Machining barrels for custom muzzle breaks

Seems like a lot of people want a muzzle break added to their rifles lately. I've been taking the actions off of the barrels so I can indicate both ends of the barrel in my lathe to get the most accurate class 3 threads possible for screwing on the break concentric to the bore.

Kind of takes a lot of effort on some rifles. Has any one got a system that works for them that might not be so labor intensive?

Any information folks might like to pass along concerning installation of muzzle breaks would be most welcome.

I do all barrel work on centers so I don't have to Mickey Mouse around dialing in barrels and it takes me about 1/2 to 1 hour to install a brake. It means you have to get some 60 degree center cutters or crowning reamers to retouch crowns after. I find that with extended centers, machines with 40 inch centers just barely cut it. If you don't have the bed length to do it you are sort of stuck working through the spindle. I think KDF used to sell a break installation kit way back when. You could call them and see if they still offer it. You have to run the centers in collets to get them to run close enough. I have seen guys do it in scroll chucks and 4 jaws but the run out at 8 inches is very poor. You can make good extended centers yourself from A2 or 01 if you have a tool post grinder. The machine I'm currently using is 45 inch centers and I do have problems with some 28 inch barrels.

A few points, Brownells sells these nifty brass covers for a live center if you do it via centers to protect the crown. I thought they were BS but they do work. You CAN indicate the barrel with the action still screwed to the barrel in your 4 jaw and center the muzzle. I recommend a recrowning to make sure it is good versus relying on what is handed to you. There are mandrels as well that fit your action. In the end, if you prefer thru the head stock it really isn't a big deal to break it down. If (as I have on some) want to keep it together while cutting the muzzle, it becomes tooling. Remember all the bad advice you got when you bought the lathe that said " the tooling is going to cost as much as that machine" . Let us know what you come up with

I too do mine from centers it low cost and most looking cost saving today

Dave

speerchucker30x3 said:

I do all barrel work on centers so I don't have to Mickey Mouse around dialing in barrels and it takes me about 1/2 to 1 hour to install a brake. It means you have to get some 60 degree center cutters or crowning reamers to retouch crowns after. I find that with extended centers, machines with 40 inch centers just barely cut it. If you don't have the bed length to do it you are sort of stuck working through the spindle. I think KDF used to sell a break installation kit way back when. You could call them and see if they still offer it. You have to run the centers in collets to get them to run close enough. I have seen guys do it in scroll chucks and 4 jaws but the run out at 8 inches is very poor. You can make good extended centers yourself from A2 or 01 if you have a tool post grinder. The machine I'm currently using is 45 inch centers and I do have problems with some 28 inch barrels.

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You just hadda bring up that tooling thingy didn't you keydiverfla? The new mill came in 2 weeks ago and I almost dropped a triple coiler steamer in my BVDs when I wrote the check for that. Now Grizzly wants $1,000 for a bisexual rotating table/dividing head, chuck and center. Jeff at Tools4cheap is going to get an order for $1,000 worth or R8 tooling at the end of the week. I need to buy material to make the steady rest for barrel fluting and a host of other gizmos. Plus a TIG to weld the new jigs and fixtures together to cut down machining costs which will be $1800 shot to pot. On top of that I have a Bridgeport E slotter that should be showing up soon to fit the back of the mill to cut action raceways which will save me buying a shaper. In two weeks I have spent over 1/4 the price of the machine on tooling. And then, hopefully, I guess, at the end of November it starts all over again with the new lathe. Are you sure I re-hired you keydiverfla?

have any of you experienced any problems with barrel stress at the muzzle after machining and threading the end?

Wounded Eagle said:

have any of you experienced any problems with barrel stress at the muzzle after machining and threading the end?

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I wouldn't know how to measure it even if I had. So I'm going to say, nupe.

speerchucker30x3 said:

You just hadda bring up that tooling thingy didn't you keydiverfla? Are you sure I re-hired you keydiverfla?

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Yes you did and you will never regret it : )

Wounded Eagle said:

have any of you experienced any problems with barrel stress at the muzzle after machining and threading the end?

