Interesting Video on Fitting a Mauser Barrel

[Uncle Grinch]

I'm not a machinest, but when I came across this video, I thought it may be interesting to some of you who are like me. This is a somewhat detailed installation of the steps to fit a barrel to a M48 Mauser.

http://www.youtube.com/watch?v=1Ufes_zrZmg

[kbstenberg]

Very interesting!

[MBTcustom]

Looks like every other barreling video I've seen, with the same misinformation. No offence to the OP, but not everything is as it seems. The guy lost me when he started talking about how barrels are not drilled straight. He only says that because thats the way they look when he's done twisting the blessings out of it with his 4 jaw chuck and spider.
It's much better to use a method that allows the barrel to be held firmly, and accurately, that induces no twisting stress on it.
Honestly, if they don't know how to set up a darn barrel in the lathe, they shouldn't blame the barrel makers for a personal lack of fixturing knowhow.
Sorry, pet peeve.

[aspangler]

Looks like every other barreling video I've seen, with the same misinformation. No offence to the OP, but not everything is as it seems. The guy lost me when he started talking about how barrels are not drilled straight. He only says that because thats the way they look when he's done twisting the blessings out of it with his 4 jaw chuck and spider.
It's much better to use a method that allows the barrel to be held firmly, and accurately, that induces no twisting stress on it.
Honestly, if they don't know how to set up a darn barrel in the lathe, they shouldn't blame the barrel makers for a personal lack of fixturing knowhow.
Sorry, pet peeve.

+1 to goodsteel. As an apprentice to a local gunsmith that builds custom rinfire bench rest rifles, a four jawed chuk is NOT the way to go. Not going to reveal any secrets but a Good three jawed chuck with w spider at the back of the headstock is a MUCH better way. Just my 2 cents.

[B R Shooter]

Where the mistake is with the 4 jaw, is clamping directly on the barrel and not using a collar so the barrel muzzle can be adjusted without the bending. And where does the "twisting" come from?

Tell me the difference in using a 4 jaw, and using a set-true? As long as you use some common sense and tighten the jaws to a similar torque, they are adjusted the same.

Surely you aren't relying on a 3 jaw that doesn't adjust?

[MtGun44]

So, please (briefly) describe the proper way to put a barrel in a lathe.

Bill

[MBTcustom]

I chamber in a steady rest, but the tips of the steadyrest are used to hold a precision bearing assembly that I built myself. It utilizes Barden ceramic hybrid bearings and has a TIR of 78 millionths of an inch.
This bearing has been indicated truly concentric and parallel to the axis of my lathe.
There is a 1.4 diameter hole going through the center of the bearing and it has a small spider on it.

I set up my lathe with an adjustable 3 jaw chuck, which allows me to put exactly the presure I want on the workpiece, and then adjust it in as you would a 4 jaw.
Inside the chuck, rides a fixture that I designed that is basically a spider that is able to be adjusted for pitch and yaw.

The way chamber a barrel, is to put one end in the adjustable spider.
I use the spider bolts to get it within .010 of center.
I then slip my range rod into the opposite (tailstock) end of the barrel, and I adjust it until it is running within .001 just hanging out there. At the same time, I use the adjustable 3 jaw to keep the headstock end of the barrel running true.
Once everything is lined up and the barrel is perfectly aligned with the axis of rotation (much the way it is held by the firearm), I slide the steadyrest with the super bearing in over the barrel.
The barrel will be sagging by about .005-.010 but the spider in the steadyrest will pick it up when it is indicated in.
I then use the range rod to indicate the neck area of the barrel till the needle is as asleep as it can get (usually never stops quivering just .0001 or so)
Then I thread the barrel, verify that the alignment has not changed, drill, bore, and ream (with the truly floating reamer holder that I designed).
I have discovered that aftermarket barrels are drilled much straighter than common knowledge would lead us to believe. Do any of you really think that a Kreiger barrel is drilled 1/16" warped?!?! Do any of these people know how to read light rings?!? I've got news for you, the worst aftermarket barrel I have chambered was running out less than .004 end to end, and was capable of drilling 3/4" groups.

