammer handle method is to make up a pair of wood barrel blocks for the barrel.
The barrel is sandwiched between the blocks, and are locked in a shop vice. One writer said to “Tighten the vise until your eyes bugged out”.
A hammer handle or a shaped wooden 2x4 is shoved through the frame and is used as a “wrench” to twist the frame off.
The new barrel is fitted by hand filing the barrel shoulder until the front sight is at 12:00, the rear of the barrel is filed, if necessary, to provide a small gap between the barrel and the cylinder, and you’re off to the range to shoot your fresh re-barrel.

At least that’s how it’s touted as working.

In reality, when the hammer handle is used to turn the frame, one of two things happen:
Either the frame bends, or it breaks.
Revolver frames are a lot softer and easier to bend then most people suspect, and when the frame itself is used as a wrench, the frame will almost always bend.
Once bent, the frame is ruined even though it may still be shoot-able.
A bent frame will often have timing problems, and always has alignment problems. All of which cause inaccuracy and possible spitting of bullet metal.
Some owners who’ve tried this method of barrel work, are surprised that the factories do not have some kind of machine or device that will straighten the frame like bent car frames can sometimes be straightened.
The fact is, once bent the frame can never be repaired, and the best a factory can do is replace it.

The second thing that can happen is the frame will break.
If you look at a revolver frame just under the area where the barrel screws in, you’ll see that the frame is very thin in this area.
When the unsupported frame is unscrewed with the handle, it can crack right through the threaded portion.
While there are ways to weld the crack, the very high expense of having a top level custom pistolsmith/welder do it is very prohibitive, and is reserved for repairs to revolvers of high historical value, with NO guarantee that it will work.

The advice to hand file the barrel shoulder to align the barrel and to file the end of the barrel to provide the barrel/cylinder gap always ruins the barrel, since it’s near impossible to keep the surfaces perfectly square.
The result is tilted barrels due to uneven shoulders, and the end of the barrel not square with the cylinder.

When re-barreling a revolver, the first thing you need is a USABLE barrel.
This is much harder to get then you’d think, since a good percentage of barrels for sale at gun shows and on Ebay are defective.
Major reasons for selling a used barrel are, the barrel was defective to start with, or it was damaged during removal, using the hammer handle method.
This damage may not always be readily apparent, and sometimes isn’t revealed until the pistolsmith attempts to install it.
Damage can run from tiny cracks in the forcing cone to pitted bores, to bent barrels.
I once saw a Diamondback barrel that someone had TWISTED, probably by attempting to unscrew it from the frame the wrong way.
This wasn’t apparent until, suspicious, I checked it with a straight edge.

Cracks in the forcing cone are common, and contrary to popular opinion, a cracked barrel is almost always toast.
Cracks in steel tend to continue to spread, even if you cut the cracked end off, since cracks are a sign of metal fatigue caused by blast damage.
Some gunsmiths will attempt to save a barrel with a cracked forcing cone by setting the barrel back, but this almost always fails, and the crack continues to spread forward.

Here’s a brief description of how a revolver barrel is changed correctly:
First, the barrel is locked in a special barrel vise.
I had two, one was a small scale copy of the larger hydraulic jack type vises that gunsmiths use to change out rifle barrels.
I used this one for older round barrels like the Colt Official Police.
The second vise was large Wilton vise with heavily modified jaws.
I had sets of custom machined brass or aluminum barrel inserts that were fitted to specific makes and models.
As example I had sets for Pythons, Trooper Mark III’s, King Cobras, shrouded Detective Specials, etc.
These inserts are installed around the barrel, then clamped in the barrel vise.

The action, or frame wrench, is installed on the frame.
This wrench is a universal revolver wrench that fits around the front of the frame. It is fitted with brand and type specific hard plastic inserts.
These inserts very closely fit the front of the frame around and below the barrel area to fully support the frame.
Again, I had inserts for specific guns. I had one set for Colt “E & I” frames, another set for “J” frames, another set for “D” frames, etc.
These inserts support the frame and spread the torque over a wider area to allow unscrewing the frame without over stressing the frame and damaging it.

