Barrel straightening

[rbertalotto]

Proof is in the pudding...........Just look how accurate those Savage factory rifles are!

[B R Shooter]

Does Kreiger straighten their barrels? I think not.

[jmh54738]

Proof is in the pudding...........Just look how accurate those Savage factory rifles are!

What procedure does Savage use? Are the barrels straightened as a final step or are they straightened and then stress relieved? I thought that straightening was done before rifling so that the light reflecting through the bore could be used to determine the straightness or lack thereof. I just don't know

[rbertalotto]

The whole Savage thing is very weird.........and it doesn't make a bunch of sense to me or to most knowledgeable folks on boards such as this.........

The barrels are drilled, and then reamed, then button rifled on some VERY old P&W machines with a super secret cutting oil (this was the only thing during the whole tour they would not disclose)

Then they are contoured and stress relieved......From here they are straightened....As far as I know, no stress relief........They then go to chambering.

The amount of straightening is not noticeable to the naked eye from the external of the barrel. But it is VERY noticeable when looking down the bore.

I chamber all my barrels "through the headstock". Because of this method, I can look down the bore while the barrel is spinning. I've NEVER seen a straight bore. Not once........All bores from every manufacturer have curves in them. Obviously, most manufacturers care not about this curvature. Savage is convinced it is one more arrow in its quiver leading to their superb out of box accuracy.

[30calflash]

It looks like the only way to find out is to try it. Once it gets to the point of being straight the stress factor may kick in. I've read about rifles changing POI when they get hot. Maybe it takes a dozen rounds, a string of rapid fire or maybe 100's of rounds. These are barrels that were never bent, just factory rifles. If stress became a factor would a cryo treatment fix it? Or would the barrel 'bend' due to the treatment?
The idea of heating the barrel to a certain temperature seems like an iffy proposition. At least to me. But heat to some point is used in cryo processes, I believe.
Using a moderate cast load would probably help keep stress to a minimum versus shooting jacketed loads at high velocity.

[B R Shooter]

I've owned a Savage 110 single shot in 220 Swift. It did indeed shoot very well for a factory gun. And most of them do! But I'm not so sure the barrel is the key here. I looked down the bore of my Savage and it was awful! Not speaking of whether it was straight or not, the rifling and interior finish was rough to say the least. But the damn thing shot well.

I think the action and floating head has more to do with the accuracy than the barrel.

[leftiye]

I have a old Ruger that with the original barrel would place the first four in a line an inch apart horizontally, the next four in a line an inch apart vertically, and after that it would then shoot nice groups. I'd never seen anything that would wait for me to shoot the first eight shots, so I got a Titus barrel for it.

I would be very prone to thinking that if you bend a barrel it will stress the given barrel (almost by definition). Therefore it would seen smart to relieve it afterwards. The fly in the ointment is that when you relieve the stress, the bends come back! Kinda makes you wonder?

The bends that rbertalotto describes wwere probly put in by the gun drill. Also, button rifling makes a lot of new internal stresses in a barrel. It may be witch craft, but some manufacturers do produce accurate barrels, and wise people buy those brands - even if nobody can tell them exactly why those barrels shoot. Just think what hammer forging does to a piece of barrel steel (and then wonder why those barrels ever hit anything).

[uscra112]

Did he say that his barrel is bent THREE INCHES? Bending it back is going to leave some seriously fatigued steel, I would think. It's already stretched on the outside of the bend, and now you're going to stretch the other side by bending it back. It'll be an interesting experiment, but I don't want to be too close to it when it's fired.

Also, all steel has internal stresses in it from the rolling process. I worked for many years in the machine tool business, and saw time after time how a long part being ground straight on a big way grinder would "walk" all over the place, just from a few thousandths of an inch being licked off one side. Our guys had all sorts of strategies to mitigate this. It was a bit of a black art. Same thing for a barrel made from a steel bar - the drilling takes out metal that's under some non-uniform stress or other, and the remaining metal "springs" out of true in response. The best stress relief is age, but it takes years for most ferrous metals to stabilize. There was an artificial aging process that subjected the metal to strong vibrations for a period of days, and it did seem to work. I've never heard of it used on barrels, but it might be worth researching.

A trick some mechanics know for straightening a piece of steel wire is to stretch it. It would take a monstrous press, but I wonder if stretching a blank prior to drilling would do any good?

[eagle27]

I straightened a 270Win barrel once that had been accidentally slashed when the owner was cutting a track in the bush. The barrel was bent like a banana with a gouge of metal where the slasher blade hit.

