Machining heavy barrel to a mid contour barrel?

Ghunter

Ghunter

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Hey there. I’m not a gunsmith or machinist by any means. Therefore here is my question.
Seeing how hard it is to find a mid contour barrel for Ruger 10/22 I starting thinking about getting my heavy barrel .920 machined down to like .700? My buddy is not a gunsmith but a professional machinist.
Is this doable? Any tips or suggestions for getting the job done?
Thx
 
I had that done with a heavy contour to 23" heavy sporter 260 rem on an aftermarket barrel. Gunsmith had to take very fine cuts and made a lot of steel wool to not impart heat stress in the metal. Mine shoots very well indeed after the profiling as it did in competition profile. Time intensive process likely not to be a cheaper option, unless your buddy is working for beverages. Perhaps deep fluting would be an option to consider in reducing weight for a heavy sporter function. In a 22lr, the harmonics may not be such a major issue where metal stress is of concern. But not sure on that as any stress may change the barrel harmonics. Just hope it is in a repeatable way. It would be a roll of the dice on a factory barrel IMO.
 
I have had my gunsmith turn down and or flute multiple hammer forged, cut and button rifled barrels and all have shot well.
 
Tokay444 said:
If it’s a cut rifled barrel, no problem. A hammer forged or button rifled barrel would twist and bend. Don’t bother. Too much stress in the barrel.
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How do you think manufacturers profile a button-rifled barrel? After drilling, reaming, and rifling are finished. Turning it down further is exactly the same process. Hammer forged is profiled during the rifling process so you might be right with that one. But they're generally stress-relieved after that, AFAIK.
 
Fine cuts in short segments close to the chuck to avoid barrel flexing and getting out of balance. Theres some videos of this on YouTube. Or cut from opposite sides at the same time, not your average lathe ability.
I turned a 8x57 stepped barrel down on a drill press useing two course files on opposite sides at the same time. And many many cups of coffee. If a turd kicker like me can do it, a real machinist would not have a problem.



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Tokay444 said:
If it’s a cut rifled barrel, no problem. A hammer forged or button rifled barrel would twist and bend. Don’t bother. Too much stress in the barrel.
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How did you come up with this "myth"?

I have turned hammer forged barrels, button rifle barrels and cut rifled barrels down since 1967. The only barrels that warped were a couple of Ackley barrels that had not been properly stress relieved. Ackley replaced those (this was in 1968) and I have not encountered a problem since then and I have turned hundreds of buttoned barrels and hammer forged barrels.
 
guntech said:
How did you come up with this "myth"?

I have turned hammer forged barrels, button rifle barrels and cut rifled barrels down since 1967. The only barrels that warped were a couple of Ackley barrels that had not been properly stress relieved. Ackley replaced those (this was in 1968) and I have not encountered a problem since then and I have turned hundreds of buttoned barrels and hammer forged barrels.
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This is one of those myths which simply will not go away. This isn't helped by some makers of cut rifled barrels who go out of their way to perpetuate it. When a barrel warps, it is because the material wasn't in a stress-free state. Because of the potential for induced stress, stress relief is part of the manufacturing process for button rifled barrels. Because cut rifling does not induce stress, the step is omitted by most makers of cut barrels. If the material is stress free, this is all well and good but even material which is purchased as being "heat treated and stress relieved" is not always stress free. Material which was not spec'd as HTSR, will likely be stressed and will warp.
In my experience, hammer forged barrels are stress free. I have never had one which warped at all although I have turned some (mostly Remingtons) which started out crooked. I have had four barrels which warped so badly they had to be straightened during the process. Two were cut-rifled (Bauska) and two were buttoned (King). The common denominator was that none were stress relieved.
 
I don’t have to do it know that it can cause a problem. My background and education in manufacturing tells me it’s not a good idea.
Frank Green at Bartlein says he wouldn’t even flute a button rifled barrel for the same reason. There’s no way to quantify just how stress relieved the barrel is.
 
rifleman762 said:
How do you think manufacturers profile a button-rifled barrel? After drilling, reaming, and rifling are finished. Turning it down further is exactly the same process. Hammer forged is profiled during the rifling process so you might be right with that one. But they're generally stress-relieved after that, AFAIK.
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If it were me, I would profile the blank before pulling the button.
 
Tokay444 said:
If it were me, I would profile the blank before pulling the button.
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There is a problem doing it that way - resistance to passage of the button varies with the blank diameter. Springback is not consistent. Consequently the buttoned bore dimensions vary from end to end.
This is why blanks are cylindrical when buttoned, then stress relieved, then contoured.
 
The barrels that I have had warp were rolled octagon barrels. The rolling to shape left stress in the surface of the barrel and when you remove the surface, the inner portion of the barrel is no longer held in a straight line. If you are lucky, you can bend the barrel back straight as well as put the curve in a vertical plane rather than horizontal

cheers mooncoon
 
Tokay444 said:
I don’t have to do it know that it can cause a problem. My background and education in manufacturing tells me it’s not a good idea.
Frank Green at Bartlein says he wouldn’t even flute a button rifled barrel for the same reason. There’s no way to quantify just how stress relieved the barrel is.
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You will know on the first light cut if it starts to become a crankshaft of if it stays straight... and I have not encountered one since 1968...

Does your background tell you about stress relieving barrels?... how all the barrel makers do that... I believe it is one of the critical steps in making a quality barrel.
 
Tokay444 said:
The only way to quantify it is to destroy a barrel and look at the martensite/austenite grain structure under a microscope.
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Gimme a break!

No one needs to quantify it... just go ahead and turn it down... it will either turn down with no problem (most of the time) or it will warp at which point you stop wasting your time.
 
Tokay444 said:
I don’t have to do it know that it can cause a problem. My background and education in manufacturing tells me it’s not a good idea.
Frank Green at Bartlein says he wouldn’t even flute a button rifled barrel for the same reason. There’s no way to quantify just how stress relieved the barrel is.
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And there you have it. "Frank Green at Bartlein" says.... Bartlein is a cut rifled barrel maker.

You don't have to do it to THINK it can cause a problem. When, in the course of your manufacturing, you have encountered warping due to internal stress in material and worked out how to deal with it, you will be able to say under what circumstances it will or will not cause a problem. If you have not turned or milled barrels, you don't KNOW. Your comment about profiling before pulling the button underscores this.
Not all hammer forged barrels are profiled during the rifling process. I have profiled cylindrical hammered blanks several times.
 
Tokay444 said:
I don’t have to do it know that it can cause a problem. My background and education in manufacturing tells me it’s not a good idea.
Frank Green at Bartlein says he wouldn’t even flute a button rifled barrel for the same reason. There’s no way to quantify just how stress relieved the barrel is.
Click to expand...

I just obtained a very accurate Savage 12 223 with a button-rifled, fluted barrel. Some of you may not believe me but I shot a 5-shot 0.357" group with my very first round of load development. Using once-fired brass from a semi-auto, full length sized. I loaded that ammo before I even got the gun in the mail last week :). And I used Lee dies...gross, eh?

Sounds like having a final profiled barrel that is free of stress is more important than the rifling method used. Stress relieving does decrease the hardness and tensile strength of steel. And having the steel too hard before rifling is a problem for the button rifling process. So it's a balancing act.
 
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