With the frame and barrel tightly locked up, and with no “spring” to the setup, the barrel is unscrewed.

With the barrel off, the frame threads are cleaned up with brass brushes, solvent, and if necessary are “chased” with a tap to insure clean, uniform threads.
The replacement barrel is closely inspected and it’s threads are cleaned and chased with a die if necessary.

The barrel is test fitted to the frame to determine where the front sight is and how much material has to be removed to allow the front sight to be at 12:00 top-dead-center after being torqued in place.
How much to remove is largely a judgment call based on experience.
Using a lathe or a bench trimming device, that amount of metal is removed from the barrel shoulder.
The barrel threads are coated with anti-seize compound and the barrel is threaded on the frame, everything is relocked in the barrel vise and frame wrench, and the barrel is torqued in place.
If the barrel is torqued with insufficient torque the barrel will vibrate loose.
Too much and you run the risk of pressure dimpling or constricting the bore in the thread area, or even cracking the frame.

With the barrel in place, the barrel/cylinder gap must be set.
This is done with a special cutter tool that works down the bore.
A Tee-handle rod is put down the bore and a cutter tool is attached on the end. The rod is pulled outward and rotated, trimming the end of the barrel.
Care has to be taken to insure the end of the barrel is not scalloped from uneven pressure.

With the barrel/cylinder gap set to an ideal .005”, the forcing cone has to be re-cut.
The forcing cone is very misunderstood, and even some gunsmiths have no idea it has to be re-cut and gaged or that it must be gaged at all.
The critical dimension of the cone is not it’s “length” or taper, but the outer diameter of the mouth.
If the outer mouth is too big, the gun will be inaccurate. Too small and it’s inaccurate AND will spit bullet metal.

The same Tee handle tool is inserted down the bore, but this time a cone-shaped cutter head is attached.
The cutter heads come in various tapers, and you can set a barrel for exclusive use with lead bullets by using a longer taper, or for jacketed with shorter tapers.
The factories use a good compromise that works with everything.
The Tee handle is pulled outward, pulling the cutter into the forcing cone. The handle is rotated and the cutter head cuts the cone.
Again, care is taken to prevent scalloping and the progress is checked often with a special plug gage.
This drop-in plug gage gages the outer diameter of the cone. The difference between too large and too small is very small, so gauging is done often.
The cone cannot be "eyeballed", it has to be gaged.

After the cone is cut, yet another head is attached to the Tee handle, this time a brass cone-shaped lapping head.
Valve grinding compound is applied to the lap, and the forcing cone is lapped to a smooth finish.

After lapping, the barrel and frame is carefully cleaned of all metal chips and lapping compound, and the revolver is reassembled.
The last step is firing the revolver for function, and to check accuracy off the sandbags.

As you can see, there’s a LOT more involved than first thought, and all steps are CRITICAL.
Unless you’re willing to invest quite a bit of money in custom made tooling and spend the time learning how to properly use it, attempting a do-it-yourself re-barrel job is a very fast way to ruin a good gun.

I saw the results of someone, actually a police officer, who changed the barrel of his Model 29. He clamped the frame in a vice and unscrewed the barrel with a pipe wrench. Then he screwed in the replacement barrel with the pipe wrench. He said it was just like changing a light bulb. Since it was just a shooter, he told me he didn't mind the teeth marks on the barrel from the pipe wrench. I still can't believe he was that stupid. Until the day that I die, I will never forget this stupid butchery of a fine revolver.

I'll go you one worse.

I had a guy who just couldn't wait, so he put the gun on the ground, drove his truck tire up over the barrel and used a jack handle wrapped in tape through the frame window.

He wanted to know if I could "fix that" after it failed to turn out like he thought it would.

