Barrel Indexing,,

Friend Don:

Friend Don:

I quote from you....... "I did not mean to suggest that the barrel "leaked" from gas blow-by, as I can now see that it was probably interpreted that way."

Don, I understood your meaning when you used the term leakage....we are on the same page....

Your barrel exhibits a problem that sometimes can be corrected....

I made you an offer of assistance.....you of course aren't required to accept it...

If you ask why I made the offer? I love accuracy.....it's that simple.

When a barrel shoots big old round groups, it's a dog.....when a barrel shoots 4 through one hole, then fliips one ever group or two.....sometimes there's a killer, (hummer) hidden there, with a little adjustment.....

Your friend, Bill Calfee
 
Pete

Have you ever taken a Factory Barrel to a Gunsmith, with an action, and told him you wanted it fitted, with the sights, and Factory Lettering, in the correct position. Sure,he will do it, for twice the money........jackie
 
jackie schmidt said:
Have you ever taken a Factory Barrel to a Gunsmith, with an action, and told him you wanted it fitted, with the sights, and Factory Lettering, in the correct position. Sure,he will do it, for twice the money........jackie
Click to expand...
With a concentric sleeve, threaded both ID and OD, with different pitch threads - one matching the receiver, the other matching the barrel. This sleeve can be either shimmed off of the barrel shoulder, or trimmed to length. The result is the ability to index the barrel without having to recut the chamber, and without changing headspace.
 
Vibe said:
We can continue in PM if you'd like, but I'd like to know why not? It's not a unique application of differential threading.
Click to expand...

I think in order for "differential threading" to work in this barrel indexing application, 2 lock nuts would also be required to lock the sleeve and barrel to the action at the correct length............an awfull lot of hardware crammed into very little space.............Don
 
Don said:
I think in order for "differential threading" to work in this barrel indexing application, 2 lock nuts would also be required to lock the sleeve and barrel to the action at the correct length............an awfull lot of hardware crammed into very little space.............Don
Click to expand...
Not at all. The sleeve is torqued (or locktited) to the barrel tenon shoulder, thus locked, and the barrel (with sleeve installed), is then torqued to the receiver, thus also locked. With no jam nuts.
It does require that the barrel tenon itself be a bit smaller or the receiver threads a bit larger or both.
 
OK, since this old hoss is back up and running :p:p

GENE....... it's been three yrs. Are you still drooping your barrels? Indexing to 6 O'Theclock versus 12:00?????

Reason I ask is, this indexing thang is kinda' addictive :) I can perty much point the barrel wherever I want it on the hunnerd yard target now and I've found a weird thing.

Hear me out now.....

First of all, YUP! they're 'way off! I deal with long barrels, a lot of them fluted and lighter contours..... the're predictably OFF by like a foot or more at a hundred, not at all hard to deal with, predictable and repeatable except for one thing....

hear me out now......and search your memory banks

I can point LEFT, I can point UP, I can point RIGHT...... but it seems to me that as the rotation goes over and down the poi seems to start compensating or flipping up.

In other words Gene, a 5:00 pulls up closer to 3:00 and a 7:00 index will impact closer to 9:00. 6:00 dead-center down also seems high.

Luck??? (I have only done two) or have you found anything similar? Do you feel that 6:00 index pulls high a little?

BTW, I'm not going to spend much time with this anymore, but in my "repeatability experiments" phase I've been able to thread right up to the shoulder and then index in-in-in incrementally and end up with a parallel section for the recoil lug to set on. And in the process watch the barrel travel the clock! (Of course some can just insist I cut the tenon crooked! LOL)

Re-shoulder
Re-chamber
Re-cut for extraction

I'm DONE with my experiments for a while but value your opinion if you have one on this subject.

And any of you other guys!!! Try it, report back...

BTW, I ordered some extra long Palma tapered barrels with extra long shanks for this experimentation so when I'm done I'll still have something usable. Even if I buggerup...

al


I don't know how that frownyface got there????

ignore it!
 