I held the barrelled action between centres on my big old flat belt driven lathe and used the tool post to push the bend out of the barrel. I had to take it past centre near the end of the process to allow for spring back. Got it spinning true and sighting down the bore showed a perfect circle. Carefully hammered the gouged metal back into place (about half way along the barrel), reassembled the rifle, loaded up and put bullets down range. Perfect result and this particular rifle went on to shoot as accurate as it had always done and take many an animal along the way.

30calflash, it is worth a try if nothing else.

[mroliver77]

Here is a video of the process.
http://www.nij.gov/training/firearms...4.flv&slides=0

Personally I am not equipped with a press yet. If I had this p;roblem I would seek to either rebarrel or check with John Taylor on a price for his service. It might be cheaper than you think to send a stripped barreled action to and fro and get the work done.
Jay

[Multigunner]

I straightened a badly bent Remington .22 rf rifle barrel many years ago, by using a method I had used to straighten bent aluminum arrow shafts.

After roughly getting the worst out with a dead blow mallet I laid the barrel on a very flat slab of concrete then I first took a thick plank with a concrete block on top for weight and rolled the barrel back and forth till almost straight, then finished up rolling it with a slab of steel about 3/4" thick and 4" wide.


The British had originally carefully straightened all Enfield barrels, but when wartime shortages and lack of skilled hands cut into production they established that so long as the last six inches of the bore was straight the rifle should shoot straight. After that they used a six inch long gauge at the muzzle and only straightened a barrel ( or set it aside )if it didn't pass that gauge.

This is one reason that many sporterized No.4 rifles that have been shortened don't shoot so well as you might expect.

I've glad to see that Savage still honors the old methods. Most of my long guns are Savage products. Some like my 23B look a bit odd but they all shoot like precision instruments.

[oldmossback]

Resurrecting this old string I was wondering what I should do with my old barrel.
It is from a Win. 92 that I had relined and that gunsmith when stuffing the sleeve in the old barrel, bent my barrel, down between the rear sight slot and the under slot for the forarm screw.

He tried to straighten it but was not confident that it was straight.
I replaced the barrel and 30 years later I sold the gun but still have this barrel.

Recently reading over on the CAS forum I got the idea of building myself a 1873 from parts. The threads are the same for both rifles so I am considering using this barrel......maybe.
I like doing this sort of thing as I built up a Harley chopper about 35 years ago from scratch and have done a couple of other projects like this, including building a pistol from a kit.

After reading all the above comments concerning barrel straightening, I pulled this old barrel outta my closet.

How does one tell for sure the bore is straight? I tried the Savage method of using a white wall to view the bore, I do not see any curve or bulge. But the muzzle end is easier to see than the breach end so I reversed the barrel to peer down the muzzle and still it does not seem bent toward the breach end.

Now on the outside, I definitely can see ridges, wrinkles or ripples where the old outer barrel was bent and possibly wrinkled pushing in the sleeve. Running a metal straight edge I can feel the bulge around the slot where the forearm slot is. And can see it after several swipes of metal to metal.

However this is not all away around. The flats on the top side where the stampings are, is smooth. Just 3 or 4 of the flats on the underside have ridges or wrinkles.

So if your not asleep after all this, I have this question. IS this barrel worth saving? How do I determine if the sleeve is straight and has no bends? Or does this matter on the breach end?

Oldmossback

[RoyEllis]

Best way I know of personally to check for straightness inside, is to run a pc of strong yet flexible wire thru the bore and attach it to a stick or fiberglass rod so you end up with what looks like a primitive bow with the barrel around the string. Hold up to light and move the wire string around to different sides of the barrel. You'll quickly see any bent spots as the wire will touch on each side and leave a visible gap beneath at a low spot. Learned that trick from an old man I used to watch build black powder rifles when I was a kid. Sure wish I'd spent more time & learned all I could from him when I had the chance to do so.

[jblee10]

I think there is a great difference in straightening a newly manufactored barrel, and straightening a "bent barrel". A new barrel may have a slight curve. And I think a new barrel is straightened so it will shoot close to where the sights can be adjusted. I doubt that it makes much difference if the barrel is 100% straight or 98% straight. It just needs to be good enough to throw bullets under the sights, and throw them the same way each time. But a bent barrel is something else. I think a "tube" that is badly bent and then straightened will deform bullet and never throw bullets consistently. Just my thoughts. I could be way off target myself.