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Yes, but it depends on whether you are dealing with Button-rifled, cut-rifled, or hammer forgerd barrels. Also, what thread size you are machining down to will also influence the results.

Generally, with cut rifled barrels the bore dimension under the muzzle thread will usually stay the same. On hammer forged barrels the bore will usually stay the same or tighten slightly. (actually a good thing!). BUT, be carefull with button rifled barrels as removal of too much metal when threading will often cause the bore dimensions to open up, due to the relieving of the hoop-stress that may still be in the barrel. This will adversely affect accuracy.

These effects are very easy to check for, either by bore slugging, or even checking with precision ground bore pilots in 0.0001" or 0.0002" intervals. I'm surprised that even a rookie like spear-chucker didn't know that or how to check for it. Especially seeing as he usually thinks he has an answer for everything, or what he can't do ain't worth doing, chambering/working between centers is the only way to go, blah blah blah.......

Best recommendations are to use the largest thread size possible for the given barrel diameter.

Kiwi 'smith Dean said:

Yes, but it depends on whether you are dealing with Button-rifled, cut-rifled, or hammer forgerd barrels. Also, what thread size you are machining down to will also influence the results.

Generally, with cut rifled barrels the bore dimension under the muzzle thread will usually stay the same. On hammer forged barrels the bore will usually stay the same or tighten slightly. (actually a good thing!). BUT, be carefull with button rifled barrels as removal of too much metal when threading will often cause the bore dimensions to open up, due to the relieving of the hoop-stress that may still be in the barrel. This will adversely affect accuracy.

These effects are very easy to check for, either by bore slugging, or even checking with precision ground bore pilots in 0.0001" or 0.0002" intervals. I'm surprised that even a rookie like spear-chucker didn't know that or how to check for it. Especially seeing as he usually thinks he has an answer for everything, or what he can't do ain't worth doing, chambering/working between centers is the only way to go, blah blah blah.......

Best recommendations are to use the largest thread size possible for the given barrel diameter.

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You just keep on making and cutting to those 0.0001 inch measurements Dean, you're an inspiration to us all. The machinists and tool and die makers in here could learn a thing or two from you.

speerchucker30x3 said:

You just keep on making and cutting to those 0.0001 inch measurements Dean, you're an inspiration to us all. The machinists and tool and die makers in here could learn a thing or two from you.

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??????? i didn't say anything about cutting to 0.0001" measurements at all, just measuring changes in the internal bore dimensions when you machine down the OD of the barrel at the muzzle.

But.... thanks for the compliment anyway Speelchucker, coming from you that really means alot.

You're my hero........!

SpeelChucker,
Sounds like you are getting what you need for tooling! The more tooling you have the easier the job. I recently got the company I work for to spend 20k on additional tooling for the CNC Mills so we aren't sharing 40 series holders. Trying to standardizing tooling amongst 4 CNC mills.

Rrdstarr said:

SpeelChucker,
Sounds like you are getting what you need for tooling! The more tooling you have the easier the job. I recently got the company I work for to spend 20k on additional tooling for the CNC Mills so we aren't sharing 40 series holders. Trying to standardizing tooling amongst 4 CNC mills.

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Well I suppose tooling is sort of a relative thing. Compared to some machine shops I have a lot of tooling, compared to hobbyists I'm nothing short of a tooling store. But compared to most full bore gunsmiths I'm average and at this point being a new shop again I'm probably a little light. I had a hiatus of about 6 years where I worked for another firm and in that time sold a lot of my tooling. Now that I'm back at it I'm in the works of tooling back up. The thing with gun work is that you are doing 100 different jobs that all require the same group of tools for each job. But you don't do the jobs in any order and each job takes an hour to setup and complete. In a machine shop the jobs are generally all different and you setup and work at the same job for several days or weeks. In a gunshop you seam to be forever setting up so anything you can do to minimize it saves you a lot of time and money. I start filling a caddy for each machine as tools are needed and when its full, I buy another and just park them at the machines. Some of the tooling is interchangeable but most is dedicated to individual machines. I generally buy as I need and can afford it. But I do recognize when tooling is needed and I do fill the need. And some times I just buy stuff because its neat and sparkly. Most of the tooling on those 2 caddys below are for that one machine.

speerchucker30x3 said:

.. It means you have to get some 60 degree center cutters or crowning reamers to retouch crowns after...

