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Kim Merrill
Guest
What group characteristics would be observed when rounds are fired with a slight excessive headspace?
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dmickey
Guest
I have two rifles with differing headspace. My .22 BR's headspace is exactly on the money. My 6mm BR has a headspace .005" long. Both will shoot one-hole groups (if I do my part!) The only problem is that with the 6mm I have to trim new brass after the first firing! As far as the groups are concerned, there is no change.
Kim,
A lot of different things come into play.Chamber/die compatibility being foremost.Bullet engagement into the lands.Firing pin protrusion/depth of primer pocket/hardness of primer,consistant reliable ignition,etc.
If everything is as it should be and you inadvertantly set up your sizing die with .017 shim instead of the predetermined .018 shim( if you even use that type of program)thus allowing.001 extra headspace the gun will in all probabilty still shoot as well as it had been but the brass will get un-necessarily over worked and will shorten it's life.
I'm not shure if that answers the question you were asking ? If not we'll try again.
Joel
A lot of different things come into play.Chamber/die compatibility being foremost.Bullet engagement into the lands.Firing pin protrusion/depth of primer pocket/hardness of primer,consistant reliable ignition,etc.
If everything is as it should be and you inadvertantly set up your sizing die with .017 shim instead of the predetermined .018 shim( if you even use that type of program)thus allowing.001 extra headspace the gun will in all probabilty still shoot as well as it had been but the brass will get un-necessarily over worked and will shorten it's life.
I'm not shure if that answers the question you were asking ? If not we'll try again.
Joel
M
mike in co
Guest
you would have to describe your version of "excess headspace". most saami specs are x.xxx plus 0.010( or so). while a br gun is set at zero, its not "excess" til its past 0.010......
no go gages are typically only zero plus 0.003
so it is a wide number...br gun excess is user defined....
mike in co
no go gages are typically only zero plus 0.003
so it is a wide number...br gun excess is user defined....
mike in co
Excessive headspace as in a chamber being .005" to long, or as in a cartrige being .005" shorter than the chamber?
As long as you don´t push the shoulders back to much, it won´t matter that the chamber is cut .005" past a no-go gage. Having .005" clearance in the chamber sure isn´t good, but it will probably won´t affect accuracy much. Your case life will suffer thoe.
As long as you don´t push the shoulders back to much, it won´t matter that the chamber is cut .005" past a no-go gage. Having .005" clearance in the chamber sure isn´t good, but it will probably won´t affect accuracy much. Your case life will suffer thoe.
L
Larry Elliott
Guest
As others have said the chamber headspace as measured with a headspace gauge shouldn't have any effect on accuracy as long as the cases aren't rattling around in the chamber. Since nobody shoots BR with anything but handloaded ammunition the headspace of the cartridge/chamber can be and usually is tightly controlled in the sizing process.
A lot is made out of excessive headspace being dangerous leading to all manner of evil from blown up guns to fallen arches. Anyone who has ever seen a fired .303 or .30-40 case from an SMLE or Krag and compared it to a new case can easily see that the shoulder has been blown forward by 1/8th inch or more. No problems at all unless or until someone sizes the case back to original size, loads it and fires it again. Then the heads fall off the cases like clockwork. The same thing happens with rimless chamber if the headspace is too large, although it usually takes a few more firings.
The main danger of excessive headspace is shortened case life.
A lot is made out of excessive headspace being dangerous leading to all manner of evil from blown up guns to fallen arches. Anyone who has ever seen a fired .303 or .30-40 case from an SMLE or Krag and compared it to a new case can easily see that the shoulder has been blown forward by 1/8th inch or more. No problems at all unless or until someone sizes the case back to original size, loads it and fires it again. Then the heads fall off the cases like clockwork. The same thing happens with rimless chamber if the headspace is too large, although it usually takes a few more firings.
The main danger of excessive headspace is shortened case life.
K
Kim Merrill
Guest
Thanks
After posting my thread I noticed that I left out my definition of slight, 0.003.
I use a set of matching dies to chamber, assisted by shims for fine tuning. After changing barrels the other day I was not particularly shooting very well. Conditions were terrible, cold, wet and switching winds. Welcome to Louisiana winter shooting.
When I got home and started working with my brass ,I found that I had been shooting with slightly more head space than I normal use. That is why I posted the question.
I went back to the range Friday and shot some respectful groups. Head space had nothing to do with a bad on the bench.
Thanks for the replies.
After posting my thread I noticed that I left out my definition of slight, 0.003.
I use a set of matching dies to chamber, assisted by shims for fine tuning. After changing barrels the other day I was not particularly shooting very well. Conditions were terrible, cold, wet and switching winds. Welcome to Louisiana winter shooting.
When I got home and started working with my brass ,I found that I had been shooting with slightly more head space than I normal use. That is why I posted the question.
I went back to the range Friday and shot some respectful groups. Head space had nothing to do with a bad on the bench.
Thanks for the replies.
L
Larry Elliott
Guest
Let me say from experience that if you're cold and shivering you won't be able to shoot your best. Maybe not even close to your best.