270 win case water capacity.

[Sas874runner]

So I just measured case cap on a fired unsized case. Capacity measures 69.0 gr water. Does that seem high?

 

[jimbires]

I'd say your probably right . I checked quickload and it says 67.0 . this will vary due to case length , maker of brass , and chamber size . Jim

 

[DrMike]

Sounds well within the parameters of chamber measurements.

 

[Sas874runner]

Thanks guys. The reason I asked. My current load is 59 gr h4831sc wlr primer and r-p case. I have no pressure signs and chrono speed shows 2924 fps. 24" barrel. Even though this load is .5"@100 reloaders mentality to see if I can make the load better.

 

[NYDAN]

Coincidently, I measured the fired-unsized case capacity for my .270 Win today and found the following:

Nolser Cases - 71.14 gr. Ave.
Norma Cases - 71.32 gr. Ave.

which is even more than Sas874runner found with his.

I am not too surprised since I can see and measure that the diameter of the fired cases is larger than the new, unfired cases.

The Nosler reloading data show case capacities of 62.8 for the 150 gr. bullets, 63.7 for the 140 gr. bullets, and 64.6 for 130 gr. bullets.

Does the larger case capacity of my chamber mean that:
1. My measured velocities will tend to be less than the Nosler data?
2. My max load may be greater than "book" data?

Are there adjustments or considerations I should think about due to my case capacity?

Does a larger chamber diameter have any affect on accuracy?

Thank you for your thoughts.

Dan

 

[Sas874runner]

From my experiance it typically means a higher max load due to increased space and lower case fill. It should not affect accuracy unless you are Bumping the shoulder back to far and allowing the extra space in the chamber to keep the round from aligning with the bore as the bolt closes. I always like to adjust my dies back and size the case a small amount at a time until I have slight resistance on the bolt with the empty case in the chamber. Ensuring the case shoulder is pushed into the chamber and then aligning the bullet with the center of the bore. There was another post on here a while back about Max charges. I like sto start at min load and work up in .5 gr increments until I start to get flattened primers or a sticky bolt lift. At which point I back down 1 gr and call that max.

 

[bobnob]

Coincidently, I measured the fired-unsized case capacity for my .270 Win today and found the following:

Nolser Cases - 71.14 gr. Ave.
Norma Cases - 71.32 gr. Ave.
.........

Does the larger case capacity of my chamber mean that:
1. My measured velocities will tend to be less than the Nosler data?
2. My max load may be greater than "book" data?

Are there adjustments or considerations I should think about due to my case capacity?

Does a larger chamber diameter have any affect on accuracy?

Thank you for your thoughts.

Dan

My 270 with Win brass has 69.5g water capacity.

I find I need to use about 2g more powder than listed data, to achieve listed speeds. Generally.

My 150g load uses 3.3g over ADI/Hodgdon max data :shock: , yet chrony speeds and everything else are within the right parameters.

Start low and work up.

 

[Sas874runner]

That's the key. Slow and steady keeps your gun in one piece

 

[NYDAN]

Guys, thank you for sharing your experience and insight.