It is an AR barrel. Two sections to turn - before and after the gas block seat. Makes it easier to do than a continuous tapered barrel. Do the turning half and half. Hold the gas block area in the 4 jaw chuck. Dial it in. Support the muzzle end on the live center. Turn down as desired. Reverse. Repeat, turning down the breech end. Gas block to muzzle can be parallel. Breech end might be multi diameter, tapered in sections. There is always less than a foot from chuck to live center. Likelihood of warping or springing or chatter is very low. Go easy, take your time. Shorten as desired, thread for brake, crown. There is then the opportunity to bore a good brake to be coaxial with the bore.
Turning Material Off of a Heavy Barrel
- Thread starter mmattockx
- Start date
16" in length.
I want to turn it down to something like a medium heavy profile from the extra heavy, not looking for pencil weight at all.
Not at all concerned about surface finish after. A light finishing pass with a new carbide insert would be more than adequate for me. Maybe bead blast it after that light pass and that would be more than good enough.
That is my hope as well.
Since it's already less than 18" that option is not available to me, unfortunately. Legally, anyways...
Thanks for all the replies.
Mark
There may not be any red seal gunsmiths but there is redneck gunsmiths. I've turned.I stepped barrel in 8x57 on a drill press, by pressing two files together on both sides of the barrel at the same time to avoide going out of round. And it shoots as good or better than it did before. It was a fun thing to try. But I would not do it on anything of any value.I'd suggest a lathe, but you are welcome to try a hand file.
I have contoured and re-contoured hundreds of barrels. I have fluted and octagoned a few dozen. To reduce weight, I prefer turning. Since I am not an actual certified gunsmith and only have my fifty years of experience as a qualification, my input may mean nothing. On the flip side, I have NEVER turned a barrel for an AR, and don't plan to!
fingers284
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Im not sure who would "certify" him in Canada, maybe a mail order home course of some kind but other than that the "Licensed & registered " part of the equation simply means he jumped thru the hoops of the fire arms branch for insurance and safe storage warning devises....not a thing to do with actual firearms fixing or building acuity.
Get him to show you his "certification" and who he is "registered" with. There is no certification nor registration body for gunsmiths in Canada. His license will be a Firearm Business License, which any business can get and does not require any gunsmithing experience or education.
FWIW I have a Firearm Business License too.
LOL, NOBODY walks away from a CNC machine, not if you want to avoid destroying the machine.
Not really. A live centre in the muzzle guarantees turning on centre (given the operator can get the other end straight in the chuck).
That is an interesting idea. I've never chucked an AR barrel on the gas block surface. I have a collet chuck and that would be perfect for a .750" gas block surface.
Turning a heavy barrel in a lathe to reduce weight will work fine if the barrel was correctly stress relieved to start with. Trial and error... If not properly stress relieved it will end up like a crank shaft.
To be a gunsmith in Canada requires you purchase a federal license for $100. It requires no knowledge of guns what ever. There is no certification required. Some "licensed" smiths can produce other documentation of training they may have had, but it is not a requirement for licensing.
To be a gunsmith in Canada requires you purchase a federal license for $100. It requires no knowledge of guns what ever. There is no certification required. Some "licensed" smiths can produce other documentation of training they may have had, but it is not a requirement for licensing.
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This and Emory cloth for this technique used to be extremely common. Not best practice, but it definitely works.I suppose this falls into the category of, "if it works, it's not stupid."
You got lucky. As often as not this is the opposite of what happens with those barrels.
The steps were part of the processing to keep them consistently accurate with a variety of loads and it works very well.
I've got a few of those barrels in my "scrap bin" and I use them for projects such as bedding pillars or whatever else they might be useful for.
AR barrels need to be treated differently than other profiles, as tiriaq described.
I will admit, the one job I dislike when building a rifle is "profiling" a barrel from a "Blank"
I have an old but well maintained Chinese knock off lathe, but without a taper attachment.
So, to do the job properly, because not all blanks are drilled or hammer forged true, I start the process by turning the ends between centers before starting to cut the profile I want.
The biggest mistake made turning down blanks is cutting TOO MUCH with each pass. You can take a bit more if you have a flowing coolant system to keep the cutting tool cool, as well as the material you're cutting. I don't have a flowing coolant system, because I seldom have the need for one, and they're messy. That's why most CNC machines have enclosures.
I do have a flowing coolant system on my milling machine, but again, only use it if needed.
Tiriaq mentioned something very important, "making sure everything is centered to the axis of the bore is crucial."
HEAT is your worst enemy when profiling a barrel blank to the desired form.
Finish was mentioned, but that's up to the operator. The finish can be anything wanted, from rough tooling marks to nearly what appears to be a polished finish, waiting for the different grades of emory cloth to do the final polishing. Some people have access to bead/sand blasting units to make a "matte" finish.
The HEAT created during cutting is much more than many think, especially if the cuts are too deep and being turned too fast.
My method of profiling a barrel is SLOW at the very least. HEAT creates distortion, which can't be removed. Heat causes expansion, between the holding points. This can cause the barrel to "warp" and end up off center in the middle. I've seen this on more than one barrel I've repurposed.
The AR barrels, because of the much different profiles can also create other issues I haven't mentioned, but I'm willing to bet, HEAT is also something to deal with.
These days, I no longer even attempt profiling a barrel, I buy them profiled.
