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starik
01-23-2008, 05:08 AM
I wonder if an aluminum tube which tightend to the muzzle can effect the inside diameter of the muzzle? If the answer is yes, then I would be able to conrol the choke of the muzzle with increasing the torque. Also , in 2013 action can the torque at the breech can effect the chamber diameter? How strong should be the tourque on the screws at the breech?
Guy.

Kathy
01-23-2008, 09:44 AM
Friend Starik:

You've asked a very interesting couple of questions.....

Friend Doug, who posts on this forum, started a web site for me.....I have not decided whether or not to use it.........but in case I do I have been making a list of subjects to write about......things that I probably wouldn't put in Precision Shooting Magazine......

I am going to put your fine questions on my list.......I'm sure there are other folks on this forum that will be glad to give you some answers until that time.

http://billcalfee.org

Your friend, Bill Calfee

gordon gauge
01-23-2008, 11:56 AM
Quite a while ago this very thing was discussed at length, don't know if a search would bring it up.

It went something like this,

Bill posted that one should be careful and not overtighten the muzzle tuner as you could cause too much choke or constriction i.e.: reduce the inside diameter of the barrel.

A guy from L.A. who had been attending our matches for some time was a machinest (sp) and gunsmith who read Mr. Calfees post and tried it out himself and was not able to measure any difference. So he clamped it (the muzzle) into some part of his lathe and cranked it down tight, putting many times the force that you could get from the aluminum collar of the tuner and still could not measure any difference in the inside diameter.

This went back and forth and folks got angry and unkind things were said.

Bill was using another person to post for him, and I ended up as messenger boy for the guy with the lathe. This further complicated the discussion.

In the end, Bill said that the best way to confirm the fact was to slug the barrel without the tuner, and then mount the tuner and crank it down tight, then slug the barrel again and you could feel the bore get tight where the tuner collar was.

And that's where it ended, I think.

Kent Owens
01-23-2008, 02:09 PM
I think Bill was correct, and it takes slugging it to find out the difference. If you have a barrel that is very uniform in dimension, from one end to the other and hardly no choke at all, or no choke, you can feel the difference when slugging it after torqueing a tuner up tight. I know this because I have a barrel like that I've been playing with, and I've done it. However if you have a barrel with 4-5 tenths of choke in it, it's hard for me to tell the difference when slugging it, because of the choke, even though the tuner is probably constricting it a bit.

As far as trying to control choke with a sleeve tightened at the muzzle, I'd doubt it because I'd guess the barrel might possibly put into an out of round state, then it might not? Depends on luck! It'd be a simple experiment to try it and see how it worked.

pacecil
01-23-2008, 02:11 PM
This question should have been put to any engineer, or for that matter any second year engineering student. Any sleeve, of any material, put on the barrel, at muzzle or breech, with interference fit, or with collar clamped with screws, WILL CAUSE THE BORE TO CONSTRICT. There is no question of this, the only question is how much. The sleeve, or collar, will exert a pressure between it and the outside diameter of the barrel. This pressure even if it were only 1 psi will cause the bore to move in to a smaller diameter. High interference fits or tightly clamped collars produce pressure of several hundred to several 1000 psi. This bring bores in from a few .0001" to several .001". Larger ratios of outside diameter to inside diameter will allow the bore to move in to a lesser degree.

gonefishing
01-23-2008, 03:41 PM
How tight should the screws clamping the tuner to the barrel be?

bugs
01-23-2008, 03:53 PM
Gonefishing,
I have heard just tight enough so it's doesn't fall off and stay put.
Eddie

gordon gauge
01-23-2008, 04:13 PM
This question should have been put to any engineer, or for that matter any second year engineering student. Any sleeve, of any material, put on the barrel, at muzzle or breech, with interference fit, or with collar clamped with screws, WILL CAUSE THE BORE TO CONSTRICT. There is no question of this, the only question is how much. The sleeve, or collar, will exert a pressure between it and the outside diameter of the barrel. This pressure even if it were only 1 psi will cause the bore to move in to a smaller diameter. High interference fits or tightly clamped collars produce pressure of several hundred to several 1000 psi. This bring bores in from a few .0001" to several .001". Larger ratios of outside diameter to inside diameter will allow the bore to move in to a lesser degree.


