Barrel indexing; is it worth it?

B.Johnson

Do you relise how deep a 4 start thread whould be? think about the thread on your scope objective, or eye piece.
 
B.Johnson said:
Do you relise how deep a 4 start thread whould be? think about the thread on your scope objective, or eye piece.
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Bob, it would not take long for me to tell you everything I know about machine work. The four start thread sounded good when it was mentioned but I think I can see why it wouldn't work unless the action threads were the same.

The first time I ever heard of a multi-start thread was when Don Nielson showed me a speed screw he made that used a three start thread.

I know I have a lot to learn but this is how I learn; by doing. I need all the help I can get.

Later,

Gene Beggs
 
Multiple Lead Threads

I hasve cut quite a few multiple lead threads, and, as a skilled machinist, I would not look forward to applying this to a action and tenon.........jackie
 
Okay,,, back to square one. :eek:

This the first time I can remember when my first attempt at anything proved to be the best solution after all. Sometimes you just get lucky; huh? :)

Until something better comes along, I'll continue testing with the differentially threaded bushing; I know it works and is quick and easy to adjust.

I believe the best advice thus far comes from Jerry Stiller and Jackie Schmidt and that is, opening up the receiver threads from 1.062 to 1.125. This will give plenty of room for the bushing and leave the barrel tenon pretty close to original size. And I'm sure it will be best to make the bushing from a harder, tougher material then 416 stainless.

Onward thru the fog! :cool:

Gene Beggs
 
I wouldnt worry

much about the bushing getting too thin, look at a helicoil. That is thin and then some. Also, 416 will work as well as anything. The weakest part of the thread is all you have to meet. The only reason to use something else is from a galling issue. Dont use 17-4.
 
Gene Beggs said:
Okay,,, back to square one. :eek:

This the first time I can remember when my first attempt at anything proved to be the best solution after all. Sometimes you just get lucky; huh? :)

Until something better comes along, I'll continue testing with the differentially threaded bushing; I know it works and is quick and easy to adjust.

I believe the best advice thus far comes from Jerry Stiller and Jackie Schmidt and that is, opening up the receiver threads from 1.062 to 1.125. This will give plenty of room for the bushing and leave the barrel tenon pretty close to original size. And I'm sure it will be best to make the bushing from a harder, tougher material then 416 stainless.

Onward thru the fog! :cool:

Gene Beggs
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I disagree. If your .940 diameter tennon is working without hard bolt lift than that is all that you need for the present cartridges that you are shooting.

Now, if you decide to try some larger cartridges with more powder capacity and/or larger case diameters than consider openning the action diameter thread.

Why alter an actions threads if not needed?..................Don
 
stiller said:
much about the bushing getting too thin, look at a helicoil. That is thin and then some. Also, 416 will work as well as anything. The weakest part of the thread is all you have to meet. The only reason to use something else is from a galling issue. Dont use 17-4.
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Thank you Jerry, I don't know how many times I have thought of how similar this bushing is to a helicoil. No one ever questions the strength and integrity of helicoils.

Gene Beggs
 
If I was looking to pick-up strength in a threaded bushing. I would go to a ground thread over a cut thread.
 
If one bought a steel action that was 1.5" in diameter, he could have the threads opened sufficiently to allow a bushing and keep a 1.062 tenon. The best way to ensure good barrel shoulder to action face contact, with this setup, would be to use a thick precision ground washer in the position of a Remington recoil lug. Gene's method of holding the bushing from the back seems to be good. One advantage of the bushing would be for fitting barrels to a glued in action. The bushing could be used to check thread fit on the lathe. Also, if one wanted to reduce the action's weight, it could be turned down to 1.360" behind the front receiver ring.
 
Boyd Allen said:
If one bought a steel action that was 1.5" in diameter, he could have the threads opened sufficiently to allow a bushing and keep a 1.062 tenon. The best way to ensure good barrel shoulder to action face contact, with this setup, would be to use a thick precision ground washer in the position of a Remington recoil lug. Gene's method of holding the bushing from the back seems to be good. One advantage of the bushing would be for fitting barrels to a glued in action. The bushing could be used to check thread fit on the lathe. Also, if one wanted to reduce the action's weight, it could be turned down to 1.360" behind the front receiver ring.
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Boyd,

All excellent suggestions! :D

Gene Beggs
 
Strength of the threads is not the problem here. The only problem you have is with the thread fit. You are trying to get good contact at all the thread mating surfaces. You need this to insure you get the added stiffness that the bushing and receiver can give to the tenon. You want this whole assembly to act like a shrink fit cylinder where the outer cylinders are pressed against, and supporting, the inner cylinder. Whether the threads are rolled , cut, or ground is important only if it makes them engage closely. You want each thread to be in tight engagement and you will probably achieve this only by torquing to a high level. In normal tolerance threads only a few threads have high contact loading. Any thing you can do to make the loading very high, and distributed evenly over all threads, would be a step in the right direction.
 
