Rifle Re-Chambering Question
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    Default Rifle Re-Chambering Question

    I have a question about either cutting a current chamber deeper and setting the barrel back or say cutting a chamber deeper to make it an AI or some other improved version of the current caliber. The chamber is already cut of course and all barrel work done. How do you go about setting up the barrel in the lathe? What I mean by that is I have recently tried that just playing around and basically I removed the runout from the muzzle end and a spot just about 1/4" in front of the current cut chamber so I could check the actual bore. Then once that was all zeroed out, I indicated the chamber and the chamber is about .008 out. So if I were to just cut the new chamber like that, it would obviously oversize the chamber since the case size is the same as before. Do I just indicate the chamber in to recut and go with it? I am still pretty new at this and just playing and learning on old barrels and such right now.

    Thanks,
    Greg

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    Remember, your reamer will follow the existing chamber regardless if you indicate it in at the throat. That being said the only way I know to properly do it you will have to cut the old chamber off and start over.

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    Has the barrel been assembled and fired and you want to change something? Did it work alright before?
    I recently built a 35 Krag. The original reamer was too tight just in front of the rim and would extract hard even with an unfired case. PTG made a new reamer for me but the gun was assembled in a way that it could never go back the same way if disassembled. So I built a reamer extension and reamed it by hand. Used a thin brass washer on the reamer for a stop so as not to change the head space on the rim.
    If your barrel up is in not a super precision target set up pushing it in by hand and let it follow the old reamed chamber may be an option. .008 TIR is only .004 of center. There are probably a lot of guns out there like that that shoot OK.

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    If chamber and bore are that far out,you need to be careful not to break the reamer pilot.......you should also calculate if you will cut out all the all chamber ,including runout......personally,I like the method of an old cntributor to this forum,who had a somewhat flexible setup ,with the reamer supported by a lathe center and the existing chamber,and drove the reamer with a tapwrench and hand pressure......meaning if the reamer jammed ,you simply released the wrench,and it turned freely while the lathe was stopped.

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    Quote Originally Posted by FredC View Post
    Has the barrel been assembled and fired and you want to change something? Did it work alright before?
    I recently built a 35 Krag. The original reamer was too tight just in front of the rim and would extract hard even with an unfired case. PTG made a new reamer for me but the gun was assembled in a way that it could never go back the same way if disassembled. So I built a reamer extension and reamed it by hand. Used a thin brass washer on the reamer for a stop so as not to change the head space on the rim.
    If your barrel up is in not a super precision target set up pushing it in by hand and let it follow the old reamed chamber may be an option. .008 TIR is only .004 of center. There are probably a lot of guns out there like that that shoot OK.
    Thanks for your help, yes, its just a Remington 700 with their sendero/varmint contour barrel and I am going to do a re-barrel on it but I was just thinking if I trued up the action and say reamed the chamber out again but deep enough to have a new neck section reamed (since I don't know the exact neck dims of the factory reamer) would it shoot better since i would make sure everything was set up correctly. My plan was going great until I figured out the current chamber is not centered on the bore and my biggest fear was if I do ream I might break my reamer since the pilot will want to follow the bore but the reamer will try to follow the chamber or over ream the chamber if not. I have another barrel that is going on the rifle, I just enjoy playing and learning and this is how I do it so I don't care about the barrel but I do care about my reamer. Unfortunately this barrel only has 2" of 1.20" shank to thread and chamber so I can't just cut off the current chamber and rechamber. If I had 5" like many, that would have been my route so I figured it would be a fun project but not at the expense of my reamer. And I am getting what I wanted out of the project which is knowledge by you guys giving me out of the box ideas if I am ever forced to go down one of these roads. Thanks again for your thoughts and ideas.

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    On a new chamber, I indicate at the throat and bore the hole to within .010 of the shoulder diameter before chambering.

    Setting back the barrel, you're kinda stuck with what you already have. I indicate at the entrance to the chamber and use a JGS floating reamer holder to avoid enlarging the chamber diameter.

    Just last week I re-chambered two .260 Remington barrels to 6.5 PRC. The shoulder diameter of the new cartridge was large enough I could treat the project as a brand new chamber and bore to diameter.

    I always set the barrel back at least the length of the neck. That portion of the chamber is parallel sided and I want to be sure it cleans up.

    Sent from my Pixel 2 using Tapatalk

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    Thanks John,

    You hit the nail on the head with my concern and that was breaking the reamer. This project was just for fun and I planned to trash the barrel anyway so I am not about to break my reamer over it... That does sound like an interesting method though and I suspect if I put a smaller bushing on the pilot where it had a small amount of play maybe it would not bind so bad if the pilot was trying to follow the bore and the reamer was following the chamber. And like you mentioned, worse come to worse, just let go and let it spin with the barrel. Thanks for the idea, I will store that one in the back of my mind and I can see myself needing to use something like that one day.

    Thanks again.

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    Quote Originally Posted by fishingreg View Post
    Thanks for your help, yes, its just a Remington 700 with their sendero/varmint contour barrel and I am going to do a re-barrel on it but I was just thinking if I trued up the action and say reamed the chamber out again but deep enough to have a new neck section reamed (since I don't know the exact neck dims of the factory reamer) would it shoot better since i would make sure everything was set up correctly. My plan was going great until I figured out the current chamber is not centered on the bore and my biggest fear was if I do ream I might break my reamer since the pilot will want to follow the bore but the reamer will try to follow the chamber or over ream the chamber if not. I have another barrel that is going on the rifle, I just enjoy playing and learning and this is how I do it so I don't care about the barrel but I do care about my reamer. Unfortunately this barrel only has 2" of 1.20" shank to thread and chamber so I can't just cut off the current chamber and rechamber. If I had 5" like many, that would have been my route so I figured it would be a fun project but not at the expense of my reamer. And I am getting what I wanted out of the project which is knowledge by you guys giving me out of the box ideas if I am ever forced to go down one of these roads. Thanks again for your thoughts and ideas.
    Did you re-cut the threads in the action preventing you from just picking up the threads on the barrel and moving then forward?

