When you really step back and look at what is needed for barrel fitting, conventional lathes (like the 13×40's) are total overkill in both size and capability.
Good shootin' -Al
That is my opinion as well. It is very unfashionable nowadays to admit you do your barrel work between centers, the terms "dog and faceplate,steady rest, lathe centers, half point center" are never mentioned maybe banned....and I don't know why. Much ado and noise now about working thru the spindle hole with an outboard spider. A lot of truly great rifles were turned out in the heyday of custom rifles on nine or ten inch SB's, Atlas' or Logan's, early Jet imports, by nationally famous gunsmiths.
Last edited by flintlocke; 03/30/23.
Well this is a fine pickle we're in, should'a listened to Joe McCarthy and George Orwell I guess.
What we need for chambering and fitting is very simple.
-Short head stock -Short, rigid bed -1.5" spindle bore with very good bearings -Outboard spider -Inboard spider on a good face plate -Decent 3 jaw chuck -A good tool post
We don't need to be able to do 80 kinds of thread pitch, etc. Heck, it doesn't even need to be 220V. Short, simple and high quality is all we need.
My 14x40 has a 1.500+ spindle bore,but I do wish the headstock was narrower. First World "problems". Hint...............
Brad says: "Can't fault Rick for his pity letting you back on the fire... but pity it was and remains. Nothing more, nothing less. A sad little man in a sad little dream."
Your STUPIDITY never fhuqking ceases to amaze. Hint.
Fhuqking LAUGHING!..............
Brad says: "Can't fault Rick for his pity letting you back on the fire... but pity it was and remains. Nothing more, nothing less. A sad little man in a sad little dream."
You can indicate off the bore, or a pin in the bore. If the barrel is concentric, you can indicate off the outside. If your method includes dialing the throat area to zero, the runout at the muzzle is less important, as long as it is within reason. When I was working with a lathe which was too long in the headstock, I used sleeve which were slipped onto the barrel and which were a slip-fit into the spindle (3 1/2 inch). The barrel was indicated at the throat and centered at the muzzle by the sleeve. This worked out fine. Given the divergence seen in the average barrel, the alignment achieved this way wasn't any worse than indicating both ends. GD
You can indicate off the bore, or a pin in the bore. If the barrel is concentric, you can indicate off the outside. If your method includes dialing the throat area to zero, the runout at the muzzle is less important, as long as it is within reason. When I was working with a lathe which was too long in the headstock, I used sleeve which were slipped onto the barrel and which were a slip-fit into the spindle (3 1/2 inch). The barrel was indicated at the throat and centered at the muzzle by the sleeve. This worked out fine. Given the divergence seen in the average barrel, the alignment achieved this way wasn't any worse than indicating both ends. GD
OK Greydog, thanks, I was looking for a 'quick and dirty' setup to find the best center for longhole drilling for installing liners in old blackpowder barrels. So I guess a minus .0002 gage pin in each end of the bore should get me close enough. I am still old and hardheaded though, and work between centers when chambering, threading and crowning....grin, old dog old tricks.
Well this is a fine pickle we're in, should'a listened to Joe McCarthy and George Orwell I guess.
Centering buttons come in handy to center tooling on the cross slide and centering tailstock to the chuck. Caliber specific buttons can also be used to mount the barrel.
My understanding is that one big reason to go through the headstock is so that you can ensure that not only the mouth of the bore is concentric (to the chamber you are about to cut) but also that where the throat is going to be once the chamber is cut is concentric. Since the rifled bore can and does wander when they are drilling it that’s not a given. So, you may end up with the muzzle end of the barrel running “true” at the outboard spider or you may not; that’s not the goal. The goal is that the new chamber be running true to the bore at the chamber end of things.
To that end you could use gauge pins in the bore at the chamber end, or you can use a long-reach indicator to reach in and directly read the bore where the throat will be. That’s what I do. You are reading the lands/grooves so it’s kind of a pain. It’s a spendy little gauge. I’ll take a pic of it when I head back out there today.
This is why you use a spider chuck with rounded “jaws” (screws) rather than a 4-jaw: so the barrel can pivot on those round ends when you adjust at the outboard end. With the 4-jaw and its square jaws you could index in the bore (at the soon to be chamber mouth) there, but in terms of tilting the barrel to compensate for a wandering bore, such that the throat area ended up concentric, no. You’d be locked into whatever axial alignment the chuck jaws created.
It’s a very finicky setup and takes me a long time.
The headstock on my Webb is quite deep. I made extender sleeves that slip over the muzzle end of the barrel and lock on with brass screws. Works great.
At least some of what I typed above is mooted by at least some of the available floating reamer holders. You’d think a piloted reamer would also moot it, but things flex way more than folks usually imagine…
Maybe this will help visualize… I have a 7 SAUM donor rifle I bought recently and the plan is to make a 6.5 SAUM light rifle (not sure how light yet). I’m about to go on a 2-month wilderness backpacking trip (!) and for $$ reasons this isn’t gonna be the year for a new build. It occurred to me that I could rechamber the donor to 7 WSM, for which I have the reamer/gauges, and who knows, it’s at least possible it shoots great and then I have a toy to abuse for a while. I have mountains of 7 WSM brass, correct powders, etc. But here’s the catch. You know Big Green ain’t setting things up as above; so it’s possible, likely even, that the 7 SAUM chamber is not particularly concentric to the bore at the throat area. My new chamber is gonna follow that old one; the old one is the mutha of all pilot holes… and so my new chamber would end up also not concentric at the throat area. Course even given all THAT…… it might still shoot just fine.