Guntech mentions proper stress relieving. Stress relieving a barrel blank. Most smiths don't have the proper equipment to do this and the blanks they buy are already heat treated or even cryogenically treated. The thing is, as soon as that barrel's shape is altered, it can create stresses which will have a negative effect. PO Ackly mentions that, in much more detail in his writings. But I agree completely with heat treating being critical.
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Me too. So much so I'd never do it. Buying a pre-profiled blank is the way to go.
I agree. I would much prefer buying a contoured blank to starting with a cylindrical blank and profiling it myself.
Years ago I did a good sized batch of 36" muzzleloader barrels - started with .58 cal. 36 1/4" long blanks 1 3/16" in diameter - finished tapered octagon, tapered round. IIRC, took about 2 1/2 hours apiece. Machined them using a South Bend 16x57 lathe. Round portions were done in two stages, a steady rest being used. Had two spring on me, warping as steel was turned off. They ended up as shorter, lighter octagon to round barrels.
The OP was asking about recontouring a 16" Shilen heavy AR carbine barrel. That really is a different kettle of fish. It is a quality finished barrel. Breech is done, gas block journal finished, no doubt muzzle threaded. Really short sections would have to be turned down. The method I described above would work. One AR competition barrel I slimmed down lost about a quarter minute in grouping ability - but I don't know if that was because of the machining on the barrel or because the rifle was now much lighter and handier and perhaps not as steady to hold. There are variables.
Years ago I did a good sized batch of 36" muzzleloader barrels - started with .58 cal. 36 1/4" long blanks 1 3/16" in diameter - finished tapered octagon, tapered round. IIRC, took about 2 1/2 hours apiece. Machined them using a South Bend 16x57 lathe. Round portions were done in two stages, a steady rest being used. Had two spring on me, warping as steel was turned off. They ended up as shorter, lighter octagon to round barrels.
The OP was asking about recontouring a 16" Shilen heavy AR carbine barrel. That really is a different kettle of fish. It is a quality finished barrel. Breech is done, gas block journal finished, no doubt muzzle threaded. Really short sections would have to be turned down. The method I described above would work. One AR competition barrel I slimmed down lost about a quarter minute in grouping ability - but I don't know if that was because of the machining on the barrel or because the rifle was now much lighter and handier and perhaps not as steady to hold. There are variables.
Is this the RCMP licensing ~ https://www.rcmp-grc.gc.ca/dam-gan/hq-dg/pdf/firearms-armes-a-feu/forms-formulaires/5486e.pdf or something different? (I've been half assed looking at it forever)
My Lawyer keeps telling me I need to get it, but there is nothing in the activities that pertain to antiques .... any other activities are covered under my provincial license.
What does the $100 "gunsmith"option (and probably required $100 storage option) allow you to do that people without the license are not allowed to do. That is to say (ask) what indemnification does the gunsmith activity provide you with?
While I don't cut as many from a full blank anymore, I re-contour a good percentage of all the barrels I fit. Usually just because the barrelmaker doesn't produce the contour I want. Also, some barrel makers are set up to profile barrels well while others are not.
Removing material never induces stresses, unless the tool is dull. Stresses within the material are removed with the material; this is what causes the material to warp. Cryogenic treatment does little is anything to relieve stress within the steel, though it may aid in machinability. Stress relief, or normalizing is done with heat.
I was once involved in the manufacture of some bars which were about 5ft long, two and a half inches by an inch and three fourths thick, and trapezoid in cross section. The material was flame cut plate, two inch. When machining, it would warp like hell. I stress relieved the material by putting it into an 8 inch pipe, 6 ft long, covered in sand. I heated it with a tiger torch until it was beginning to glow nicely, then covered the ends of the pipe with sand and left it overnight. No more warpage and machining was easily done.
By the way, when I turn a barrel, I like to take as heavy a cut as I can and feed it as fast as I can. Tool profile is the most critical factor. If the tool cuts without too much chip pressure, it won't induce as much heat. As the barrel heats from turning, you have to back off on the tailstock. One can buy a spring loaded center which will allow for work-piece elongation, but I've never used one.
Removing material never induces stresses, unless the tool is dull. Stresses within the material are removed with the material; this is what causes the material to warp. Cryogenic treatment does little is anything to relieve stress within the steel, though it may aid in machinability. Stress relief, or normalizing is done with heat.
I was once involved in the manufacture of some bars which were about 5ft long, two and a half inches by an inch and three fourths thick, and trapezoid in cross section. The material was flame cut plate, two inch. When machining, it would warp like hell. I stress relieved the material by putting it into an 8 inch pipe, 6 ft long, covered in sand. I heated it with a tiger torch until it was beginning to glow nicely, then covered the ends of the pipe with sand and left it overnight. No more warpage and machining was easily done.
By the way, when I turn a barrel, I like to take as heavy a cut as I can and feed it as fast as I can. Tool profile is the most critical factor. If the tool cuts without too much chip pressure, it won't induce as much heat. As the barrel heats from turning, you have to back off on the tailstock. One can buy a spring loaded center which will allow for work-piece elongation, but I've never used one.
Not "checking" you here - but which law? I cannot find reference ... criminal code? firearms act? some other hunk of legislation?
I agree working on flintlocks and antiques is dancing the file edge ... but technically "not guns"