[Frank46]

I read an article where a guy rebent his M1 op rod using a workmate one of the folding tables. He made up some blocks and by adjusting them and cranking the two handles put the correct bends back in. The idea of heating a barrel is not really new. We had a rather big boiler explosion and the I beams behind the boiler were badly bent. What they did was wrap these ceramic blankets and apply current to them and get them to a certain temprature and hold the temp for some time. Then let them cool naturally. This had to be done a bunch of times to let the beams assume the position as when they were made. And last but not least lindsey books had a book that shows how the brits straightened barrels in WWI. Basically lead blocks and a hammer. Frank

[waksupi]

You can tell if a barrel is straight by looking at the light bars in the bore. If you don't know what it looks like, look at a shotgun barrel first, you will see the concentric rings the full length. Same thing in a rifle barrel, but with rifling grooves. If they wander to one side of the barrel, it is bent.
Barrel makers will straighten a barrel, before profiling.

[rbertalotto]

If the "gunsmith" used that much force to insert the liner that he deformed the barrel, I'd suggest the whole thing is a tomato stake. These liners should slide in with maybe a few light taps from a rubber mallet. No force is needed. If you are going to all the work of building a nice 1873, just buy a blank from Green Mountain or find another used barrel on E-Bay.

[DLCTEX]

20 or so years ago I watched a piece on TV about a barrel making company and they showed how the barrels were straightened. The man sighted through the barrel to find the bend and any bent ones were whacked over a lead anvil. The inertia straightened the barrel. I have since used the method to straighten rods and pipes, but never a gun barrel.

[oldred]

If you think about it a barrel actually does not have to be straight as long as the sights will align with the point of impact, the bullet will fly in a straight line (not accounting for drop) regardless of the path it takes to reach the muzzle. I am talking about minor curves/bends that a person might see by looking down the bore at a white background and not a gross bend that's obvious by looking at the outside of the barrel. With a badly bent barrel or one like oldmossback is describing I would be more concerned about bore concentricity than straightness, a slight bend or curve can still shoot very accurately (I doubt if many barrels are perfectly straight) but a spot in the barrel that's out-of-round or swelled/constricted will be very detrimental to accuracy. If a bullet is damaged by being squeezed through a tight or out-of-round spot in the bore it will not fit properly in the remaining length of the barrel it has to travel. If a barrel is bent very badly then it may be possible to get it straight BUT the bore is likely to be damaged, a tight bend over a small radius will likely result in a tight spot in that area after straightening. This tight spot will result in the bullet being too small to fit properly in the remaining section of the barrel which would likely result in poor accuracy.

[MBTcustom]

Just my 2 cents worth, based on observations in my shop and on my range.

Most factory barrels are not straight. This is a fact. Savage barrels however, (despite being quite liberal on groove and bore diameter, and chamber dimensions) are usually pretty strait. I do think this has a lot to do with their accuracy, at least for the first five shots, afterwards, they heat up and try to go back where they were before the straightening process.

Most after market barrel blanks are exceedingly straight. Less than .002 is very common regardless of what the outside of the barrel is doing. I can read light rings, and spinning the barrel in the lathe enhances the accuracy with which I can see the straightness.
There is a lot of bad information going around out there about how, even match grade barrels, are not drilled straight (coming from "smiths" that use rigid spiders to hold the barrels through the headstock of the lathe, and have no real grasp of accuracy, other than what they were told by another misinformed smith that does not understand either).
Even the cheap Adams and Bennett barrel blanks (Green mountain now) from midway average less than .002 TIR stem to stern.

A barrel is a very floppy thing, and easily influenced by the slightest pressure. However, in order to bend a barrel so that it takes a set, a pretty good amount of pressure is required. Steel doesn't take a set all the way through the pressure application. Up until the point where it will begin to take a set, it will spring right back to the original place with no effect whatsoever (Archers who shoot aluminum arrows know this very well). Once the barrel crosses that threshold, it's just a matter of pushing it exactly how much you need it to move and no more.

Have I straitened barrels? Certainly! Do I make a habit out of it? Absolutely not. I am of the opinion that there are so many good barrel makers out there, that life is too short to mess with crummy barrels.

Now, as to the effect that a bent barrel has on the trajectory of the boolit: Often, while a bent barrel is capable of extremely good consistency, it throws the projectile in a sort of helix that stabilizes down range. If you shoot on a good day with the sun at your back at long range, you can often see the boolit "spiraling" as it flies down range. However, at any given range, the shots will impact in nice little groups, which makes it so that most shooters never realize that the bend in the barrel throws the boolits in a helical pattern, kind of like an arrow with one feather missing.