Could you use a boring bar to make an existing chamber or throat more concentric before running in the finish reamer? I know this would be a delicate operation and my cross slide probably wouldn't handle it on my Sheldon , but a heavier duty lathe might do a clean job of this as long a you're only talking about a light pass on the non-concentric areas?
Never underestimate your ability to overestimate your ability.
Of course you can, and this technique is used by many. In fact, with the chamber bored true to start, the pilot on the reamer is superfluous. When rechambering a barrel in which the existing chamber is eccentric, you can bore the existing chamber and end up with a decent job. It will still be necessary to set back in order to correct an eccentric throat and neck. The barrel is indicated at the location of the new throat, then bored to true up the body of the chamber. It can be bored to match the body taper of the new cartridge, or it can be bored straight at about .010" under the shoulder diameter. Either way will give a straight start. I have used this method many times. GD
I watched a video of a guy fit and chamber a barrel without indicating anything. It was a 308. He tested it with factory Federal match ammo, and the first shots out of the barrel made a neat little cluster. Remembering (some of) how he did things I bet his chambering job was better than most factory rifles out there.
I watched a video of a guy fit and chamber a barrel without indicating anything. It was a 308.
He'll find employment with any number of pre-fit bubble packers. If he comes up with the idea of clear clam shell packaging and including a new case as a 'head space gauge', he'll get stock options and a better parking spot in the alley.
I had watched other videos of his in which he demonstrated the more modern and precise methods. He did the one I mentioned to demonstrate what could be accomplished simply using a steady rest.
I had watched other videos of his in which he demonstrated the more modern and precise methods. He did the one I mentioned to demonstrate what could be accomplished simply using a steady rest.
Ahhh...the rest of the story, as Paul Harvey would say.
Of course you can, and this technique is used by many. In fact, with the chamber bored true to start, the pilot on the reamer is superfluous. When rechambering a barrel in which the existing chamber is eccentric, you can bore the existing chamber and end up with a decent job. It will still be necessary to set back in order to correct an eccentric throat and neck. The barrel is indicated at the location of the new throat, then bored to true up the body of the chamber. It can be bored to match the body taper of the new cartridge, or it can be bored straight at about .010" under the shoulder diameter. Either way will give a straight start. I have used this method many times. GD
Just from putting quick calipers on 7 WSM and 7 SAUM cases (actually 6.5 SAUM) the 7 WSM reamer will clean up the chamber, but there’s not a ton of extra. If memory serves around .010” at the base of the case.
Should be a good “learner” if nothing else. And who knows, maybe the existing chamber is nice and concentric. Or close ‘nuff. If there’s anything machinists understand, it’s that nothing is perfect. There’s just “good enuff”, and that of course varies by the part or even a feature on a part and, of course, runs up against our ability to measure.
Could you use a boring bar to make an existing chamber or throat more concentric before running in the finish reamer? I know this would be a delicate operation and my cross slide probably wouldn't handle it on my Sheldon , but a heavier duty lathe might do a clean job of this as long a you're only talking about a light pass on the non-concentric areas?
Barrel blank in the headstock with Deltronic pins in either end. Indicate both ends. Drill and then reach in and indicate the throat. I use a solid carbide boring bar to taper bore to the shoulder. If you indicate the throat and taper bore it, it will be concentric to the bore. Your reamer will now follow the taper bored hole. I use no bushing as I do not want it to influence the direction of the reamer.
In my case (if that’s what we are talking about) it’s not a barrel blank; it’s a factory tube I’d be rechambering. So the problem, if there is one, is that the reamer will follow the pre-reamed hole a.k.a. the old chamber.
Of course you can, and this technique is used by many. In fact, with the chamber bored true to start, the pilot on the reamer is superfluous. When rechambering a barrel in which the existing chamber is eccentric, you can bore the existing chamber and end up with a decent job. It will still be necessary to set back in order to correct an eccentric throat and neck. The barrel is indicated at the location of the new throat, then bored to true up the body of the chamber. It can be bored to match the body taper of the new cartridge, or it can be bored straight at about .010" under the shoulder diameter. Either way will give a straight start. I have used this method many times. GD
Just from putting quick calipers on 7 WSM and 7 SAUM cases (actually 6.5 SAUM) the 7 WSM reamer will clean up the chamber, but there’s not a ton of extra. If memory serves around .010” at the base of the case.
Should be a good “learner” if nothing else. And who knows, maybe the existing chamber is nice and concentric. Or close ‘nuff. If there’s anything machinists understand, it’s that nothing is perfect. There’s just “good enuff”, and that of course varies by the part or even a feature on a part and, of course, runs up against our ability to measure.
This is the long-reach gauge I use.
.0005" indicator? Most that I know use a .0001" indicator. Run your indicator over a piece of .001" shim and tell me what your indicator reads.
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