View Full Version : A DIY-barrel-turn-down kit?

June 29, 2006, 09:01 AM
Is there such a thing as a ' DIY-barrel-turn-down kit'?
or a 'lathe alignment tool'? Similar to the thread aligner (example seen here:http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=22229&s=47995 ), but where you slide the caliber-sized rod down the barrel up to the wider part which is a known diameter: say 15mm in our case. Then instead of a threading die, a 'milling die' or a 'grinding die ': one designed simply to shave off metal down to the 15mm diameter we desire, is cranked down and turns down the barrel, keeping it even and true to the bore?

Or, is there any good, accurate way to turn down a barrel at home?

(FWIW: I am trying to turn down approx 1/2 of an inch near the muzzle of a barrel which tapers from about 16mm to 14mm, down to a uniform 14mm)

Thanks Experts!

June 29, 2006, 04:16 PM
I think what you are looking for is basically akin to an outside case neck turning tool, but instead designed for cutting steel. I do not know of one intended for that purpose. That said, I don't see a reason why a case neck turning tool with a custom bore-sized pilot couldn't do the job? It would be very slow going. I would look at the K&M tool, because it has a microadjustment system that would let you take down 0.0001" (.00254 mm) at a pass, which is what you will want to do. I don't know how far you want to cut back from the muzzle, so I don't know whether the throat or adjustment range of this tool will be deep enough? Call K&M and ask whether they think their tool could do what you want? (717) 292-3175.


June 29, 2006, 04:34 PM
Sounds like a worthwhile phone call to make!
Thanks again,

Mike in Michigan
June 30, 2006, 08:42 AM
Not sure if I correctly picture your need but here goes.
You want to turn down a 1/2" section of the muzzle to a certain OD for a short length.
About 30 years ago, I purchased a circle cutting tool at Sears that uses HSS 1/4" square lathe bits as the cutter. I used it to cut speaker holes in car doors back then. When correctly sharpened, it cut right through fabric, cardboard sheet metal and door stiffeners. I have seen similar tools in various catalogs over the years so I expect it is still made by someone. The tool has a 1/4" drill for the center pilot. The tool bit axis is aligned with the axis of the drill on the end of a radially adjustable arm. You could make a caliber-specific spud to replace the drill, isolate the end of the barrel with a stack of washers to protect the crown and turn the assembly by hand or with a very slow speed 1/2" drill. The bit would require some creative grinding to get the cutting edge lined up but is quite doable.
Basically, it is simply a very rigid variation of a set of trammel points and beam with one point as center and the other as cutter.

June 30, 2006, 11:04 AM
Find someone with a lath and turn it down correctly.
messing up the crown on a barrel is a minor annoyance to fix, but messing up the rifling at the crown is repaired by cutting the barel down.

Harry Bonar
July 1, 2006, 08:58 PM
Dear Sir:
If you are truing to turn the bbl. to THREAD MAJOR DIAMETER you won't do it with a tool that indexes in the muzzle without ruining the rifling in the muzzle.
I wouldn't put a spud in my rifles muzzle.
Now, if your muzzle is already at major thread dia. then this tool will work to get your die started straight - possibly. I know of no hand held tool that would locate in the muzzle that would have the stability to do this. (to turn metal off of 0.d.)! As Nick says you're wanting a "neck-turning" type tool to reduce the muzzle to Major thread dia. so you can die thread it.
There is only one way to do this. In a lathe - and you'll need to strip it to get it through the headstock in a lathe. You will have to pull the bbl. (hard) and either get it through the headstock with the rear zero'ed - or catch the chamber end in a chuck and use a steady-rest to gain acces to the muzzle. Then you have the problem of concentricity of o.d. to i.d.
You would be better to catch the chamber end in a chuck and use a live center to accurately turn to major thread diameter. Then you must also clean up that crown where the live center has run! Then you still have the alignment problem and threading - all braked must bear on a shoulder! Do not tighten over tight or you'll stretch the I.D. of bbl. near the bullet exit.
As you can see, if that tool would work it would be great but I fear it wouldn't!
Dear Sir:
I would not try to pull this bbl. either on the Siminov or AK. I don't care for muzzle brakes unless put on al the factory of origin for combat use only.
Bullet wipe, alignment, hole size - all these thing mitigate against brakes unless installed in the armory or point of mfg!
Sorry - Harry B.

July 2, 2006, 12:10 PM

I thought perhaps he might be trying to turn his barrel down for a front sight? I got that idea because of his mention of the narrower 14 mm portion to the muzzle beyond where he wants to cut (unless this is a reverse taper?). I did a Palma style front sight on my dad's Savage. The design slipped on over a smooth O.D. and red Loctite was applied when zeroing it at the range to establish the final position. I did dad's rifle on my lathe, but a polished pilot like those on the hand crowning tools Brownells sells should do no more than lightly burnish lands. Alignment for a target sight is less critical than on something the bullet passes through since the sights are adjustable.

My concern is more about whether the barrel is stress-relieved|? You can get slug-detectable bore enlargement when you cut down the contour of a barrel that hasn't been stress relieved, though 1 mm out of 16 mm isn't going to do a lot. In the case of dad's rifle, we planned to lap it's bore anyway. We saved that step until all other barrel work was done, and in that way any sins were corrected by the lapping. Cpileri may want to consider adding this step?


July 2, 2006, 12:31 PM
Simply be reading your answers. Even all the info that may not be immediately applicablee to the problem at hand is being stored away for later.
Thanks for being so forthcoming and complete!

About bore lapping: does anyone make a kit to bore lap for someone who doesn't reload for the required caliber? I see Brownell's loads some 22 rimfire impregnated with lapping compound. But others are loose projectiles.
Can it be done by hand? by a relative amateur?

July 2, 2006, 02:57 PM
For fire-lapping rather than hand lapping, look at the 4th item down here (http://www.neconos.com/shop/?shop=1&cat=20&cart=47135). Not cheap in centerfire, if they have your chambering listed. You can get Lee Anniversary kit and a set of dies and start reloading for not much more.


Harry Bonar
July 2, 2006, 06:47 PM
Hey! Nick:
I just love your Freudian saying at the end of your post.
Respect your advice.
Harry B.