Applying flutes AFTER the fact.....to be or not to be???

FBecigneul said:
Well Al,
You've said before, and you've said after, How about at the same time?

We've heard muzzle to breech and breech to muzzle. There is no set way.
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huhh?

I asked Mock a question.

He answered, well, as is his wont.

So now I've heard of boring after contouring...

what's the beef?

al
 
Al Nyhus said:
Follow the advice of the mfg. that made the barrel.

Some things in life really are that simple. ;) -Al
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Al, BRUX didn't give me any advice. They only tried to be fine folks about it and guarantee the accuracy and my satisfaction no matter what.

If the barrel's accuracy is spoiled because of it's being fluted now after it has already been completed, BRUX will cheerfully replace it at no charge. They are fine folks to offer me that. BUT I will be the one who has to pay my smith a few hundred dollars TWICE to rebarrel the rifle....never mind the time and expense wasted shipping barrels back and forth and having to develope loads again, etc. After reviewing this thread and thinking about it, I've decided to just sell this barrel and order a new one with flutes. Brux will flute it in the proper sequence they prefer, and also be making another sale to boot. I seek 5 shot 3/8" cloverleaf groups which is pretty demanding of a barrel to start with.


Thanks gents for all the input and helpful links.
 
I thought Al had a legitimate question about the "hole" being in the center of the muzzle, so I looked up the article in which I interviewed John Krieger. I was somewhat surprised by his method when he described it to me in 2006. I guess there are others who want to know more about the manufacture of premium barrels. I don't know but I would guess that Bartlein may use similar methods since both Tracy Bartlein and Frank Green once worked for Krieger. Good Shooting......James
 
It is certainly easier to contour a barrel blank that already has perfectly aligned centers created by the drilled hole. It is also easier to turn the shank portion of a barrel on centers created by the drilled hole. Final turning after drilling is the only way I can think of to ensure that the contour at both the muzzle and breech are concentric with the bore. If the hole is not straight to begin with, good luck keeping the middle concentric!
 
According to my gunsmith (COL Billy Stevens) Krieger and Bartlein have the straightest barrels in the industry. If drilling in the center of the contoured blank is so difficult, I wonder how they end up with such straight barrels? Good shooting...James
 
I've been doing a little research myself on this topic. A gun drill manufacturer I've been looking into claims it's not uncommon for a gun drill to drill straight within .0005" under a correct setup. I would think if drilling this straight becomes standard practice, there isn't much to lose machining the contour or fluting first.
 
This could be out of date, but according to my information, gun drilling of barrels is usually done so that the drill does not rotate, pressurized oil is fed through the center of the drill tube, and oil and chips evacuated through a groove in the outside of the tube that is positioned at the bottom of the tube. There are exceptions to this, and at the time that I was told, before Bartlein was in business, if I remember correctly, Krieger and Douglas counter rotate the drill (The blank rotates in one direction, and the drill in the opposite.). I understand that this is at a different speed than the blank. I was told that this is done to reduce the cumulative effect of gravity on the straightness of the hole, when drilling horizontally.
 
all my barrels were fluted by my gun smith while he was chambering them.

they all shoot well under .25 moa
 
Don Nielson said:
I think you will find thats .0005 per inch of depth. Don
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Straightness of .0005 per inch of depth is confirmed. My understanding is this is a "common" accuracy for the gun drill process. I also found out there is straightness to be gained in the reaming process, where certain processes can commonly achieve .0002 straightness per inch. That would equate to only .0048 over a 24" blank. That being said, I've had some supposed match barrels from some larger barrel maker names that was a far cry from this "common" straightness accuracy.
 
Think about this logically. If you flute a barrel before it is contoured would you not loose some of the depth of the fluting after the final contour is reached. Since I live not that far from Hart Rifle Barrels, I got their process. The barrel blanks are first bored and then rifled. Contour is done after the rifling process, and then they are lapped. If fluting is required it is done after the couture and the barrel is lapped again
 
Boyd Allen said:
This could be out of date, but according to my information, gun drilling of barrels is usually done so that the drill does not rotate, pressurized oil is fed through the center of the drill tube, and oil and chips evacuated through a groove in the outside of the tube that is positioned at the bottom of the tube. There are exceptions to this, and at the time that I was told, before Bartlein was in business, if I remember correctly, Krieger and Douglas counter rotate the drill (The blank rotates in one direction, and the drill in the opposite.). I understand that this is at a different speed than the blank. I was told that this is done to reduce the cumulative effect of gravity on the straightness of the hole, when drilling horizontally.
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Boyd,

there are two types of gundrills. Machines that rotate the workpiece, and machines that rotate the drill. Workpiece rotators are the type that are typically used in making barrels. There is no benefit to counter rotating the drill on this type of machine. Think about it. Yes, gravity causes the drill to droop in a downward trajectory. But from the perspective of a barrel spinning at 3000rpm, downwards at any given moment is a different direction, and the error is cancelled.

On the other hand, on a gundrill that rotates the drill and feeds it into a stationary workpiece, there is a benefit to be gained from counter rotation. From the perspective of a stationary workpiece, gravity would always be pulling the drill in a constant downward direction. In this type of machine the drill would be rotated at 3000 rpm (depending on the size of the hole), and the workpiece is counter rotated at perhaps 100rpm. High end, automated drills are often made in this configuration. The advantage of this type of machine is that the barrel blank is rotated slowly enough that it doesn't try to play jumprope, and remains in it's natural state; there is no springback when the minimal effects of centrifugal force are stopped.
 
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Francis,
Do you know of any barrel makers that drill vertically? Actually, it would seem that drilling up (bringing the workpiece down), might be the best.
Boyd
 
Boyd Allen said:
Francis,
Do you know of any barrel makers that drill vertically? Actually, it would seem that drilling up (bringing the workpiece down), might be the best.
Boyd
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The most accurate (straightest) way to gundrill a small, deep, hole is to rotate the drill and the workpiece. We used to do a lot of that type drilling. The net cutting speed (SFM) would be the same as just rotating the drill.
 
Thanks Jerry,
The fellow that told me about counter rotating said that he first ran across it when he was part owner in a business that did work for the aircraft industry. They were having trouble holding straightness tolerances for some long hydraulic cylinders (for landing gear, if memory serves), but their competitor did not seem to have the same problem. Since he was a skilled machinist, and he was unknown to the competition, he took a job working for them to find out how they were doing the work. He said that what they were using looked like very large lathes fitted with headstocks at both ends, turning both the drill and the work, at different speeds.
Boyd
 
Vertical drill?

I was talking to Jim Meyer of CT one year at the SS. If memory serves me (which it does less and less these days), he told me that he used a vertical drill. At one time he made actions. James
 
James M. said:
I was talking to Jim Meyer of CT one year at the SS. If memory serves me (which it does less and less these days), he told me that he used a vertical drill. At one time he made actions. James
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Jimmy "NASCAR Terry Labonte" Meyer made his last action in 1998. I bought it in 1999 and it was not serial numbered till then so I got to pick the number. He offered Aaron Calton and I the complete action building tooling for a very small sum. I think that tooling is still in his Torrington, CT shop.
 
Boyd Allen said:
Francis,
Do you know of any barrel makers that drill vertically? Actually, it would seem that drilling up (bringing the workpiece down), might be the best.
Boyd
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Boyd

Someone told me the Sharps Rifle Co. in Big Timber MT. drilled their barrels in the verticle position.

Hal
 
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