The question was put to an engineer with a Masters degree from Stanford who works for Ferrari on their race team (his initials are on the conrods of their F1 car). He said that in theory there could be constriction or decreasing interior demensions but at that level the fact that steel is not stable and the molecules are actually moving around that measurement would probably not be possible.

So as Bill said and Kent seconded, it is something that has to be felt, and then only in certain situations. I think.

gordon gauge
01-23-2008, 04:19 PM
How about cutting slots inside the collar and putting rubber O-rings in them and then just tightening until the collar bottoms the orings?

Rich In Kansas
01-23-2008, 04:21 PM
This was discussed a long time ago, maybe 5 or 6 years ago. I had a barrel in 2000 that was pretty good. I could feel the constriction using a bullet as a slug. A longer slug may not feel in. I experimented an found for that particular barrel I could not feel 9 inch pounds but could feel anything higher. I have used 9 inch pounds on all my barrels since then and have not had a tuner fall off. Rich

billyg
01-23-2008, 04:23 PM
Not being an second year student I have some questions>
If the constricting collar is Al and not a steel of same alloy and hardness as barrel and not the same ratio of barrel diameter to bore would not the softer and thinner clamping material stretch in a differing ratio to the compression of the barrel material?
And if screws are used to force compression of collar what stress and stretch is involved here? Also would not the modus of compression act in all dimensions of length as well dimensions of diameter?
And what about the lack of memory of ferrous metals-once compression occurs what amount of it will not return fter compression relaxed?
I am confused.

Fred J
01-23-2008, 04:43 PM
I asked this same question of Doug Shilen back in 2000. His answer, was you can't change the inside diamentions of a 22RF, using the present style tuners. His reasoning, was you would strip the Aluminum clamp before you reached sufficent torque to cause any changes. That was good enpugh for me.

hoser
01-23-2008, 05:04 PM
The rubber O-ring deal won't work because the tuner needs to be firmly attached to the end of the barrel to cancel the barrel vibrations.

I have a very long tuner on a prone rifle (11" long), and I didn't want to clamp and epoxy it on the barrel before I found the "right position" for the front sight, so I just silicone glued it on. I never could get it to "tune" until I finally clamped and epoxied it, and then it really made a difference.

Hose

college
01-23-2008, 07:24 PM
I am NOT an engineer. But I do not understand how the soft aluminium collar can constrict the steel of a barrel. Logic tells me that the aluminium collar would stretch rather than have the barrel constrict.
College

gordon gauge
01-23-2008, 08:32 PM
Yep, it's a real poser. Gonna give ya wrinkles on your forehead if you pose on it too long. http://emoticons4u.com/crazy/1088.gif

Řyvind
01-24-2008, 05:20 AM
Hey Guy (s) :-)

I have tried this with variuos results on the torque from barrel to barrel. The groups gets better and when overdoing they open up again. In my experience the best results with my barrels are between 4 to 6 Nm torque. I have two screws on the clamp and they are torqued differently as a rule. Also by clamping flush or maybe a little to the rear of muzzle the group pattern changes. You just have to try it.

Tom C.
01-24-2008, 11:20 AM
i read this and wondered aren't you supposed to have some
choke in the muzzle end of your barrel can you build it in by
tightening something down on it if so is it controllable and
is it permanent? if you take the tube off does the barrel open
back up? if you had a barrel that needed some choke could
you build it in from the outside?

Tom C.
01-25-2008, 10:10 AM
if i might have put my tuner on too tight.
if so can i redo it, or ?

Fred J
01-25-2008, 10:34 AM
Tom:
You can loosen and retorque to no more that 20 inch pounds. If you had it fitted properly, that's more than enough. You don't want to damage the treads of the tuner.

BigMacky
01-25-2008, 11:50 AM
Hey Guy (s) :-)

I have tried this with variuos results on the torque from barrel to barrel. The groups gets better and when overdoing they open up again. In my experience the best results with my barrels are between 4 to 6 Nm torque. I have two screws on the clamp and they are torqued differently as a rule. Also by clamping flush or maybe a little to the rear of muzzle the group pattern changes. You just have to try it.

Hi Řyvind ... Got a question ... does Nm mean Newton Meters? If so, does 4 to 6 Nm equate to like 35 to 53 inch pounds?

Fred

Tom C.
01-25-2008, 12:07 PM
i gave lynwood h. the measurements
and he reamed it for me seemed to just
barely slide on then i tightened but not
with torque wrench i was wondering if i
could just loosen the screws and retighten
with a torque wrench? would i have already
stretched the clamp?