Hi Al, how ya' doin' buddy?

alinwa said:
OK, since this old hoss is back up and running :p:p

GENE....... it's been three yrs. Are you still drooping your barrels? Indexing to 6 O'Theclock versus 12:00?????

Reason I ask is, this indexing thang is kinda' addictive :) I can perty much point the barrel wherever I want it on the hunnerd yard target now and I've found a weird thing.




Hear me out now.....

First of all, YUP! they're 'way off! I deal with long barrels, a lot of them fluted and lighter contours..... the're predictably OFF by like a foot or more at a hundred, not at all hard to deal with, predictable and repeatable except for one thing....

hear me out now......and search your memory banks

I can point LEFT, I can point UP, I can point RIGHT...... but it seems to me that as the rotation goes over and down the poi seems to start compensating or flipping up.

In other words Gene, a 5:00 pulls up closer to 3:00 and a 7:00 index will impact closer to 9:00. 6:00 dead-center down also seems high.

Luck??? (I have only done two) or have you found anything similar? Do you feel that 6:00 index pulls high a little?

BTW, I'm not going to spend much time with this anymore, but in my "repeatability experiments" phase I've been able to thread right up to the shoulder and then index in-in-in incrementally and end up with a parallel section for the recoil lug to set on. And in the process watch the barrel travel the clock! (Of course some can just insist I cut the tenon crooked! LOL)

Re-shoulder
Re-chamber
Re-cut for extraction

I'm DONE with my experiments for a while but value your opinion if you have one on this subject.

And any of you other guys!!! Try it, report back...

BTW, I ordered some extra long Palma tapered barrels with extra long shanks for this experimentation so when I'm done I'll still have something usable. Even if I buggerup...

al


I don't know how that frownyface got there????

ignore it!
Click to expand...





Al, sorry about taking so long to respond to your post. I would like to say it is because of my hectic schedule and the overwhelming demands of my big international multi-billion dollar business, blah, blah, blah, but I'd be lying like a dog. :eek: The truth is, I'm just getting old and lazy. :rolleyes: There; how's that for being honest? :p

Barrel indexing? Yep, it works; sometimes. :rolleyes: If all barrels were perfectly straight, there would be no need for indexing. But, as you know, few barrels are perfectly straight; however, I must say, the barrel makers of today are doing a better job than ever before.

Generally speaking, the reason our barrels vibrate or whip in the vertical plane as the bullet travels down the bore is because they are hanging out into space suported by only the front receiver ring. The muzzle droops because of gravity and the forces generated by firing cause the muzzle to droop even further as the middle of the barrel humps up setting into motion a vibration mostly in the vertical plane. If the barrel is perfectly straight, there will be very little if any vibration in the horizontal plane, but,,, if the barrel has some built in curvature and that curvature happens to be oriented in the horizontal plane; hoo boy! That barrel will drive you crazy. :mad: But wait; there's hope! :)

If you will re-index the barrel and 'hide' the built-in curvature so it blends in with the natural gravity droop the barrel will quiet down in the horizontal plane. You can tune out the vertical with the load or a tuner and that bad barrel will sometimes water your eyes with how well it shoots. :eek:

One thought to leave with you and that is, A barrel can never be more than ninety degrees out. That's right; so even in the worst case scenario, we will never have to rotate the barrel more than a quarter turn. :cool: "But how do you do that?" you ask.

We will get into that in the next post. :)

Questions? Comments?

Later,

Gene Beggs
 
Muzzle up or down?

In regards to barrel indexing,

"Should the curvature be pointed up or down?"

After much experimenting I have concluded that it doesn't matter! At least not from an accuracy standpoint. What we are trying to do with barrel indexing is eliminate or at least, minimize vibration in the horizontal plane.

