I am strongly considering necking down some 30-'06 brass for my 25-'06, but here is the question: I have read where some have had to outside neck turn after doing that, but the reloading manuals I read say that brass for the quarter bore is easily made by simply necking down the '06 brass. So: which way is it? Any of you actually do that, and what was your experience? Did you have to outside neck turn after necking down? (I am familiar with the potential for uneven neck thickness and will deal with that if I have to, I guess...)

The definitive answer is, Yes, to all of your questions. And no. Maybe. It depends on your brass and your chamber. I have made 25s from 06s and they worked in a Ruger 77. If you have thicker 06 brass and a smaller chamber neck, it might not work without neck turning or reaming. Why don't you try it and tell us? You will have your answer in about one minute.

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Why don't you try it and tell us? You will have your answer in about one minute.

Because it isn't that simple... it is entirely possible that I may be able to chamber a handload without any problem, but the chamber neck be tight enough to jack pressures through the roof when the round is fired.

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Originally posted by Doubless:

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Why don't you try it and tell us? You will have your answer in about one minute.

Because it isn't that simple... it is entirely possible that I may be able to chamber a handload without any problem, but the chamber neck be tight enough to jack pressures through the roof when the round is fired.

You can always start with reduced loads and work up as I have.Your individual rifle and brass on hand will lead you to your answer. roger

Take a 25.06 case that has been fired in your chamber and mic the neck diameter.

Neck down a 30.06 case, seat a bullet in it and mic that loaded dummy case.

If the loaded dummy case measures equal to or smaller than the fired (un-resized) 25.06 case then you are good to go.

Huh? If it chambers easily, that tells you that it is safe. No one said for you to force a round into your chamber and fire it. No one can tell you how your individual components and rifle will work with each other until you try it. Drop a dummy round in your chamber and see if it goes in fully. If so, shoot. If not, you need to investigate more.
It is really that simple; it's not rocket surgery.

I bought one of the first Remington 25-06s when it was made a factory round about 1971 or 1972.

I formed LC-66 Match brass to use in it without any issues.

If I were to to do this to day with a different rifle here is how I would do it.

Take a tapered punch like a long center punch or spitzer bullet. Expand the case mouth of a 25-06 case to a funnel shape to oversize for the 25-06 chamber neck. It must be oversize enough to require being forced into the chamber neck. Take the expanded case put it in the chamber and force it home with the bolt.

Extract and measure the diameter of the case mouth. That diameter will be the maximum diameter of the chamber neck. You can repeat with other cases to verify your work.
Compare your measurement to your loaded rounds.
If your loaded rounds clear by at least .002 I would not worry about it.

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Originally posted by Doubless:
I am strongly considering necking down some 30-'06 brass for my 25-'06, but here is the question: I have read where some have had to outside neck turn after doing that, but the reloading manuals I read say that brass for the quarter bore is easily made by simply necking down the '06 brass. So: which way is it? Any of you actually do that, and what was your experience? Did you have to outside neck turn after necking down? (I am familiar with the potential for uneven neck thickness and will deal with that if I have to, I guess...)

Have made several hundred 30-06 into 25-06, starting before it was a factory cartridge. No problems if you start 10% below book max and work up, all as recommended in every reloading manual. When you change brass mfgr, start over due to different web thickness, etc.

Will work just fine, so long as you don't get frisky on starting loads.

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Take a tapered punch like a long center punch or spitzer bullet. Expand the case mouth of a 25-06 case to a funnel shape to oversize for the 25-06 chamber neck. It must be oversize enough to require being forced into the chamber neck. Take the expanded case put it in the chamber and force it home with the bolt.

Extract and measure the diameter of the case mouth. That diameter will be the maximum diameter of the chamber neck.

Actually, since the brass will spring back after being forced into the chamber, it will show a slightly larger neck diameter than the true neck diameter. That is why God invented Cerrosafe...


.

All I can say is to verify what many others here have already told you. I haven't been without one or another .25-'06 for over 60 years. Most were factory rifles, a couple were full-out custom jobs.

I have never bought or used a single round of factory .25-06 brass in all those years. Having several bushels of military brass on hand, I just sort them by headstamp, remove the primer crimps from the crimped ones, size them in a .25-06 sizer die, trim for length, chamfer case mouths, and load hem up.

Almost all my .25-06 ammo (several hundred rounds on hand at any time) is loaded in SL56 and SL52 brass.

Once I did try partial neck turning just to even up case neck thickness for accuracy, but didn't do it again as the accuracy did not improve significantly.

Yep, if it chambers without resistance then it is a foregone conclusion that the neck is not too thick to allow the bullet to exit the case without spiking pressures.

Due to the springback phenomenon you can actually have fired brass which will not allow a bullet to re-enter the neck and still be okay, but I prefer to neck ream if the necks of fired brass are too small to allow a slip fit.

Nimrod,
Since you have not tried this you do not know that it does not spring back and Cerrosafe is not needed, is also more expensive, more trouble and practically everyone has a free case to use.
It is very easy to slide such a case back and forth in the chamber with the bolt to veryfy that there is no perceptible drag. Like I said above you can test your work for free with 2 or 3 cases and have a very high confidence level.
If there is any spring back at all it is no worse than the dimension error you get with Cerrosafe. Like all engineered products they are never perfect. And Cerrosafe only has a small window of time for measurement. yeah it works great for chamber casts but it is totally unnecessary for checking a simple neck diameter.
In many cases you can even do that with a small hole gauge. But like Cerrosafe most users will not have small hole gauges either. As it is I have 3 or 4 methods and I like the expanded case method the best for checking necks.

Sorry nimrod but you are tally effing wrong.
Go try it before you shoot off your mouth.

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Originally posted by TX Nimrod:

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Take a tapered punch like a long center punch or spitzer bullet. Expand the case mouth of a 25-06 case to a funnel shape to oversize for the 25-06 chamber neck. It must be oversize enough to require being forced into the chamber neck. Take the expanded case put it in the chamber and force it home with the bolt.

Extract and measure the diameter of the case mouth. That diameter will be the maximum diameter of the chamber neck.

Actually, since the brass will spring back after being forced into the chamber, it will show a slightly larger neck diameter than the true neck diameter. That is why God invented Cerrosafe...


.

Bullets fitting or not fitting the case necks if often more of a function of temper or state of anneal. If you have well annealed brass the cases do not spring back much when fired.
However US GI brass that is not annealed will often still grip a bullet after being fired.

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Originally posted by Stonecreek:
Yep, if it chambers without resistance then it is a foregone conclusion that the neck is not too thick to allow the bullet to exit the case without spiking pressures.

Due to the springback phenomenon you can actually have fired brass which will not allow a bullet to re-enter the neck and still be okay, but I prefer to neck ream if the necks of fired brass are too small to allow a slip fit.