Barrel Choking

[Taso1000]

I was interested in putting a choke on a B51 barrel and in my research I found this post:

http://www.gatewaytoairguns.org/GTA/index.php?topic=43105.40

In reply #40, Whitefang mentions a cable crimp tool that can be tightened with a torque wrench.  I have not been able to find something that matches his description but I found a hydraulic cable crimp tool.  Can this be used to choke barrels?

They are right around $40 but all the changeable dies I have seen are hex shaped.  Do any dies exist that are round?  I guess you could drill out and split a nut to use inside one of the existing hex dies.

Would something like this work or are there better diy options out there? 

Thank you all in advance.   

Taso

[rsterne]

The best setup I have seen is a large pipe cutter with the cutting disc replaced by a third ball bearing.... As you tighten the tool, the three bearings press harder on the barrel, and you rotate the tool around the muzzle to collapse it.... You can check the bore with pin gauges and stop when you get the right amount of choke.... I haven't done it, but I understand it is pretty easy to control the amount of choke, and the fact you are rotating the "die" (bearings) around the barrel makes it even....

Bob

[Taso1000]

Bob,

Thank you for your input, I appreciate it.    

I was trying to figure out how to apply the force on the hydraulic ram consistently and repeatedly.  I haven't yet.  Maybe a hydraulic fluid pressure gauge could be installed somehow depending on the unit. 

I was thinking rotating the barrel 120 degrees, or less, each time and compressing to make it even all the way around but that is still not as even as the rollers on the pipe cutter.

I was hesitant on a pipe cutter because in reply #33 Whitefang said the rollers were digging into the barrel versus rolling and I would still need to buy a heavy duty pipe cutter and figure out how to replace the cutter.

I have a light duty pipe cutter but I don't think it would be strong enough to choke the barrel even if I could figure out how to replace the cutter with a roller or ball bearing.

I don't have a problem farming out the choke labor but I figured if I was going to choke 6 or more 1/2" barrels shipping will start to add up. 

I enjoy learning how to do stuff by myself.  Most of my posts are about me tinkering with new things lol  If I can't do it, then I can't do it.   

Taso

[Taso1000]

Bob,

You were right.  After more research, thinking it through and my lack of tools I looked into the big pipe cutters on Ebay.  I found a Ridgid 202 in great condition for $42 shipped. 

When you said ball bearing I only though like a bb not an actual bearing.  Sorry.  Once I get the cutter could you help me find a bearing or maybe a third roller?

Then Taso's barrel choking business will be open!  Just kidding Administrators.   

Thanks,

Taso

[SpiralGroove]

Hey Bob,
Do you think putting the barrel end (1") in a lathe chuck and tightening it very hard could work too?
Kirk

[rsterne]

I don't think so.... more likely to break the chuck, IMO....

Bob

[Taso1000]

Bob,

So I would use the pin gauges like "go" and "no go" gauges?  Can you recommend what sizes to start with for .177 as I don't have any pin gauges. 

How much choke do you recommend?  .001" from what the grooves currently are or choke down to a certain size to be kinda pellet universal lol?

Thank you,

Taso

[nced]

I was interested in putting a choke on a B51 barrel and in my research I found this post:

http://www.gatewaytoairguns.org/GTA/index.php?topic=43105.40

In reply #40, Whitefang mentions a cable crimp tool that can be tightened with a torque wrench.  I have not been able to find something that matches his description but I found a hydraulic cable crimp tool.  Can this be used to choke barrels?

They are right around $40 but all the changeable dies I have seen are hex shaped.  Do any dies exist that are round?  I guess you could drill out and split a nut to use inside one of the existing hex dies.

Would something like this work or are there better diy options out there? 

Thank you all in advance.   

Taso

I've choked a R1 barrels that was chopped for use with my R9 and it was successful. I used two methods when testing the choking procedures and I first used a heavy pipe cutter bought from a Cummins Truckload sale truck and replaced the cutter wheel with a home turned steel roller to swage the muzzle after cutting off the factory sight grooves and choke. While it did create a choke it also messed up the bluing on the muzzle.........
Uploaded at Snapagogo.com
Uploaded at Snapagogo.com

After cutting off the messed up choke, facing and re-crowning the barrel, I used a home made "clamp block" from the head of a 1"-8 hex bolt  (has a head 1 1/2" across the flats). After cutting off the bolt shank I chucked the head in my lathe and faced both front and then back. Next step was to bore the bolt head and lap the hole so it was .005 larger than the od of the R1 muzzle. Next step was to radius the lapped hole edges and then split the bolt head across the corners with a hack saw, then smooth up and sharp edges from the hack saw cut. The muzzle of the barrel was then placed in the bored hole in the "clamp block" and tightened in my HEAVY 5" vise! The way I gaged the progress of the choking procedure for each method was to push new pellets through the bore till the smallest restriction was at the muzzle. Using the clamp block and vise method required EXTREME PRESSURE on the vise handle and, toward the end of the swaging I had to add a piece of pipe to the handle to get the restriction. After noticing a slight restriction at the muzzle I rotated the barrel 90 degrees in the clamp block and constricted the muzzle till I felt just a tad more restriction to the new pellet being pushed through the bore.......then I called it quits. There was indeed a noticeable choke at the muzzle when I finished but it wasn't as tight as the factory HW choke. A couple pics......
Uploaded at Snapagogo.com
Uploaded at Snapagogo.com
Uploaded at Snapagogo.com 

Here is a target I shot at 50 yards "from bucket and sticks" using that home chopped and choked R1 barrel on my R9..........
Uploaded at Snapagogo.com
I shot group #1 aiming at the bull where I shot group #2 and was so pleased with the group that I took the time to zero the gun at 50 yards and proceeded to shoot the second group.
 

