Setting back a .262 and going .269 --do I have this right?--

M

matchman

New member
My experience doing machining work is limited, I hope to get some input on my approach to what I plan to do.
I have a 6ppc .262 neck barrel I wish to set back and go to .269 neck.
(I purchased a finish reamer and go gauge)
1. Make cat heads for lathe headstock and a collar for the threaded barrel for shoulder/headspace reference to keep it the same. (to use depth mic)
2. I assume I should indicate the chamber end @ the groves of the rifleing or maby the lead in after the existing shoulder ?
3. Indicate muzzle off lands.
4. The reamer has the bushing/guide on the front and plan on doing the floating set up to perform the reaming.
5. Ream .020 deeper than previous?? (set back the chamber) and remove a equal amount off the barrel shoulder. (called the tenon?)
6. I assume I should reduce the cone the same amount ?
Thanks for any input.
Adam
 
matchman said:
My experience doing machining work is limited, I hope to get some input on my approach to what I plan to do.
I have a 6ppc .262 neck barrel I wish to set back and go to .269 neck.
(I purchased a finish reamer and go gauge)
1. Make cat heads for lathe headstock and a collar for the threaded barrel for shoulder/headspace reference to keep it the same. (to use depth mic)
2. I assume I should indicate the chamber end @ the groves of the rifleing or maby the lead in after the existing shoulder ?
3. Indicate muzzle off lands.
4. The reamer has the bushing/guide on the front and plan on doing the floating set up to perform the reaming.
5. Ream .020 deeper than previous?? (set back the chamber) and remove a equal amount off the barrel shoulder. (called the tenon?)
6. I assume I should reduce the cone the same amount ?
Thanks for any input.
Adam
Click to expand...


Adam, it sounds like you have it down pat; go for it!

Gene Beggs
 
If the barrel is worn a 20 thou set back is not really worth while doing... a quarter or three eighths of an inch would be better.
 
I purchased the rifle used and I have never fired it. I purchased new brass and wanted to start with a .269 neck and have the ability to set it back as needed in the future.
I do not have a bore scope to really determine anything definitive as to condition.
This is also a learning experience to get my feet wet before I butcher a new barrel maby next year.
 
With such a short set back you will not be able to pre bore anything in alignment with the throat. I would simply set up on the existing chamber as the reamer is going to follow it anyway, and run the reamer in just touching the shoulder and head space it correctly on your action.

I think you could even do it carefully by hand with the barrel held in a vise... you are only opening the neck a few thou with a piloted reamer...
 
Adam

I set my own barrels back on a regular basis. But, thisis simply to keep the throat very fresh, long before any noticeable accuracy falls off. I will go for about .025 the first two times, then the third time, (after about 700 riounds), Iwill chop the thread off and threat the barrel like a new blank. Some of the best aggs I have ever shot were with a barrel on the third set-back.

One thing you have to remember. When setting a barrel back, you have to be able to place the barrel back into the machine exactly the way it was when originolly chambered. All you have to do is to start a conversation about the different methods that shooters use to set barrels up to understand that unlessyou did it yourself, you will have no idea how it was set up in the beginnig.

Regardless of how you set it up, though, the reamer is going to follow the existing chamber. The pilot, which by it's very nature, has to have a tad of clearance, will not keep it from doing this. This a is simply a basic tenant of machine shop practice.

Resetting a barrel back up for a set-back is an exersise in compromise. I have converted many .262 necks to .269, but it has always been on a barrel that I originally did, so I knew exactly how to true it up. The chamber and everything else is running as true as it was before.

Set your barrel up. Then, run the indicater at the front of the chamber, and then the back. This is only a distance of about 7/8 inch, so you have to have a very accurate indicator. If the difference in the readings is less than .0003, then you will probably be ok. If more, then you have to make some sort of adjustment so that the body of the chamber is running as true as possible. Remember, that is what the reamer is going to follow as the reamer body starts to contact the sides of the chamber walls........jackie
 
Thanks for the details Jackie and everyone that responded.

With the un-known factor it sounds like I should just get my feet wet now and chop off the chamber and start fresh the barrel is at 22.5 " total length now.
Its a LV class rifle.
 
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Matchman

Just chop the body of the chamber off, that will give you about a 21 1/2 inch barrel, like I said before, just treat it like a new blank......jackie
 
matchman said:
Thanks for the details Jackie and everyone that responded.

With the un-known factor it sounds like I should just get my feet wet now and chop off the chamber and start fresh the barrel is at 22.5 " total length now.
Its a LV class rifle.
Click to expand...

If you are inexperienced and this is just as much a learning experience as accomplishing something, I would stick to your original plan and just run the reamer in .020" and take the same off the shoulder and cone.

This will be the easiest, allow you to get your feet wet, and may end up shooting very accurately if the barrel is in good condition.

You can always chop the tennon off and rechamber later if does not shoot accurately, but you cannot put metal back on if you change your mind..................Don
 
I'm wit' Don :)

In fact, I'd first of all try just cutting the new throat using the new reamer...... can you get it to headspace? If it comes out long you _can_ even re-neck some used brass and make rounds for it if you want.... Or better yet try turning it in just a small amount and reset the headspace. try to learn how well the new reamer matches the old one, where's it cutting? Is it cutting a perfect circle or out of line some?? Once you've got some sort of crush-fit, how does she shoot?

Now back 'er in a thread..... have another go......

Now you can whack it and set it back on the third go-round, learning all the way.

I personally would also try different setups each time, and keep notes.

al
 
You could just run the .269 reamer in by hand to clean up the .262 neck. The throat wouldn't be fresh, but you'd be able to see what it would do as is. You could always set it up in the lathe and set the chamber back later.
 
Mike Bryant said:
You could just run the .269 reamer in by hand to clean up the .262 neck. The throat wouldn't be fresh, but you'd be able to see what it would do as is. You could always set it up in the lathe and set the chamber back later.
Click to expand...

I was thinking the same thing.
 
Ditto the above, but I went from .262 to .268. Set the barrel verticle and turn very slowly. You are only taking off about .0035/side. Just make sure the reamer does not take any off the rear of the chamber.

Donald
 
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