If you want to know why the barrels have to be adjusted so far on the back of the lathe in order to get just 3 straight inches at the front, just turn the spider bolts loose in the chuck, just take the pressure off all the spider bolts at one end of the barrel and give it a spin. You will notice that the free end is not running true. Common knowledge is to fix this by torquing the living blazes out of it until you force the end you care about to be twisted into a straight looking condition.
Hulk not like wobbly barrel! Hulk smash!
My favorite is when they get done twisting the barrel into a pretzel, and then get done explaining how badly it was drilled, they explain the advantages of threading the shank so that the barrel points up in its twisted condition, and they clock the action accordingly.

Sorry, but I have built some of the most precise mechanisms in the the world, and I just don't have any superstitions about it. I know how to indicate things so I can actually see what I am looking at, and I know how to interpret the readings I am getting and understand what is really going on.
All you have to do is observe the evidence, and don't dismiss it.
For instance, next time you get a barrel blank in the shop, look down it, and see if it is straight. Mount it between centers and indicate it. put marks on it in the high spots, and record the readings. Mount it in the lathe, and go through the normal steps. Why not put an indicator on it and see if your fixturing has done anything to it Hmmm? If you are chambering through the headstock, you can't indicate it, but you can look down it and see of it's still straight right? If it's not, why not solve that problem before ramming a reamer in there?

Shoot, I don't know everything. Each barrel is a learning experience for me, but at least I learn! We're all just experts in training.
Check what I am saying on your own equipment, and I'm confident you will see what I am saying is true. Most of us are taught by others and are trained to make the same assumptions, and to have the same blind spots, and this business is loaded with misconceptions.

[MBTcustom]

I'm probably going to regret this, but here is a picture of my system in action.
Attachment 82105
The only way you get that barrel running truer is in a zero gravity environment.

[UBER7MM]

Beautiful set up, Mr. Malcolm!

No regrets!

[btroj]

Good looking setup Tim. What was that one chambered for?

[MBTcustom]

It was chambered in 500 Jeffery. The client I was building it for decided it was too expensive to shoot, so I sold the barrel to hotguns and for all I know it's now a 50 Hushpuppy or something.
Anyway, it's as good a picture as any of what I think is the right way to do it. (at least for me it is)

[MtGun44]

Tim,

Thanks for taking the time to explain that. I get the gist of it, but unless I was sitting at the
machine actually setting up a barrel, I won't 100% follow it. It does sound like a good way to
make sure all is straight and true.

Bill

[MBTcustom]

Yeah, sorry.
The main thing is that the fact that the spiders impart twist on the barrel, is not ignored. I tried to get away with it with shims, wires, holy water, etc etc etc, and I could get it darn close, but not perfect. I always indicate the middle of the barrel, and I mark where the high spot is, and how var out it is. After I'm done setting the barrel up, that high spot had better not have moved or gotten any worse or better, or I'm going to redo the setup.
If that's what you are truly after, then let me tell you, its enough to make you get so mad that you finally just sit down and beg God for help. I couldn't let it go, and I couldn't get it right, with any traditional setup, and nobody had a better solution that didn't gloss over what I was seeing in my indicators. It was about the most frustrating thing that I have dealt with.
The good news is, I found a way to satisfy my OCDishness to the fullest LOL! You can see much better pictures of the setup in lovelife's thread in special projects:
http://castboolits.gunloads.com/show...ng-range-rifle

[B R Shooter]

I am curious what the bearing arrangement is in the steady.

[MBTcustom]

The bearing is the key to the thing. My lathe has a TIR on a turned piece of stock of .0002 inches. I wanted better.
The bearing you see there was built by me using Barden Ceramic hybrid bearings. I built it at my day job, and I rejected it because it had a TIR of 78 millionths of an inch, and I expected less than 50 millionths TIR. That's unacceptable for the purpose I was building it for, but I'm confident that it's much more accurate than anything else being used to build rifles with. Because the bearing is far away from the spindle, even though the spindle has .0002 TIR, it has little effect on the other end that I am working on, and I am confident that I am getting less than .0001 TIR on my chambers, and that is reflected by my measurements on the reamer and the chamber as it is being cut.

