I am wanting to cut a few chambers. My lathe is too long to put a spider at the back end, so I will have one end in the chuck, an i will be using the steady. I am thinking of making a threaded sleeve of known length that will ptotrude a bit past the back of the go, no go gauges so I can measure how much more to cut, with out spinning the action back on. I have a good selection of measuring and indicating tools. I want to cut the tenon and the chamber withoit removing the barrel from the lathe. Thanks.
Feel free to tell me I am overthinking this.
- Thread starter 22to45
- Start date
Depending on the action but you should be able to do it all and thread the action on to check headspace and fit... the threads should be cut "loose' enough so there is no friction screwing the action all the way on (loose threads - 60degree - are better than tight) ... allow about 2 thou for 'crush'.
I don't know anything about lathes.
I know that the guy on Ultimate Reloader channel, when he chambers barrels, he talks about making a barrel extension that threads onto the muzzle threads, to make the barrel long enough to be captured on both ends by the lathe chucks.
https://rumble.com/v3o1k81-7prcw-build-part-1-woox-titano-chassis-and-barrel-chambering.html
10m54s he talks about it and shows it
I know that the guy on Ultimate Reloader channel, when he chambers barrels, he talks about making a barrel extension that threads onto the muzzle threads, to make the barrel long enough to be captured on both ends by the lathe chucks.
https://rumble.com/v3o1k81-7prcw-build-part-1-woox-titano-chassis-and-barrel-chambering.html
10m54s he talks about it and shows it
22-45, If you're going to use the spindle on the tail stock to center your barrel while you thread the tenon and hold the shim wrapped muzzle end in the jaws, that will give you a very true to axis of bore threaded area. The spindle will keep it all under control as long as the bearings in it are decent.
You can also set up the barrel between centers and turn it with a dog leg via the face plate.
If you want to go the route of using a steady rest that will work but is much more tedious to set up.
Before you cut the tenon diameter, you should check the "center" of your bore to the outside circumference of the barrel itself while the bore is mounted on the live center at the tail stock.
Usually, pre-profiled barrels have already had their outside circumferences trued to the axis of the bore by the manufacturer but if you're profiling a "blank" barrel as well, then you need to handle that properly before cutting your chamber.
It's pretty easy to set up a dial gauge to check for true.
It may require a light cut to "true up" the outside circumference to be identical to the center of the bore. This can all be cleaned up easily.
It's not uncommon for a bore not to be true to center of outside circumference, especially with some of the lower end manufacturers.
That's a big mistake made by people when they set their spiders to the outside circumference. It should be set to a spud in the bore.
When you've cut your tenon threads then you can put a ''spud" in the bore and set up the chamber area in your four jaw chuck so that the bore is as close to center as you can get it. Then you can profile the face of the chamber area, ala Remington or whatever, before starting to cut your chamber.
You want to use a floating reamer holder for the job, not hold it tightly in a chuck at the tail stock.
Chuck up the floating reamer holder instead and when you start cutting your chamber, as long as you have a tight fitting pilot the reamer will cut true and clean.
If you hold the reamer tight in a chuck or even try to push it in using the live center in the dimple on the end of the reamer, you could end up with an untrue to the axis of the bore chamber.
The floating reamer holder eliminates this issue.
You can also set up the barrel between centers and turn it with a dog leg via the face plate.
If you want to go the route of using a steady rest that will work but is much more tedious to set up.
Before you cut the tenon diameter, you should check the "center" of your bore to the outside circumference of the barrel itself while the bore is mounted on the live center at the tail stock.
Usually, pre-profiled barrels have already had their outside circumferences trued to the axis of the bore by the manufacturer but if you're profiling a "blank" barrel as well, then you need to handle that properly before cutting your chamber.
It's pretty easy to set up a dial gauge to check for true.
It may require a light cut to "true up" the outside circumference to be identical to the center of the bore. This can all be cleaned up easily.
It's not uncommon for a bore not to be true to center of outside circumference, especially with some of the lower end manufacturers.
That's a big mistake made by people when they set their spiders to the outside circumference. It should be set to a spud in the bore.
When you've cut your tenon threads then you can put a ''spud" in the bore and set up the chamber area in your four jaw chuck so that the bore is as close to center as you can get it. Then you can profile the face of the chamber area, ala Remington or whatever, before starting to cut your chamber.
You want to use a floating reamer holder for the job, not hold it tightly in a chuck at the tail stock.
Chuck up the floating reamer holder instead and when you start cutting your chamber, as long as you have a tight fitting pilot the reamer will cut true and clean.
If you hold the reamer tight in a chuck or even try to push it in using the live center in the dimple on the end of the reamer, you could end up with an untrue to the axis of the bore chamber.
The floating reamer holder eliminates this issue.
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Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
Some of the best chambering techniques have been compiled in a pdf by accurateshooter.com.
I think you can find it on there by searching "chambering", or I could email it to you if you PM me.
I think you can find it on there by searching "chambering", or I could email it to you if you PM me.