Now, I was a pretty laid back 'smith. I'd give an honest opinion, and if they were going to screw a good gun up...I'd tell them in plain terms. I always understood that it was their gun to do with as they wanted.
However, there were a few times I wanted to grab the butchered gun and fling myself yelling, screaming, and cursing over the counter and, as an old timer told me, "Beat him until he turned orange" with the gun.

I am wanting to change my 629's barrel 8 3/8" to a 6.5". Would it be better to cut the barrel down or get a replacement? Gunbroker has a 629 6.5" NOS on there now for $150.00. What should I do??

I'd go for it. You won't need to fix the front sight. Less work and you could sell the other later for a few bucks.

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dfariswheel thanks for taking the time to write a detailed explanation! Don't think I will be replacing any barrels myself.

dfariswheel
Many thanks for that detailed explanation. I enjoyed and it is very good knowledge to pass along. Thanks for your time.

Great stuff here. Thanks for the education.

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Dave

dfariswheel,
Excellent post!
Thank you for a very comprehensive account of a very detailed and tedious process.

teesur.

I've heard of using a circular abrasive disc with a hole the size of the threads to lap back the shoulder when timing a FAL barrel. I always thought this would also be a good way to time a revolver barrel (without a lathe). Has anyone tried this?

Thanks dfaris for the great post...

The abrasive disk would cause an uneven, "lumpy" shoulder, and probably appearance issues since the shoulder almost certainly wouldn't be perfectly flat against the frame.

Brownell's does, or did sell a small bench top manual shoulder cutting tool.

Thank You, never is as easy as some people think it is.

When I need to, I will pay a competant gunsmith to do the work.

Makes me more afraid of "gunsmiths" locally.

I guess you can change the extractor (and head space) to adjust the air gap. I always understood the bearing surface (Collar) on the extractor rides on the breech face, so how do you adjust the air gap if you don't turn the barrel?

You can't move the cylinder because it's in a fixed position.

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Here I've been doing it wrong all these years. I might try it your way and not take barrels off to correct the Barrel/Cylinder gap.


Ken

The collar is that center round part of the ejector around the center pin. That collar rides on the breech face so your headspace is set by the thickness of extractor. (on revolver cartridges).

29-2 cylinder

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A forum member sent me this a while back in response to my question about how to calculate how much metal to take off of a barrel shoulder to get the front sight indexed to 12 o'clock.

A lot of interesting stuff in this thread... I hope this info helps to add to it.

"Setting the shoulder back to get the sights to index involves a little calculation with the threads. You need to know how far the barrel advances with one turn of the thread.

To determine this you take 1.000 and divide it by the pitch of the thread ( number of threads per inch). An easy example would be if you had a 20 pitch thread (20 threads per inch).

Doing the division comes up with .050" and that is how much the barrel advances per one revolution.

If a sight indexed at 6 o'clock to get to 12 o' clock, it has to rotate another 180 degrees, removing .025" from the shoulder would do that per the math.

In practice, removing .022-.023" would allow for a little crush fit to bring the sight up to the desired position and have enough tension to hold the barrel in place. If it doesn't quite index you can always remove another .001-.002". If you go too far, you have to take it a full turn and start over again".

Math was never my strong point, so figuring out how much needs to be removed from the shoulder to rotate the sight by some odd number of degrees completely strips my gears.

[QUOTE=Gunhacker;1120915]To determine this you take 1.000 and divide it by the pitch of the thread ( number of threads per inch). An easy example would be if you had a 20 pitch thread (20 threads per inch).

Doing the division comes up with .050" and that is how much the barrel advances per one revolution.
[QUOTE]


Yes your correct, but to not confuse anyone,
All S&W revolvers use a 36 TPI tap. The pitch is .0277 inch. This means 1 full turn of the barrel will move it .0277.
When I torque a barrel on, I hand tight to 10:00 position, then torque it up to 12:00 using the wrench.

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RightWinger,I'm installing a bull barrel on a 586 tomorrow and will take step by step pics for you and post here.