See I was taught to build bearings and work with steel in millionths of an inch by the best minds in the country. One feller helped write the national standards for US bearings, and the other designed the bearings in the hubbel space telescope. I bugged the living heck out of these two men, and spent hours learning from them, and finding ways to apply their knowledge on a practical level.
I have built bearings that have less than 10 millionths TIR on a 13" diameter......and that was not an air bearing. That was a ball bearing.

So you might ask, what does a rifle have to do with ball bearings? Well, you have a boolit that is spinning as it is driven in a linear motion. Concentricity is absolutely key!!!!
Most smiths get it good-nuff for use with jacketed bullets, but how do you think their rifles will do with cast lead???
The cast lead boolit is so fragile that any misalignment will show up at 100 yards.
I like to think of it like this project I worked on where I had a little 2" cup made of soft aluminum, that needed to be spun at 35,000 RPM. I told the engineer that we were going to have to get that cup running true within a few tenthousandths of an inch, if we expected it to not ring like a bell. Turns out I was 100% right, because they tried to cut corners about 3 times before they did whatever it took to make sure that cup was running perfectly true. Once we got it lined up within .0001 it stopped ringing!
How fast is you're boolit spinning?
How accurate do you think it needs to be?
At these speeds, .0002 will make a noticeable difference, because boolits don't ring like the cup, they just shoot 1" groups at 100 yards instead of bug holes.

Here's an interesting concept to munch on for a second. The cup in my illustration up yonder had a very clear "RPM threshold" below which, it would not ring, but as the speed approached it's limit, it rang louder and louder. Only by getting it to run perfectly true were we able to increase the RPMs. The more perfect the cup was aligned, the faster we could spin it.
Interesting huh?

[Willbird]

Well a normal steady, which is a plain bearing has a runout of .00000000000000000

.

I use a 4 jaw, but I make a ring out of copper wire, the ground wire from #12 house (or garage hehe) wiring, and lay it in the serrations in the jaws, and at the other end I use a spider that has gas checks on the ends of the set screws.

But as to barrels being drilled straight, nope they are not, never has been a perfect one in the history of the gun. Tony Boyer has said his most accurate barrel ever was "as crooked as a dogs hind leg". Some makers straighten them which IMHO is not a good thing, better to leave it alone as it was made.

I bought a 34" blank once for a project where I fitted 1/2 and got to keep the other half, the ID and OD ran out probably .03 in the middle of the blank, and it was from a decent barrel maker (all I will say was it was not Shilen, Hart, or Lilja). The OD and ID ran concentric at the muzzle and breech end of the entire blank.




Bill

[MBTcustom]

Bill, that's all dealing with the outside of the barrel. If you had .03 scew on the inside, then I'd say you got a janky barrel.
Also, you're not getting .0000000000 runout. You're getting whatever runout was ground into the outside of the barrel by the manufacturers belt sander, or spinner. Probably about .001
It's true that a normal steady rest is quite accurate, but again, that's the outside if the barrel, and even a Kreiger is only concentric to the inside within about .0015.
I'm talking about the inside of the barrel being perfectly straight and concentric (relatively speaking).
If I look down it, and see any more than .004 scew, I send it back. I don't care what the outside is doing, because I have cancelled it out. However, if it's running out any more than .004 then I re profile it to correct that issue (on a target rifle).

I have never seen a barrel that was drilled .030 scewed. So far the winner goes to a Remington 700 SPS with a heavy varmint barrel and it was about .025 near as I can tell. In fact, I was just in Dicks sporting goods yesterday, and had a look down the barrel of an SPS in 270 and it was the same thing. The outside was straight, the inside was bowed.