- Location
- Western Manitoba
Perhaps oddly, I have never understood that thing about "crush" - assume that I have determined that I want 1.000" from rear end of barrel to the barrel shoulder - do I set that up to try to cut to 1.002" or to 0.998" to get .002" "crush"?
I have two Mauser 98 barrels I have been dithering to do - from the Kuhnhausen Shop Manual, appears that a Mauser 98 barrel is supposed to seat on BOTH the barrel shoulder and on that inner "C" bulkhead, although I do not think I have found that to be the case on many Mausers that I have "unscrewed" - so it may or may not be "important" for them.
In other words, when "torqued up" do the male threads on the barrel get shorter, or do the female threads in the receiver get longer - or other way around?
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Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
The male threads stretch a little, the female threads compress a little, and both the receiver face and the tenon shoulder compress a little. Considering the difference in surface area, it is safe to say that most of the deforming occurs at the shoulder/receiver interface, and considering how tight some barrels are, "crush" is a very appropriate term.
So you would cut it at .998", but the dimension you would be working with would be the headspace dimension, not the barrel tenon length dimension. Barrel tenon length is not a very critical dimension.
So you would cut it at .998", but the dimension you would be working with would be the headspace dimension, not the barrel tenon length dimension. Barrel tenon length is not a very critical dimension.
On an action where the barrel is shouldered on the front of a receiver... If you hand tighten a chambered barrel as tight as you can with your two hands... and you can barely feel the bolt close on a go gauge, when you tighten the barrel more with an action wrench and a barrel vise you will not be able to close the bolt on a go gauge... 2 thou, maybe 3 thou difference. The barrel screws in deeper.
- Location
- Western Manitoba
Probably demonstrating my lack of experience at this - one barrel is already chambered for 7x57 - so I was measuring with a 7x57 GO gauge in that - to figure where barrel shoulder and rear of barrel should end up in another "random" receiver and bolt - when barrel is turned hand tight into that receiver, I can close that bolt on the GO gauge, with a .030" shim on the bolt face - so has to be "set back". So if I peel from the barrel shoulder, I will run into rear of barrel on that internal "C" bulkhead - so needs peeling done at BOTH places - but you are correct - the measuring starts from the GO gauge protrusion. The other barrel was a CNC made thing that was deliberately "long chambered" in 257 Roberts - same GO gauge, but apparently I have to peel away some from BOTH rear of that barrel and from that barrel's shoulder. I do not own chambering reamers for either 7x57 nor for .257 Roberts - have to work with what showed up, I guess - if even possible.
Go and No Go gauges are great if you're chambering a lot of rifles, but for the average home smith they're a very expensive option.
Far cheaper to take an unfired factory round, dump the powder and use the case face along with some "plasti-gauge" to set headspace.
I like the headspace to be tight, no more than .002. Not all people like it that way, but that's just my personal preference.
Guntech's description of his method is an easy one to follow and works very well.
Far cheaper to take an unfired factory round, dump the powder and use the case face along with some "plasti-gauge" to set headspace.
I like the headspace to be tight, no more than .002. Not all people like it that way, but that's just my personal preference.
Guntech's description of his method is an easy one to follow and works very well.
You don't need a no go gauge for precise chambering... only the go gauge... and the gauge you buy for "whatever" today you can sell for the same "whatever" in a few years...
As far as using a factory round as a go gauge... I have seen differences of several thousands of an inch in the same box of factory ammo... so which case should you use... they are all made smaller to fit in a minimum chamber.
Buy one go gauge and do it right.
When I had occasion to chamber some barrels on a largish lathe ( 20x120), I made up a sleeve which was just a push fit into the spindle bore to center up the muzzle end of the barrel. The breech end was held in the four jaw and dialed in as usual. This worked out fine. The barrels were for my rifles and I was able to win stuff with them, so I considered it a success!
When I started out, it was SOP to set the barrel up between centers for threading and set up in the steady for chambering. I did a bunch of barrels this way, and I'm sure Dennis did too. FWIW, I always fit mausers to contact the receiver face .002" before they contact the inner ring. The barrel easily turns past contact to hit the inner collar. Once it is contacting the inner ring, it won't turn much more.
When I started out, it was SOP to set the barrel up between centers for threading and set up in the steady for chambering. I did a bunch of barrels this way, and I'm sure Dennis did too. FWIW, I always fit mausers to contact the receiver face .002" before they contact the inner ring. The barrel easily turns past contact to hit the inner collar. Once it is contacting the inner ring, it won't turn much more.
Yes Bill for many, many, many years it was all between centers for threading and set up in the steady for chambering... until I got my 11 inch Rockwell. It was standard procedure taught at gunsmithing school in 66/67. Probably because pretty well any lathe can be successfully used that way... I always did my Mausers the same way too... a slight crush on the receiver face kept the bluing salts from creeping out as well...
I agree with what you're saying 100% but for one offs ?????????????????????/
