'Choke' at the muzzle of a barrel.

Has anyone experimented with swaging/clamping or otherwise forcibly reducing the diameter of the muzzle, in addition to the normal taper lapping? But only by a tenth (.0001") or two?

High performance air rifle barrels are manufactured in this manner. Both air rifles and .22 rimfires shoot 'dead metal' lead projectiles.

I know the recommendation for clamping muzzle devices is 'very light torque' on the bolts. What happens if the muzzle is restricted a bit? Does it harm accuracy?

Thanks for listening to the ramblings of a person that only wants to magically add accuracy to their barrel...
 
Just my thought ... Think about it like squishing a paper towel tube. Very hard to compress and keep concentric. You will slightly restrict the bore but also more than likely cause the end to be out of round, which is a worse problem.
 
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I was thinking about machining a sleeve, fairly thick-walled, with an I.D. of -.001" to -.002" smaller than the muzzle O.D.

Then heat up the sleeve and shrink it on the end of the barrel. This should provide even shrinkage at the muzzle. The amount of interference fit would have to be determined by experiment, both as to diameter and length of engagement. I would have to use a milling cutter and cut the sleeve if it needed to be removed. And then make another one, of course, to continue the experiment.

The experimental sleeve would include provision for attaching a normal tuner beyond the end of the sleeve.

Mr. Calfee, or anyone, have you ever tried anything like this experiment?

Thanks for listening.

--Mike Mc
 
I have thought about this myself, but don't have the equipment or expertise to facilitate the experiment myself. However, I'm anxiously waiting a report from someone that does.
 
As you know air rifle and rimfire barrels are very different beasts.
To say the least, hardness and external diameter, are the most striking ones being so apart.
External compression to form a "choke" on air rifle barrels is relatively simple and easy to be concentric. On a rimfire, harder and much more thicker walls, from my perspective, will pose more problems than solutions.
Of course, you can constrict a rimfire crown/choke area, but controlling that constriction and doing it concentric is beyond my knowledge.
Let's hear from the experts.
 
Putting choke in a RFBR barrel mechanically?

Friend Mike Mc:

Over my career I tried every method I could think of to induce choke into a RFBR barrel mechanically....

I was never successful.....

I will say this..... if you can figure a way to put a taper at the muzzle of a RFBR barrel mechanically, you'll make a fortune...


Your LBK and pistol fool friend, Bill Calfee
 
Putting choke in a RFBR barrel mechanically?

Friend Mike Mc:

Over my career I tried every method I could think of to induce choke into a RFBR barrel mechanically....

I was never successful.....

I will say this..... if you can figure a way to put a taper at the muzzle of a RFBR barrel mechanically, you'll make a fortune...


Your LBK and pistol fool friend, Bill Calfee
I kind of guessed you might have tried this already. Did you ever try shrinking a fairly heavy sleeve onto the muzzle? Just curious. If you have done this already, I will not bother thinking/worrying about this any longer.

Thank you for your reply above, Mr. Calfee. I appreciate it.

--Mike Mc
 
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Art Chochie of Time Precision used barrel fluting to induce taper in the bore.

He cut the flutes really deep starting at the chamber end and feathered them out as he got to the crown.

I don't know if or how well it worked but that is the way he explained it to me.

I do know some of Art's rifles did very well with his fluted barrels.

TKH
 
Art Chochie of Time Precision used barrel fluting to induce taper in the bore.

He cut the flutes really deep starting at the chamber end and feathered them out as he got to the crown.

I don't know if or how well it worked but that is the way he explained it to me.

I do know some of Art's rifles did very well with his fluted barrels.

TKH


Friend TKH:

Tony, I heard that the old Wilbur Harris web site, BRC, is up for sale...

You ought to buy it.....seriously....

You are by far the most popular poster on that site today.....and your knowledge of the subject of rimfire accuracy is unsurpassed.....

TKH, I'm most serious, you ought to buy that site...........

Think about is seriously...OK...

Your LBK and pistol fool friend, Bill Calfee
 
Friend TKH:

Tony, I heard that the old Wilbur Harris web site, BRC, is up for sale...

You ought to buy it.....seriously....

You are by far the most popular poster on that site today.....and your knowledge of the subject of rimfire accuracy is unsurpassed.....

TKH, I'm most serious, you ought to buy that site...........

Think about is seriously...OK...


Your LBK and pistol fool friend, Bill Calfee
I’m trying to find out the details.

Of course cost is one factor but what it takes to run it is another.

I would hate to see all the data on the site just disappear.!

I understand some of the info on the site is quite technical and beyond the comprehension of some.

But for those that can grasp the data it is a useable resource and quite a collection of historical information concerning precision Benchrest shooting as it has developed in this

country over the last 30 plus years.

TKH
 
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I’m trying to find out the details.

Of course cost is one factor but what it takes to run it is another.

I would hate to see all the data on the site just disappear.!

I understand some of the info on the site is quite technical and beyond the comprehension of some. But for those that can grasp the data it is a useable resource and quite a collection of historical information concerning precision Benchrest shooting as it has developed in this country over the last 30 plus years.
TKH
From February 2000 to the end of December 2021, I was a web programmer, with experience in computer programming, servers, databases, web services, software deployments and support.
Now, I am retired; have been since January 1 of 2022.
If you have questions about technical details you do not understand, I can probably help with either answers or perhaps refining questions to ask back.
I would not expect to spent a lot of time on it, but for the good of the shooting community, I can afford to spend some time helping, if there is a way for me to help.
And I would certainly understand if you do not want to get involved with me.
I do not expect anything in return and I am definitely *not* interested in any portion of the purchase.
--Mike Mc
 
I didnt find english word to this process how old gunsmiths here choke barrel muzzle tighter.Our language has word "krymppaus".

