Reaming chamber to 300 wm

Barkbuster20

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Nov 19, 2020
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Rainier, or
I have a 1903 springfield that I bought a few years ago that had been reamed out to 30-338 wm - I bought a set of 30-338 wm rcbs dies and my resized once fired 338 wm and once fired 7mm rem mag cases will barely allow the bolt to close - new brass neck sized chambers fine. I alsocouldnt hardly chamber resized 7mm brass using my 7mm dies so im certain its a short cut chamber and not the dies.

How difficult and expensive would it be to ream the chamber out to 300 WM? Would be more practical then a wildcat. Was also thinking of reboring to 338 wm or 358 Norma but I dont really want to put a lot of money into this rifle. Just want it to be a bit more practical.

**also want it to be properly chambered - would have left it 30-338 but if it needs more cutting there is no point not going to 300 WM
 
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can1010

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Feb 27, 2012
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1,131
if new brass chambers fine use new brass. the once fired brass if really once fired was fired in a looser chamber and expanded right above the belt this is common and right where your standard died cant resize the brass. you will need a specialty collet die to help fix the old brass but just getting new brass and fireforming to your chamber will end up cheaper in the end
 

shortgrass

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Mar 31, 2010
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Once you have the collet die, made by Innovative Technologies (larrywillis.com), and use it to re-size your brass that's been fired in a different rifle your problem will likely disappear. New brass seems to be scarce and pricey when you find it. The collet die may be lower in cost verses the cost and frustration of trying to source all "new" brass. Not to mention the cost to re-chamber......
 

Barkbuster20

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Nov 19, 2020
Messages
45
Location
Rainier, or
It could be the base - I was thinking it was the shoulder being too far forward. Its been a while since I have messed with it so I should probably check that again. - I do have 50 pcs of virgin rem 338 wm brass set aside for it already because I use winchester brass for my 338.
 

shortgrass

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Mar 31, 2010
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Use a Magic marker or Dykem layout fluid to see where the 'bind' is. Careful necking down, that will thicken neck walls. Measure neck diameter after bullet is seated to make sure you have clearance (on 'bigger' calibers .004" or so). Thicker case neck walls will effect neck tension on the bullet, also. Necking up ill thin case neck walls. You don't want too much neck clearance, but you don't want too much, either.
 

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