Fred J
01-25-2008, 02:28 PM
If the tuner was bored to a snug fit, you won't have sprung the clamp. You would have stripped the threads in the aluminum first. Like I said, with a close ( snug ) fit, 15to 20 in pounds will be sufficent.

Tom C.
01-25-2008, 03:48 PM
i wouldn't have asked but it seems like everytime
i do anything with guns anymore i find there's a
new or different way to do it. so now i ask and wait
a couple of days and see what i probably almost did
wrong this time. thanks.

gordon gauge
01-25-2008, 05:15 PM
Off topic but I'll be quick.

Where are you guys getting your torque wrenches. TIA

hoser
01-25-2008, 05:43 PM
I got my Anschutz torque wrench from a fellow on E-Bay for $45 new in the slip-tube. I think Anschutz re-packages the Gehmann wrench.

Hose

DonMatzeder
01-25-2008, 05:51 PM
Harbor Freight sells a cheap one. Seems to be pretty consistent though and every one that I have seen on the line has been just like mine.

Fred J
01-25-2008, 08:12 PM
Strudivant makes a great one. And only $120 buck.

fishin'fever
01-25-2008, 08:13 PM
Why not make a pin to a close fit to bore dia,sliding fit. Than install the collar and tighten,any reduction in bore dia and pin will not move or slide tension will change. Just an idea,hope it helps!

gordon gauge
01-26-2008, 02:53 PM
Thanks gentlemen for the torque wrench info.:)

Jetmugg
01-28-2008, 01:25 PM
Young's Modulus (the modulus of elasticity) for steel is approximately 29 x 10 to the 6th power Pounds per Square Inch. (I don't know how to use superscripts in this formatting). This is largely independent of the actual composition of the steel or the degree of tempering.

This value is the slope of the stress-strain curve for steel in the elastic range. (i.e. if you let go of the stress, the steel will return to it's original shape). Strain is unitless, so the slope of this curve is expressed as P.S.I. Young's modulus allows you to calculate how much stress is required to move a material a given distance. It is essentially a measure of "stiffness"

The steel barrell is elastic. It can be stretched or constricted as much as you might like (until it fails catastrophically) by tha application of an external force.

All you need to do is figure out how much you want to constrict the bore, and then you can calculate how much stress is required to apply. You could use an aluminum sleeve, a steel sleeve, or any other suitable engineering material to apply the needed force to the outside of the barrel.

In case anyone was wondering, I'm a Metallurgical Engineer by trade, and a shooter by hobby. Although I'm primarily involved in Smallbore Silhouette Shooting, I enjoy the benchrest forums due to the ultimate emphasis on accuracy.

SteveM.

Tom C.
01-28-2008, 05:46 PM
ok another question answered.
999 to go.

gordon gauge
01-29-2008, 12:18 AM
That just makes more questions.

How much torque can we apply to the aluminum collar on our muzzle end tuners without constricting the barrel? Or the steel collar of a mid barrel tuner? The quotes out of your text book were very impressive, and seemed to make sense to me, but now you gotta apply that to our situation and come up with some numbers we can use.

Don't have a gun with a tuner? Tell us where you are and the closest one will bring one over so you can make the measurements.

Thanks a bunch for posting this good info, and I (and I'm sure many others on this forum) look forward intently for your findings in this matter. :)

Jetmugg
01-29-2008, 08:41 AM
If the question is "How much torque can we apply without constricting the barrel" - the answer is "NONE".

Any amount of applied force will change the dimensions of the barrel. You may not be able to measure the amount of constriction, but rest assured, it has changed with the application of an external force. The difference may not be detectable with a micrometer or by "feel", but the amount of constriction is directly proportional to the amount of external force applied.

The only way to have absolutely no constriction or distortion of the barrel is to have absolutely no force applied.

SteveM.

Pokerplayer
01-29-2008, 09:34 AM
I have been playing with "out of the box" ideas on and off for ten years. I had an action set up to check barrel length to consistant velocity. I have an old ansch barrel I have ben using at this time It is now 8" and was frozen then a stainless ring shrunk to it, then set up with bloop tube (to protrctect scope) The bbl would shoot in the low .2 @ 16" long I have not been able to get there yet but the ammo is a lot more consistsant over the chrono. I believe the rest is my deviation @ this point as it does not ride as well as th longer bbl. I am positive you can choke a bbl