Ken

I have here a L Frame already stripped waiting for a barrel.First of all when you take the original barrel off,There is a ridge left on the front of the frame,If you are installing the same barrel or a factory barrel you do not have to remove the ridge.In my case here I'm installing a Bull barrel and the ridge must come off as it will interfere with the larger diameter shoulder of the bull barrel.What you do is remove just enough to take the ridge off,It must be done perfectly straight or the barrel will not seat flush.Even a couple of thou can put stress on the barrel and frame.Pic 1 is the frame(Sorry about the bad pics)


Pic 2 is the Front of the frame


Pic 3 The Frame Wrench


Pic 4 Is the barrel 1/8 before final torque


Pic 5 What it looks like in the Wrench.


I scribe a line on the barrel at 12 o'clock as you can see in the next pic.


That line is for top dead center when I torque the barrel onto the frame.Everyone does it different but I measure the top of the frame and get the center of the frame,99% of the time the screw hole for the rear sight is spot on.The next pic is the barrel installed onto the frame.




Tomorrow I'll adjust the B/C Gap,Cut the forcing cone...


Ken

Excellent job!

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My GOD, someone who's actually using the correct tools and doing it the right way.

Be still my heart.

Aussie can I ask why you didn't do the B/C gap while the barrel was off. For me that is the easy way, and most of the time I don't need a lathe.



PS Aussie, Very good job showing what needs to be done.

I also wondered how the nylon insert is removed from the frame once the barrel is installed if you use a larger the frame sized barrel as in your case, Unless there's a split in the nylon that I can't see..
Thanks for the pics & discription of the work involved to change the barrel..
Also wondered were you got those barrel blanks over in Australia?? I have a Buddy that lives in Adelade..
Thanks again!!
Gary/Hk

[QUOTE=Bullseye Smith;1123371]Aussie can I ask why you didn't do the B/C gap while the barrel was off. For me that is the easy way, and most of the time I don't need a lathe.

What I didn't show was that I always fix the endshake before I put the barrel on and while the barrel is off I measure from the front of the frame to the front of the cylinder and get my zero reading.Then on the lathe I trim the barrel to lenght,So when all is done I have a zero reading with the barrel and cylinder in the frame.Then I trim the back of the barrel to get a 3-4 thou gap and cut the forcing cone with an 18 deg cutter then chamfer.This is different but I get a better fit this way.

Gary,The inserts are split(they don't come that way).When you pull the bottom off the wrench it all comes out and the inserts fall away.I make my own barrels when I can find the Shillen blanks or order 4-6 blanks direct from Clark Custom Guns in LA.


Ken

I'm presently awaiting a reply from S&W regarding my new Model 14 revolver the front sight of which is clearly off center to the left. That is, the whole barrel is overtightened so that the grooves on the barrel do not line up with those on the top strap.

Perhaps S&W might have a look at this thread.

To further expand on this, removing from the shoulder .0277" allows the barrel to turn one revolution. One full turn is 360 degrees. So you take .0277 and divide it into 360 parts. So you know how much to take off the shoulder to turn the barrel one degree. Then multiply that number by how many degrees you actually have to rotate the barrel.

Hopefully that makes sense. It's really quite simple once you wrap your mind around it all.

Great post and the number one reason I love this place, the learning never stops.
I learned years ago that doing anything right almost always involve lots of stuff not readily visible at first glance.
Thanks for the great posts.

Absolutely invaluable info. Thanks all!

One quick question - I understand if a barrel were un-torqued and then re-torqued, it will tighten a bit further. Anyone know approximately how many degrees further?

I have a new acquisition that had a not-so-professional barrel replacement somewhere along the line and the barrel is about 4-5 degrees before top dead center/12:00. Shot groups are tight but off to the left, as you would imagine. I'm thinking that maybe a local gunsmith could just back it off and re-torque it to 12:00 without any shoulder cutting or other adjustments. (B/C gap is .004)

I would like to fix it, but I'm wondering if it would be worth the expense/effort for an old non-collectable commonwealth Victory. There's always the bench-vise and pipe wrench technique... ;-)

Thanks!