Big Al

That is not a ground thread. That is a formed thread, where the metal is actually displaced by either an internal extruding tap, or rolled by a set of ID rollers on the shank of a bolt. The vast majority of bolts are now produced this way, even the cheap ones. Most production nuts still use the cutting method.

A ground thread is actually a thread that has it's final dimensions, (usually on a hardenned piece), formed by grinding. A good example is the spindle threads inside your Micrometer.

Intenal threads are much more difficult to form in thinner sections, as the metal will simply expand rather than subject to the thread being formed.

For this application, I would amagine rolled threads would not be very cost affective. Forming inside threads is a simple matter of purchasing a extrusion tap. We use them on occasion at my shop. But the equipment involved in external thread rolling is very expensive, and is justified by the quantity of parts made........jackie
 
Paceil

You make a good point. Most of us strive to keep everything within "tenths" when chambering and performing the other machining operations on barrels, introducing another component does complicate the issue.

Of course, if the deferential nut is machined all on one set-up, and the threads are fit to the standards that is the norm in this type of work, there should not be any problems.

I still say that there are a multitude of Benchrest Gunsmiths out there who are saying, "you gotta be sh-tting me". Right now, when we hit the tune, these things shoot at a level that is mind boggling. I guarrantee that the general attitude among many top Gunsmiths and Shooters is, "this just ain't worth it. Learn to tune a Rifle, and read the wind".

I get to talk to these shooters at matches, and stuff such as this, in their opinion, is borderline ridiculous. It makes for good conversation on Forums such as this, but that very conversation is often permiated by shooters who have never stared over a set of windflags at a Match. ......jackie
 
Let me see...one shooter gives another a barrel that he thinks is only good for fire forming, and when it is indexed in one particular position it shoots very well, but in no other position. Naa, I've never seen it or done it, must be BS. Besides, everyone is always satisfied with their barrels, and even if they aren't, they all have plenty of money to keep trying barrels till they get a good one....right;) Besides, the best shooter are always the best designers, and come up with all the new ideas.

Right now, Gene is at the very beginning of something that may turn out to be major (or not). By having a public discussion and hopefully getting others involved in experiments of their own, data of these successes or failures will accumulate much faster, and we will be able to have confidence in our conclusions much sooner. Let's just let it cook for a while, and see what happens.

I seem to remember a lot of negativity about tuners a while back, in fact most still don't have any use for them . I guess that that means that they don't work. (You know I'm kidding here.)
 
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jackie schmidt said:
I get to talk to these shooters at matches, and stuff such as this, in their opinion, is borderline ridiculous. It makes for good conversation on Forums such as this, but that very conversation is often permiated by shooters who have never stared over a set of windflags at a Match. ......jackie
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I've spent time with racers in quite a few different venues and there's ALWAYS a preponderance of guys who scoff at this sort of thing.

I can think of several reasons why which are not related to advancement of the sport!

:)

Maybe this is why Jim Borden is my gunsmith of choice. Whether Jim joins in to the discussion, agrees or disagrees, he rarely just discounts stuff out of hand. I appreciate folks like him who spend time forming opinions on the stuff being talked about in the community.

Folks like Jim.....

Or Stiller

Or Butch

Or Mickey

Or you.........or many others who frequent this board are responsible for all sorts of advances in the shooting sports.

I'm not really swayed by the opinions of guys who're setting out on the river fishing along with everyone else, I want to know the guy who catches the MOST fish in any given circumstance not the guy who got lucky that day. I want to know the guy who comes up with the new fishing lure based on watching the folks around him. This board has been responsible for HUGE changes over the last 10-12yrs.... I like to use the 6BR as an example. When I joined this board back in about '96 it was ridiculed by these same guys. The 18" twist thirties were equally ridiculed...... EVERYBODY followed Bruce Baers lead in the long-range game. EVERYBODY was shooting Euber style 68's in SR BR. EVERYBODY knew that full-length resizing was silly. EVERYBODY that was on the inside just knew that ....blah...blahh...blahhh....... well you get my drift.