They put barrel to lathe and make about 20 mm lenght shoulder to barrel muzzle.Diameter 15,00 mm.Then they make bushing inside diameter 14,95-14,97 mm and lenght the same than barrel shoulder.
If I remember right this bushing walls thickness was little over than what is left barrel wall thickness when made 15,00 mm diameter shoulder.
-->22 LR barrel it is about 4,65 mm.

They put barrel to freezer or to dry ice.Then heated bushing "red" and put pushing on barrel muzzle.

Gunsmith Strömberg told me that he has done this to tens of barrels during his career and managet to get those alive.

And I know one 6 PPC guy whos gun lost accuracy and by slugging noticed that barrel muzzle is loose.He didnt cut barrel but made this "krymppaus" and he got barrel alive.

Mr Strömberg gave warning that prodect your eyes and face and everything when put hot bushing to cold barrel.

BR, Timo

Ps.
Dry ice is solid carbon dioxide. At its surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees Celsius), a frozen block of dry ice transforms directly into a gas, skipping the liquid phase entirely.
 
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From February 2000 to the end of December 2021, I was a web programmer, with experience in computer programming, servers, databases, web services, software deployments and support.
Now, I am retired; have been since January 1 of 2022.
If you have questions about technical details you do not understand, I can probably help with either answers or perhaps refining questions to ask back.
I would not expect to spent a lot of time on it, but for the good of the shooting community, I can afford to spend some time helping, if there is a way for me to help.
And I would certainly understand if you do not want to get involved with me.
I do not expect anything in return and I am definitely *not* interested in any portion of the purchase.
--Mike Mc
Mike,
Thank you so much for your offer to help. I’m not a computer guy so I don’t know what it takes to operate a site like this but I am making inquiries. I may need to pick your brain at a later date if that is ok with you.
TKH
 
I didnt find english word to this process how old gunsmiths here choke barrel muzzle tighter.Our language has word "krymppaus".

They put barrel to lathe and make about 20 mm lenght shoulder to barrel muzzle.Diameter 15,00 mm.Then they make bushing inside diameter 14,95-14,97 mm and lenght the same than barrel shoulder.
If I remember right this bushing walls thickness was little over than what is left barrel wall thickness when made 15,00 mm diameter shoulder.
-->22 LR barrel it is about 4,65 mm.

They put barrel to freezer or to dry ice.Then heated bushing "red" and put pushing on barrel muzzle.

Gunsmith Strömberg told me that he has done this to tens of barrels during his career and managet to get those alive.

And I know one 6 PPC guy whos gun lost accuracy and by slugging noticed that barrel muzzle is loose.He didnt cut barrel but made this "krymppaus" and he got barrel alive.

Mr Strömberg gave warning that prodect your eyes and face and everything when put hot bushing to cold barrel.

BR, Timo

Ps.
Dry ice is solid carbon dioxide. At its surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees Celsius), a frozen block of dry ice transforms directly into a gas, skipping the liquid phase entirely.
Thanks for sharing this information. Since many rimfire barrels are already straight, I think it might not be necessary to machine a shoulder on a barrel that is already straight. Also, unless the interference fit is more than .002", it might not be necessary to cool the barrel, at least not excessive cooling. I have heated many, many types of bushings in the past, for a shrink fit, and it is amazing how much a cylinder of steel will increase in inside diameter when heat is applied.
By my calculations 15.00 mm - 14.95 mm = .002 inches. That is not that much of a press fit. Heating a bushing will easily swell it more than .002".

I no longer own machine tools. I will need to find someone to help me with this project, if I decide to try it.

Thank you so, so much for this sharing of information. It is exactly what I was looking for to give me some idea that I am not completely crazy. Well, maybe only partly crazy...
 
Mike,
Thank you so much for your offer to help. I’m not a computer guy so I don’t know what it takes to operate a site like this but I am making inquiries. I may need to pick your brain at a later date if that is ok with you.
TKH
Pick away. There might not be much there to pick, but if I can help sort out some questions, I will be glad to help. You can PM me if you want, and we can always talk on the phone.
 
One question.
If you compress the bore, aren't you changing the twist rate at that point?
Pedro, that is a good thought. It might change the twist, slightly. Experiment will tell. I am after increased accuracy. If that does not happen, I would just remove the sleeve by machining it off.
 
I owe an apology...

My CYA accuracy fool friends:

This thread was started by MikeMcAllister about the possibility of inducing choke to a RFBR barrel mechanically.

I high jacked his thread with my comments about Tony Harper buying the BRC web site..

There's nothing worse on one of these Internet forums than for someone to butt in with a different subject....

But I did it....and me of all posters should have known better...

So I apologize for my stupidity....I will not let this happen again...

Your LBK and pistol fool friend, Bill Calfee
 
I owe an apology...

My CYA accuracy fool friends:

This thread was started by MikeMcAllister about the possibility of inducing choke to a RFBR barrel mechanically.

I high jacked his thread with my comments about Tony Harper buying the BRC web site..

There's nothing worse on one of these Internet forums than for someone to butt in with a different subject....

But I did it....and me of all posters should have known better...

So I apologize for my stupidity....I will not let this happen again...


Your LBK and pistol fool friend, Bill Calfee
Mr. Calfee,
No need to apologize. Human conversation is fragile and full of changes of subject. No harm done.
 
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