[Taso1000]

Ed,

I had considered using your bolt die idea in the hydraulic cable crimper.  Unfortunately I don't have the tools to make a die like yours.  I do have a vise but it's a "warehouse" special so I doubt it's very strong.

With the pipe cutter all I need is another roller and I should be good to go.  I hope.   

I am lucky that all my guns' muzzled are cover by breaks, ldc's and sights.  So any marring from the rollers will be hidden. I'm just hoping I don't have a soft barrel where the rollers will dig in.  Hopefully I can go slow enough not to create a speedbump. 

Thank you,

Taso

[Taso1000]

Hi All,

So I received my Ridgid pipe cutter.  It is model 202 with the wide rollers.  I have attached pictures.  Can anyone help me with a roller to replace the cutting wheel?  The width of the cutting wheel axle? is .7435 inches.  And the axle diameter is .346.  I am not sure what the max roller diameter can be?  Does any one have any suggestions or know if a narrow model roller will fit in the cutter position?

Thank you,

Taso

[nced]

"I am not sure what the max roller diameter can be?"
When I made my "roller swager" from a Cummins Truckload Sale pipe cutter set I simply machined a roller to replace the cutting wheel to fit. In my case a piece of O1 tool steel was machined to the same width as the "cutter roller" and the diameter was the same as the cutter diameter.

IMHO, simply match the cutting wheel if possible and keep in mind that the wider the flat surface of the fabricated roller the more pressure will be needed to effect the constriction. Actually, only about 1/2" of the muzzle needs to be constricted to affect a choke.

[Taso1000]

Ed,

Thanks for the help. I don't have access to machine tools or have any friends that do.  Unfortunately.  If I did I would be dangerous.     In a good way.

There is a version of my pipe cutter that has narrower rollers opposite the cutter.  These "seem" to be the same width as the cutter.  The cutter is the same on the regular and wide pipe cutter. 

I was looking online for dimensions of replacement rollers but no dimensions are listed.  I guess I could order them and trim or shim them. 

Thanks,

Taso

[real7]

Taso, I saw your response to my post on this subject, thanks for directing me here.
Is it possible that one of your rollers would fit in the position of the cutter ? If it will then you just need a replacement roller.

[Taso1000]

No.  My cutter is the wide roller model.  The cutter side seems to be the same as the regular roller cutter.  There are two different part numbers for regular and wide roller.  I was curious if the regular roller would fit on the cutter side.  I can't find any dimensions for the rollers.  Either the regular roller fits or it doesn't.  I could trim or shim the width.  But if it's too big in diameter it may not fit and roll.

I am new to huge pipe cutters.  I guess I can order the narrower rollers and find out.  If they can't be made to work I cn return them.  I was wondering if also getting new wide rollers for the other side to minimize the barrel marring.

Taso

[Taso1000]

I ordered and just received the narrower roller for the regular width pipe cutter.  While it fits perfect width wise it's diameter is too large.

So now I have a dilemma. I think I may be able to get the roller fixed in my drill press with a bolt and nut with rubber washers for friction to keep it from spinning. 

I think this way I can bevel the edges so that it will clear the pipe cutter head?  Or I would need someone to turn the whole diameter down to fit. 

If I bevel the edge the three roller ends will be more offset.  If I turn down the diameter I will have the smallest offset but I may not have the reach.

Or I can try to clearance the cutter head with a rotary tool and some sand drums to clear the roller as is?  This would be the easiest for me to do and maybe the best solution.  Do you think the tool will weaken or because the force is in the opposite direction it will not make any difference?

What do you guys suggest?

Thank you,

Taso

[rsterne]

I think I would grind or turn a bevel on the edges of the roller until it drops into the casting and you can get the pin in place.... ASSUMING of course you know that there is clearance at the back of the hole for that diameter, in enough width to do the job intended....

Bob

[Taso1000]

So I tried to clearance the edges of the roller to fit in the cutter head.  All I accomplished was to make it shinier lol.  I guess it's too hard for my tools to cut.

I didn't put those dings in the roller.  I uncovered them lol

Taso

[Taso1000]

I just remembered I have an old bench grinder.  I'm going to see if that will work on the edges.

Taso

[rsterne]

Just grind a bevel on the edges.... keeping it 100 straight isn't critical, just eyeballing it will do.... as long as it fits in the hole....The working surface will simply be a bit narrower....

Bob

[Taso1000]

Bevel grinding was a success with the bench grinder and a drill going the opposite direction.  I'll post some pictures when I get the pipe cutter back together.

Now my question what should I lubricate the rollers with?  I have Super Lube, Ultimox and Loctite moly paste.  I think I read moly is for high pressure applications.

Thanks,

Taso