Forming 7x57 from 30-06 - question

Dean2

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You guys are super helpful. Here's what I have:
Outside diameter after sizing: 0.306-0.308 (slight variance)
Outside diameter after firing: 0.323-0.325
Outside diameter with bullet seated: 0.308-0.309

By my math, clearance is atleast 0.015"-0.017"

GTG?
Wow, that is some loose neck. What is the outside diameter after you seat a bullet in the sized case. Even with the bullet in it you are probably WAY good to go. You are probably going to end up having to anneal those brass every 3 or 4 firings or the necks will split. I have never had that much neck clearance on any gun. Usually .005 or 6 from seated with a bullet would be max.

Just occured to me after I thought bout it a bit; Is the gun by any chance a military surplus version becasue if it is then the neck size makes perfect sense. Military chambers were made intentionally loose so all ammo fit, dirt didn't stop you from shooting and they never figured on reusing the brass anyhow.
 
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HuntingBronco

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Outside diameter with bullet seated: 0.308-0.309 (after sizing)

Impressive - I'll post a pic of the rifle. I inherited it and have done some flood damage repairs. Based on your reasoning, it might have the original barrel on it. Take a look at the pic...does it look like an original mauser barrel profile (I don't know much about these things) Would love it if I could go to Brownells and snag a short chambered barrel and screw it on...this one is a little rough....) inside and out.... But it is truly amazing in hand. I would be delighted to spend days and miles with this one in hand in the woods or mountains.
 

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Dean2

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Outside diameter with bullet seated: 0.308-0.309 (after sizing)

Impressive - I'll post a pic of the rifle. I inherited it and have done some flood damage repairs. Based on your reasoning, it might have the original barrel on it. Take a look at the pic...does it look like an original mauser barrel profile (I don't know much about these things) Would love it if I could go to Brownells and snag a short chambered barrel and screw it on...this one is a little rough....) inside and out.... But it is truly amazing in hand. I would be delighted to spend days and miles with this one in hand in the woods or mountains.
Impossible to tell from the picture and be 100% sure but given I can see a step in the barrel near the chamber my bet would be it likely is the original.. If you check the proof marks on the underside of the barrel you will quickly be able to tell the origin and close age of the barrel. Many rifles kept the original barrel as the 7x57 does not wear a barrel very fast. You can buy prechambered barrels from Douglas, or Shilen but you will need a smith to mount it for you. Also, if that is the original barrel it can often take some real serious equipment to get them out of the action if they have never been taken apart before.
 
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HuntingBronco

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Okay - thanks Dean. Just to be clear, do you mean the Douglas and Shilen offerings are close to original contour? That would be great, as I just bedded this thing.
I'm still having trouble chambering a round after fireforming. I think there is something janky with the chamber. Barrel is in rough shape any way, so I'll look into a pre-chambered barrel. I think Brownells carries a Shilen barrel - around $430 IIRC. I'll reach out and see what they have to say. Shouldn't I be able to toss this in the lathe and relieve it to ease barrel removal?
IMG_4809.jpg
 
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Dean2

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I would say that is the original barrel.
The rifle was proofed in Belgium as a rifled arm, for nitro powder.
Controller of Proof Codes
Letter with a * above it Name of the Controller of Proof
A
Woit Nicolas Cominoto
1911 - 1951

Because of the crown over the R is was proofed after 1924.
 

RT2506

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You will not get a fully chambered barrel that you can just screw on and be ready to go. The barrels are only partly chambered. You have to ream them a little at a time using head space gauges. These barrels are also sometimes really hard to remove. If you don't have the proper vice and action wrench you can and most like will warp your action. Unless you have the tools and really understand what you are doing GET A GUNSMITH to replace the barrel. You may find that it is best to just leave the old rifle alone and shoot it the way it is and take all that money and purchase you a new rifle. By the way that is a "small ring Mauser". It will not safely handle loads over 46000 CUP even with a new barrel. Keep in mind the rifle is also around 100 years give are take old. I have been fooling with these old rifles over 50 years.
 

HuntingBronco

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Update - changed shell holder and was able to get the case a little deeper into the die. The bolt now closes without force. Using Hornady headspace measuring tools, these are now about 0.002 longer than factory ammo and I am only getting between .001/.002 bump. I'll anneal each loading and keep an eye on the brass as I shoot it. I hope I can get sufficient accuracy from this barrel to allow me to keep it just the way it is..... I'll report - thanks for all the help and guidance thus far.
 

HuntingBronco

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Further update - got out today with the Mauser. First 3 shot group with the gun after full length bedding. considering the condition of the bore, I'm taking RT's advice and calling this one done.
 

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Dean2

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Nothing at all wrong with that. Many new guuns with pristine bores won't group that well. This will make an excellent stalking rifle.
 

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