So far though, the worst aftermarket barrel I have used was a Green Mountain 35 caliber that was about .004 out on the inside. Ie, I could barely detect the bow by looking at the light rings. So far Kreiger barrels have been dead nuts, and I can't detect any bow at all. There are some fellers out there that might be better at reading light rings than me, but I'm only good to about .004 and even that is more of me just seeing that something is off in there, but it's so slight, I just can't tell where the crest is exactly.

If you want to calibrate your eyeball, just gather up all the pull offs and look down 'em. Make sure the outside is running pretty true (re-profile if you have to) and find the crest of the bow on the inside, mark where it is, and cut the barrel in half there. Then just use a tubing mike to see how much bow you were actually looking at.
Anybody who does this will find out that you can detect the scew of a barrel with remarkable accuracy.

(edit to add)
Please dont take it like I'm trying to offend any of the smiths here. I'm just reading my indicators and doing something about what I see, using the tools I have available to me.
Most of the smiths on this board were building rifles when I was in diapers. So please don't take it like I'm trying to tell you how to do your job. I'm just saying "This is what I see. This is how I do it". No offense is meant in any way.

[B R Shooter]

But how is the bearing mounted, and how is the sleeve held to the bearing? The best bearing in the world has to be mounted, and to be able to indicate a barrel within it, you need a sleeve of sorts with adjusting screws.

I've seen some setups, some homemade, some used the lathe's steady frame. I've never been satisfied on how to mount the bearing. If you used a thick plate as the "frame", pressed a bearing in it, then OK. Now you need a way to adjust. To me, to keep the loading centered, a sleeve would need to be pressed in the bearing's inner race, but you would need adjusting screws on both sides. Not that isn't impossible, but just adds to the setup. So this is the reason I asked. You are Rey confident in your setup, just asking for details if you're willing to share.

I don't agree that going through the headstock induces stress on a barrel, if done right. No stress should be used. Done properly, the barrel will simply be held rigidly on both ends with no forces induced. My interest in this is for two reasons. Short barrels that won't go through the headstock, like an XP, and big barrels larger than the headstock hole. OK, a third reason, real long barrels that would have quite a bit of overhang mounted in the headstock.

Thanks for the post.

[MBTcustom]

You don't understand. That's not a raw ball bearing. It's a bearing assembly.
I ground the housing and the spindle out of solid 416 bar stock. The outer diameter of the bearing assembly is 6". The bearing spindle is hollow and has a spider on the end of it. The bearing assembly is being held by the steadyrest journals. Great care was taken to center the bearing in the steadyrest, and to make sure it has no pitch or yaw in it. The spider tips are only used for positioning, and I have a separate sleeve that rides inside the bearing assembly to provide power to drive the bearing.

Also, if you are holding the barrel "rigidly" then you are steering it with the spiders. Every time you tighten a spider enough to actually provide power to the barrel so it can be turned, threaded, chambered, crowned, etc. You are providing enough power to steer it off center causing a warped condition inside the headstock. The only way to prevent this is to be able to cancel out the pitch and yaw being imparted by one of those spiders, and make it so that the other one doesn't matter (hence the power sleeve in my steady rest).

BTW, Kreiger guarantees their bore straightness end to end as being less than .002 TIR. If any of you are salty enough to see that with the naked eye, then you're a better barrel looker downer than me!

What that means is that if the barrel was mounted in a stress free way, there would be no discernible eccentricity on the ends, or the middle of the barrel, no matter what method is used to measure it.

[B R Shooter]

Well I didn't understand, that is why I asked. Us mortal folks don't have the means or methods to make a bearing from scratch, we rely on purchasing things like this, and making it work. As far as inducing stress in a barrel by using a spider on the outboard side to position a barrel and a 4 jaw chuck with something like a copper wire, or even a spider chuck itself, you will never convince me of that. Or, the hundreds of benchrest rifle smiths that use this method, or the old way of using a steady, and produce the incredibly small groups being shot today.

I submit to you, you should contact one or two of these renowned folks, tell them your method is hands down better and can make a more accurate chambering job that will reduce groups in a measurable way, and I'll stand corrected. If you would like some names, let me know.