Soft brass / tight chambers

H

hemiford

Well-Known Member
Joined
Oct 7, 2013
Messages
486
Just thinking again.
Can soft brass be prevented from expanding/flowing too much when firing by using a slightly undersize "tight" chamber ?

What are the perils of doing this ?

Does extraction become a problem ?

If you kept the chamber spotlessly clean, would this be feasible and safe ?

What are the perils of having the cartridge fit tightly in the neck of the chamber ?

I would think that resizing the brass would be a minimum per resize.

*******************

Would this be the same as firing a cartridge and then not resizing it ?
 
Last edited:
Match chambers are cut to be .003" above SAAMI minimum spec. If you want tighter, design your own reamer to suit, but clearance is required in the neck, I prefer .003" clearance in the neck. The other issue regarding brass being soft, is that all US brand brass is .005" under size in all dimensions, if soft, it expands in weird ways, being thicker on one side than the other from the drawing process.

The other point regarding this is SAAMI reamers nearly always cut long chambers, we eliminate this as best we can, but when the go gauge says it's good, we actually don't know the ACTUAL measurement until a round is fired and measured. I cut the final steps in .001" increments because I want the absolute minimum headspace. I have a micrometer adjustable stop for this, but even then my chambers often vary by .001" in headspace even if all else was the same set-up.

Cheers.
 
Rosebud said:
If you are a bench shooter this sounds reasonable. But a hunting rifle, not so much. Having a stuck case can be very, very bad in the mountains.
Click to expand...
This isn't going to happen when brass is undersized .005" from the factory. Norma and Lapua brass, amongst other Euro brass, is not undersized like US brands, so, match your brass to your chamber and there will be no issue. Large clearance is actually worse than tight clearance, except in headspace dimension.

Cheers.
 
VinceMule said:
Soft brass = garbage. I would not even give to someone that I did not like.
Click to expand...
Well, Norma is quoted as being soft, but it actually isn't, the problem with Norma brass is the webs are very thin, primer pockets open accordingly early, however, dimensionally it is very good.
As long as you don't run max pressure through it, it lasts very well.

Cheers.
 

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