case capacity


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kennedy
April 20, 2008, 09:06 PM
I am loading .308 in rem 700 with 168gr matchkings using H4895. My most accurate load has been 41 gr in win brass, I also have rem and federal brass, but can`t get the accuracy out of them(.6 in at 100 yds repeated)so I thought I would measure the the capacity of the cases and heres what I found measuring 3 times and taking the average(I filled the case to the top with powder then weighted the powder)
win 52.9 grs
rem 52 grs
fed 51.1 grs
So I am going to load up some loads as follows
win 41 grs
rem 40.1 grs
fed 39.2 grs
Looking closer at my reloading book they used win brass as the test, so I will use it as my base for adjustments to the other brass. Hope it works

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USSR
April 20, 2008, 09:29 PM
kennedy,

The proper way to measure for case capacity is with water. That way, it is not constrained to a particular powder. With water, the capacity should be in the neighborhood of 55 grains (give or take a little). That being said, your Winchester brass should have the most case capacity, and the Fed the least, as you noticed. Your Winchester load is quite light, and you may find more accuracy with the Rem and Fed brass by increasing your charge weights in those cases.

Don

kennedy
April 20, 2008, 09:38 PM
Don, tried increasing the load with rem and fed and it did not work, also 41gr is the starting load in both my reloading manuals. I am going to look at the loads using a percent and see if that works better rem at 40.3 and fed 39.6. I zeroed my scope using 41 gr in win, but when I use the same load in rem and fed, they shoot high, so I think I need to keep the presure constant by reducing the load in the smaller capacity cases.

Bullet
April 20, 2008, 11:25 PM
You might look here -

http://www.6mmbr.com/308win.html


.

USSR
April 21, 2008, 09:32 AM
Just to give you an idea of charge weight, I have reloaded for a buddy of mine the following for LR competition:

Remington brass
175SMK bullet
Fed 210M primer
43.6gr IMR4895
OAL of 2.860"
velocity of 2650fps

While I realize that IMR4895 and H4895 are slightly different, they are not that much different in charge weight comparisons. Starting loads are bare minimum loads, and you are expected to work up from there. There is more than one accuracy "node", and while you have found one with 41.0gr with Winchester brass, there is likely another one at 43+ grains that will give you more performance.

Don

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