Scoff away all. I say that ANYTHING which promotes a healthy interest in the shooting sports is good. :) Hey, maybe some day some of us silly non-shooters will step up to the plate.



al
 
Gene,

Someone here earlier suggested using the arrangement used on an AR with the flanged barrel. Since this is not a gas gun, you can index anywhere you want, with less trouble than you're going through now I should think.

Years ago when I considered something like this, I wondered how to attach the barrel and index it but not loose strength radialy by making some loose fitting "socket" for the barrel to ride in. I never built an arrangement like that and the barrel nut arrangements I did see didn't shoot for squat. That's not to say it didn't have merit, but there were certainly trade offs in the designs people used that were way too much error in one place to make up for any gain in the indexing process.

The one idea I would probably have tried which I don't see talked about here, was to use an arrangement something like the keepers on the top of a small block chevy valve. If you remember the old tapered locking gizmos that hold the valve springs down. With something like that but with maybe several groove/boss arrangements, it might end up something like a breech on the guns of big ships. Of course, there'd be a nut to pull on the barrel and keep it all tight. Maybe with the barrel then sitting inside a smooth taper, there would be no loss of radial strength during high pressure, and the cross sectional area of the keepers would be small enough that it would not take away from the strength of the action.

Design of something like that might be easier than the twinsert idea, and it might be more difficult. Then again, there is the issue that comes up from time to time where you "drop a valve". Anyone who's done that knows its not good, so it would pay to make a good solid arrangement.
 
4Mesh said:
Gene,

Someone here earlier suggested using the arrangement used on an AR with the flanged barrel. Since this is not a gas gun, you can index anywhere you want, with less trouble than you're going through now I should think.

Years ago when I considered something like this, I wondered how to attach the barrel and index it but not loose strength radialy by making some loose fitting "socket" for the barrel to ride in. I never built an arrangement like that and the barrel nut arrangements I did see didn't shoot for squat. That's not to say it didn't have merit, but there were certainly trade offs in the designs people used that were way too much error in one place to make up for any gain in the indexing process.

The one idea I would probably have tried which I don't see talked about here, was to use an arrangement something like the keepers on the top of a small block chevy valve. If you remember the old tapered locking gizmos that hold the valve springs down. With something like that but with maybe several groove/boss arrangements, it might end up something like a breech on the guns of big ships. Of course, there'd be a nut to pull on the barrel and keep it all tight. Maybe with the barrel then sitting inside a smooth taper, there would be no loss of radial strength during high pressure, and the cross sectional area of the keepers would be small enough that it would not take away from the strength of the action.

Design of something like that might be easier than the twinsert idea, and it might be more difficult. Then again, there is the issue that comes up from time to time where you "drop a valve". Anyone who's done that knows its not good, so it would pay to make a good solid arrangement.
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4Mesh, the valve keeper arranagement you mention is something I considered. I also thought about a row of ball bearings with half the groove in the tenon and the other half in the receiver. The balls could be inserted thru a hole drilled in the receiver and the hole filled with a set screw once the balls were in place. The joint would be tightened with a Savage type barrel nut.

I'm sure this would work. Whether it would be an improvement over what I'm using now is anyone's guess. One thing for sure, it would require a completely new action, while the bushing arrangement I'm now using can be installed in most any action with a 1.062 diameter thread.

I'm always open to suggestion.

Later,

Gene Beggs
 
Ok, since we're sharing crazy ideas.... :rolleyes: I'll share one of mine.

Bear with me :D

Once we've accepted the idea of ANOTHER JOINT of some sort, or another method of fixation....... Howsabout replacing barrels at the neck instead of reaming an entire chamber? KEEP that perfect chamber and just pop on a fresh barrel with a new neck and throat. IF the concept could be proven to work then actions could be made which accept a sleeved chamber, or for that matter an action could be made with the chamber reamed right into the receiver ring which brings us back to one joint.

I'd love to be able to inspect my throat/leade by just looking at it.

I've thought about the sealing issue, I believe that it can be resolved. One of my resolutions includes differential threads like a K&M neckturner which produces incredibly high tension at a vertical joint (and could include indexing now that Gene's brought it to our attention)......... In fact, this is why I bought my lathe. Not for the indexing, I hadn't thought of that, but for exploring the different method of barrel attachment. Unfortunately it's gonna' take 50-100hrs of my limited time just to get the lathe run in, right now it ain't gonna happen for a while.

Hey, I'm just throwing the idea out before the crowd since the crowd IS gathered around nicely.... :)

flame away


al
 
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