TO all,

I am just getting started and have been experimenting and researching different set-ups used when chambering barrels.

Lookin gthrough the older manuals it seems that the preferred method back then was to use a live center to get teh barrel true and then support the barrel in the thread area with the steady rest and chamber that way.

More recent text says to chuck the breech end in the chuck, extending the barrel though the spindle bore and out the rear of the bore, then use some type of simplt work support mounted in the back of the bore to center the muzzle end of the barre.

Here is my question, when I found the lathe I though would do everything I wanted, I decided on a Jet 14x40ZX with the big 3 1/4" spimdle bore. I chose this machine because I will be doing 50 BMG work where barrels are often 36 inches long and sometimes over 2.5" in diameter.

This machine is a big gear head machine and the spindle bore length is quite long. I coulduse a rear spindle support if the barrel is 30 inches or longer but for conventional barrel lengths, they will not reach though the bore.

IS using the steady rest to support the breech end an accurate system or is it out dated?

Will this technique produce results that would result in extreme range accuracy. Most of the rifles I will make will be for extreme range varminting and target work.

What are your opinions on teh prefered work set up. Also will the steady rest provide an accurate enough hold to do extreme accuracy work?

Thank for the opinions!

Good Shooting!!!

50

I always use a steady rest instead of holding the future chamber in the chuck jaws. I have heard that you may cut an out of round chamber because of the pressure of the jaws on the chamber section while cutting the chamber. When the jaw pressure is released the chamber section may spring out of round. Never wanted to possibly ruin a good barrel blank to test this theory. Any input welcome.

Fiftydriver,

Absolutely! The degree of accuracy you obtain, will depend on how accurately you set up the job and how well you are at machining. It is much faster to run the barrel in the chuck, using less steps, however, exceptional results are easily obtained if you are forced to go between centers.

I prefer to use the chuck whenever possible, however there are times when it is necessary to do the work between centers. When that happens, this is the usual sequence I follow when performing this work.

1. Set my compound feed to 30 degrees, mount a dead center in the chuck and using the compound feed, true the center, leaving it in place in the chuck.

2. Next, align and true my tail stock's "live" center with the one I just trued which is still in the chuck. The centers should now be absiolutely true.

3. I will now mount the barrel between these centers, placing the muzzle end at the tail stock, and turn approximately the last inch of the muzzle end true. This end piece is usually excess and is used in the chuck to drive the barrel for the remaining work.

4. Next place this machined end in the chuck, and place the tail stock's live center in the breech end of the barrel and then dial in the muzzle end in the chuck. The bore should now be running dead true to the center of the machine.

5. From here, the first thing I will do is turn the thread shank diameter. I will not thread it at this time. More on that decision later.

6. With the thread shank turned, I will bring the steady rest into contact with the bearing surface of the thread shank and dial it it.

7. From here, if the barrel is for a pre-64 Win, Springfield, Enfield etc, that requires a special CRF design breech cone, then I will machine this now, followed by the chambering and polishing operation.

8. After the chamber is finished, I will replace the tail stock in the breech end of the barrel, remove the steady rest and then cut the thread.

9. Once all this this is complete, I will make the final cut on the shoulder to set the headspace, thereby completing the job. I always hold just short of the required shank length. This allows me to make the final headspace adjustment before dismounting the barrel from the lathe.

When using a steady rest, I prefer to run the tail stock on a clean bearing surface, free of anything that could cause the slightest bump like threads. Other folks are perfectly happy running the steady rest on threads, and that is fine and they should do that which works for them.

After the headspace is set, I will then remove the barrel and bring it muzzle first, back through the headstock and into the chuck, to square and crown the muzzle. I will dial in the muzzle, using the extra length I previously turned for the chamber and threading operation.

By performing the chamber and threading operations like I described above, It is easy to maintain the bores zero from start to finish. Of course, you can get the same results while using less steps, if you run the barrel directly in the chuck. But if you have no choice, then doing the job between centers, and with the aid of a good steady rest, you should beable to turn out excellent work.

Good luck,

Malm

[ 07-28-2003, 04:04: Message edited by: G.Malmborg ]

Both methods will work very satisfactorily...through the chuck, or between centers.

I certainly would not worry about chambering with the barrel chucked through the headstock. If you took all the benchrest barrels that have been been chambered that way and then have won benchrest matches, set records, etc., you'd likely have enough to fill a long freight train.

Centering with the barrel in the headstock is probably best done by indicating the bore, or by indicating a range-rod placed in the bore, but properly centered I think the roundness of the chamber will be determined by the quality of the reamer and the quality of the workman.

AC

[ 07-29-2003, 00:09: Message edited by: Alberta Canuck ]

Thank you for the replies,

I do have one other question for you, if I mounted the barrel in the chuck for chambering which you state is also very accurate, do I need to use some type of work holding devise on the back of the spindle bore to provide a two point hold, or will a centered barrel simply held in the chuck provide enough accuracy to do a quality chambering job?

Thanks for the thoughts!

Good Shooting!!!

50

A spider is usally used on the back side of the spindle