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How do you make that machining operation and ensure it's centred on the bore? Is this prep for having the crown on a centre while you cut the threads?

Grizzlypeg said:

How do you make that machining operation and ensure it's centred on the bore? Is this prep for having the crown on a centre while you cut the threads?

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Like everyone else. I use piloted center cutting reamers.

Thanks, that makes sense.

Yep, been doing it that way for 15 years or so too. I'm sure CST is still teaching it that way. Just keep some pressure back with the other end of the barrel on the tailstock center, especially when you wind the tailstock wheel back. The use of the ER collets is a nice method, though a good 3 or 4 jaw set to zero runout is fine too.

a differant alignment process

Bores are seldom straight, even in a match grade barrel. They air gage correctly, but that only measures ID. I learned to use a range rod in only the end I was going to use for chambering. That of course will work for both ends of the barrel. Still use a spider to support the receiver or muzzle end of the barrel sticking out of the head stock, but don't count on the spider for alignment. That is done all at the working end. Pacific Tool and Gage makes a very large aluminum pipe looking thing with 2 sets of 4 bolts (with copper ends) to chuck into your lathe. They call it an Action blue printing jig. ( half way down the page here Pacific Tool & Gauge, Inc. - Gunsmithing, Fixtures & Tooling ) I made my own after seeing their pictures. Those 8 bolts do great for aligning everything. On a bad day it can take a couple of hours to get to the 3 to 5 tenths run out on the range rod sometimes, but I know I am aligned with the bore in that section of the barrel. You do have to run the carriage or whatever you are going to attach your reamer/threading tool to back and forth a lot to make sure the bore aligns to what path the device you are using goes. My tailstock doesn't exactly align with my headstock's bore, but the carriage does. It is what I actual do all the work with. I don't use faceplates, dogs, centers,etc. Just the 3 jaw with that PT&G holder and the spider at the other end of the headstock to prevent the end from whipping.

This idea might be a bit different then what you usually hear. It works for me. Your experiencece doing it this way might be different, but should be worth a try.

Try it sometime when you have the time (and it does take time). Align both ends of the barrel with the lathe centerline, then try sliding your indicator along the length of your range rod and hand turn the chuck with the barrel attached to it. That indicator will wiggle as you move it along the length of the range rod, and sometime a scary amount. That will be the bend in the bore.

I got started on making my own match rifles. Indicating in the one end to eliminate/ignore the bend seemed to cut down a little on the quantity of tomato stakes I occasional got in. Many where shootable after setting the chamber back a little and using the one end to indicate off of.

Good luck,
Chris

I use the same method of alignment for for chambering and installing muzle brakes and suppresors. Suppressors are even more critical to alignment issues due to possible baffle strikes if not right.

There was a problem with this on some sniper rifles and it was traced back to working the barrel between centers. The threads and mounting surface were only coencentric with one point in the barrel, were the center ran.

I use two indicators at once on a range rod so that I dont have to move the carrage back and forth. Thinking of trying the grizzly rod method and seeing if it works any better.

The action jig also works for pistol barrels and short rifle barrels that are not long enough to fit thru the headstock.

You can chamber hunting rifles between centers and use a steady rest, but most good BR smiths use the thru headstock method.

Kiwi 'smith Dean said:

Yep, been doing it that way for 15 years or so too. I'm sure CST is still teaching it that way. Just keep some pressure back with the other end of the barrel on the tailstock center, especially when you wind the tailstock wheel back. The use of the ER collets is a nice method, though a good 3 or 4 jaw set to zero runout is fine too.

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A fellow Graduate of CST in 1989. I will get back to gunsmithing full time
when I retire in ten years!