During early experiments, I tested four positions of the barrel which involved lots of time at the lathe. Then, with the differentially threaded bushing, I tested eight positions and was surprised when I found that all this was a waste of time! :eek: Once the vertical orientation in which the barrel shot best was found, it did not matter whether the muzzle pointed up or down. I finally realized that the farthest a barrel could be out was a quarter turn. Real rocket scientist; huh? Only took me a couple of years to see that. :eek: Sometimes I worry about myself; can't see the forest for the trees. :p

Later

Gene Beggs
 
Gene Beggs said:
I'm not sure, but I'll be looking forward to the results of your tests. Keep us informed and thanks for resurecting the thread from '08.

Gene Beggs
Click to expand...

Gene - the only "equipment" I have for running this test is the computer and the software. All of the data will have to be generated and collected by folks like you and a few others on various forums. I'll be more than happy to run the data through the statistical program - but I, personally, have no way to do anything else.
 
I’ve mentioned this information in prior threads. I want to mention it again here just for thought.

In the late 1980’s, the military’s artillery and tank barrels became much more accurate than before. The need for improvement was based on the fact that the munitions, computers and the ability to target had surpassed the accuracy of the ability of the firing platform. Recoil mechanisms and footprints were looked into but the primary area for improvement was the barrels and this is what the military had come up with.

All barrels for artillery and tanks are placed in a fixture. A frequency is induced to the barrel and monitored by computers. The barrel is then tuned for maximum accuracy. All barrels have their droops and curvature facing down in the vertical plane. Now what frequency and exactly how they turned the barrels is classified. But when I asked about the droop/curvature being pointed down, the answer was: During sustained firing, the additional droop of the barrel (which will affect point of impact) was more predictable when the barrel was facing down than up. He stated that it was most important that the curvature was not in the horizontal plane as unpredictable wind drift and unpredictable vertical impact would occur. If the barrel was in any plane other than the vertical, as the barrel heated and drooped, it would always droop at an angle which effect horizontal and vertical dispersion.

How much if any of this pertains to point blank BR, I don’t know.

Hovis
 
There is quite a difference between having sights and writing align properly and simply indexing a barrel that does not yet have any writing or sights on it. Once the high and low spot is found and marked, it would seem relatively simple to me to index that mark before the chamber and cone are cut, or am I way out on a limb here ?
 
HovisKM said:
I’ve mentioned this information in prior threads. I want to mention it again here just for thought.

In the late 1980’s, the military’s artillery and tank barrels became much more accurate than before. The need for improvement was based on the fact that the munitions, computers and the ability to target had surpassed the accuracy of the ability of the firing platform. Recoil mechanisms and footprints were looked into but the primary area for improvement was the barrels and this is what the military had come up with.

All barrels for artillery and tanks are placed in a fixture. A frequency is induced to the barrel and monitored by computers. The barrel is then tuned for maximum accuracy. All barrels have their droops and curvature facing down in the vertical plane. Now what frequency and exactly how they turned the barrels is classified. But when I asked about the droop/curvature being pointed down, the answer was: During sustained firing, the additional droop of the barrel (which will affect point of impact) was more predictable when the barrel was facing down than up. He stated that it was most important that the curvature was not in the horizontal plane as unpredictable wind drift and unpredictable vertical impact would occur. If the barrel was in any plane other than the vertical, as the barrel heated and drooped, it would always droop at an angle which effect horizontal and vertical dispersion.

How much if any of this pertains to point blank BR, I don’t know.

Hovis
Click to expand...




Thanks Hovis. This is most interesting? :eek:

Invariably, when I come up with something like this on my own, I later discover someone else did this long ago. :rolleyes: Oh well,,,, I'll bet the military spent a lot more money on the project than I did; huh? :D

Later

Gene Beggs
 
Oh....here is a good one. Did you know its generally best if a groove is at 6 o'clock. Not better than the curve probably but there is a reason. Does anyone know.

Hovis
 
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