    Sent from my Pixel 2 using Tapatalk

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    Quote Originally Posted by pat_j0nes View Post
    On a new chamber, I indicate at the throat and bore the hole to within .010 of the shoulder diameter before chambering.

    Setting back the barrel, you're kinda stuck with what you already have. I indicate at the entrance to the chamber and use a JGS floating reamer holder to avoid enlarging the chamber diameter.

    Just last week I re-chambered two .260 Remington barrels to 6.5 PRC. The shoulder diameter of the new cartridge was large enough I could treat the project as a brand new chamber and bore to diameter.

    I always set the barrel back at least the length of the neck. That portion of the chamber is parallel sided and I want to be sure it cleans up.

    Sent from my Pixel 2 using Tapatalk
    Thanks,

    I thought through that and thought if I was going with a bigger diameter case, this would not be an issue but since it is a .223 Remington and will stay a .223 Remington I felt like there was nothing I could really do to square it up and also felt I might get my reamer in a bind. I did think though, if I had a bigger bolt face I could open up to say a Valkyrie or something and make that work since I could indicate on the bore and bore a hair under as you mentioned to square everything up. I was on the same track as you on reaming far enough forward to ream the entire new neck length, that was in my plan but once I saw it was .008 out I got concerned if I did ream it I would possibly break my reamer and this being a play project I was not willing to do that. Thanks again for you help and thoughts.

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    If you run the reamer in with the bushing the reamer will follow the old chamber. Do the Valkyrie by indicating the throat and pre bore about .250 deep with a short solid carbide boring bar. Now run your reamer. I have been rebating rims on my lathe for many years. You can rebate them to 223 size as this has been done on comp rifles in the old days and the present.

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    Quote Originally Posted by pat_j0nes View Post
    Did you re-cut the threads in the action preventing you from just picking up the threads on the barrel and moving then forward?

    Sent from my Pixel 2 using Tapatalk
    No I purposely did not touch the threads on the action since I was considering using the already threaded barrel. I just did the lugs, action face, bolt lugs and bolt face but I will now though since I have decided not to bother playing with the old barrel.

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    Quote Originally Posted by Butch Lambert View Post
    If you run the reamer in with the bushing the reamer will follow the old chamber. Do the Valkyrie by indicating the throat and pre bore about .250 deep with a short solid carbide boring bar. Now run your reamer. I have been rebating rims on my lathe for many years. You can rebate them to 223 size as this has been done on comp rifles in the old days and the present.
    I had not thought about rebating the rim on the case to chamber a Valkyrie with a .223 bolt face. You have found that leaves plenty of rim to grip with the extractor I assume? Thanks for the idea.

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    If you aren't setting it back and just opening up an existing chamber, simply chuck the barrel in a 3-jaw chuck and use a floating reamer holder.

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    Quote Originally Posted by 300sniper View Post
    If you aren't setting it back and just opening up an existing chamber, simply chuck the barrel in a 3-jaw chuck and use a floating reamer holder.

    300 sniper, I believe he said the chamber was not coaxial to the bore.

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    Quote Originally Posted by Butch Lambert View Post
    300 sniper, I believe he said the chamber was not coaxial to the bore.

    I failed to read that....

    Without setting it back, it's going to be hard to recover from .008" of runout, if that is really what it is, unless you are going to a much larger bodied case. Personally, if the bore just in front of the throat and the throat are the same, I'd still just use a floating holder and not worry about it. Chances are, the runout shown now is due to different ways of being setup.

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    Agree with 300s comments. Likely the breach was originally dialed in at two points and the muzzle was allowed to go where it goes. Theoretically you could try to dial in the ahead of the throat and the breech end of the chamber and check the rest of the chamber for runout. Let the muzzle end wind up where it winds up when the breech end is straight, time the muzzle end to be at 12 oclock.

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    I'd try putting the muzzle in the chuck and putting a steady rest on the thread and see how the chamber looks.

    Re Valkyrie, PTG has a bolt for it.

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    Quote Originally Posted by Sea Sick Steve View Post
    Agree with 300s comments. Likely the breach was originally dialed in at two points and the muzzle was allowed to go where it goes. Theoretically you could try to dial in the ahead of the throat and the breech end of the chamber and check the rest of the chamber for runout. Let the muzzle end wind up where it winds up when the breech end is straight, time the muzzle end to be at 12 oclock.

    Steve, he said it was a factory Remington barrel. They are not indicated in to chamber. They are hammerforged.
    I also think he said he indicated the breech and the bore and that is how he found that they were not coaxial.

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    Quote Originally Posted by Butch Lambert View Post
    Steve, he said it was a factory Remington barrel. They are not indicated in to chamber. They are hammerforged.
    I also think he said he indicated the breech and the bore and that is how he found that they were not coaxial.
    Sorry missed that part

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    Thanks everyone for your replies, this served me very well and is exactly what I was hoping for, and that was to learn all the different thoughts and ideas everyone has. I am pretty green at this and I find I can learn more from 5 or 10 people throwing in their thoughts and ideas than I can any other way and then explore from there based on all your ideas. I appreciate your time to help out. In the end on this one I am going to chamber a new barrel I have for it but I have not thrown out the idea of trying a few of these ideas or combining a couple ideas and giving it a shot just to learn and get a feel for the outcome since I have the barrel to play with.

    Thanks again,
    Greg


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