One question - what is the actual torque specs. min. and max.?

How far a barrel will rotate after breaking torque depends on the individual gun and barrel and on how hard the gunsmith turns the frame wrench.

There is no specification for barrel torque on one piece barrels.
This is a judgment call by the pistolsmith based on where the barrel shoulder contacts the frame and how far it needs to rotate to have the front sight at 12:00 O'clock top-dead-center.

What's needed is enough torque to insure the barrel won't loosen under vibration, but not so tight that there's a risk of pressure compressing the bore or bending or cracking the frame.
This is based on the pistolsmith's experience and judgment.

I'm sure S&W has a torque spec on the new one piece barrels, but that's due to the different assembly method.

I was real glad to see someone make the point of taking care of the cylinder endshake before barrel fitting. Not doing so is kinda like building a house without making sure the foundation is square & level. It's also a good time to check yoke alignment & play before trying to fit a barrel. Another issue is to make sure the faces of the cylinder are parallel and at right angles to the axis of the cylinder. I once worked on a gun with a cylinder with a 0.007" out of parallel situation-the factory fixed that part free before the lifetime warranty. Surface grinders are wonderful things

Once the cylinder is where it's supposed to be, you can measure from the front of the frame to the cylinder to determine the correct length of the barrel tenon to allow the proper B/C gap. This can be set on the lathe at the same time the forcing cone is corrected/cut.

There is a method of torquing fasteners (and barrels) where the number of degrees of rotation after contact determine the torque. Based upon observation, I believe this is the system S&W uses on one piece barrels.

Too bad Ken is no longer around, he helped quite a few folks with smithing issues.

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Sure you did

Thank-You all for taking the time and effort to explain that very interesting process.

Will Smith and Wesson still work on original model 1917 .45 acp revolvers for changing barrels/repair? I read somewhere that they won't do repairs on original 1917's anymore but do not know if that is accurate.
Anyone know?


.

The best info on that, is to contact S&W and ask them.
You get the best, latest info direct from the experts.

I do not think I would attempt to change a barrel. I believe this should be done by a gunsmith. Do not get me wrong, you might be successful in getting your revolver back to 100%, however, it is a long shot in my opinion. Let the professionals do the job for you. I have a question though; how many .375 magnums rounds would it take to wear a heavy 3 inch barrel ?

That's a question that really has no valid answer.
A S&W "J" frame revolver barrel will probably wear or crack the forcing cone a lot faster then a "K" frame barrel would.

The "K" frame barrels have a history of cracks in the forcing cone after an uncertain amount of Magnum ammo, due to the flat spot on the bottom that's necessary to allow the cylinder yoke to close. This flat weakens the forcing cone area and allows cracks to start.
Some "K" frames developed cracks fairly soon. Others have gone many thousands of rounds with no problem.

A "L" frame or especially a "N" frame S&W will shoot almost unlimited amounts of .357 Magnum ammo because of the thicker rear portion of the barrel.

The "weak link" in a revolver barrel is the forcing cone area at the rear. As long as it's intact and not cracked or heavily eroded by hot magnum loads, a revolver barrel should last just about forever.

Thanks a lot dfairswheel. I will only shoot 158 gr magnum rounds in my model 13-3, I would even keep their number down. I guess most of my shooting would be 38 specials & +P.

A S&W "K" frame will last about forever and 2 days with +P ammo.

Many of us practice with standard .38 Special or +P ammo, and either load up with Magnums for carry, or just stick with the +P.
There's a lot to be said for the old .38+P lead, semi-wadcutter, hollow point load as a defense round.
That was the round that ended the police complaints about failures to stop with the old standard .38.

Another great choice are the new "short barrel" loads. These are "light Magnum" loads made specifically for short barrel defense guns and have bullets in the 135 grain range. These fall somewhere in between the +P and full Magnum loads.
Federal makes some good ones.