Case capacities

[mustanggt]

I am trying to find the difference in case capacity between different brass manufactures. Specifically I'm working up loads in a M70 Winchester in 7x57 Mauser in Remington brass only. At the same time I'm working up loads in a M70 in .264 Win Mag and I was using Norma brass and Winchester. I got velocities on my chrony 150fps less in the Norma and about 150-200fps faster with the W-W brass. I weighed the brass and the Norma was 216gr and the W-W was 236gr. So that answers that question. That is the widest disparity in case capacity I've ever seen as evidence by the velocity difference. I am only able to get R-P brass now for the 7x57 and am looking at load data that calls for other brass (W-W) and want to see how much difference there may be in that caliber and judge per the 264 Win Mag load work up. Thanks

[runfiverun]

don't bother comparing the two different rounds take each on it's own merits.
as far as the brass goes you'll have to take them on a lot to lot basis, however in the x57 I'd bet the Remington brass weighs more than the Winchester.

for what it's worth I prefer Remington brass for my X-57 rounds.

[mustanggt]

My comparison is only because of the difference I noted per the 264. I've never seen a difference of that much maybe 5-10gr but never 20. I wouldn't have asked the question if I hadn't run across it during the load workup. 200fps more in velocity than what I expected from the book really gave me pause.

[runfiverun]

that's why I cringe when I see someone quote loads from the LEE book.
the loads are of course tested and printed [by someone else]
but LEE just re-prints them all jumbled together without giving the case or primer, and mostly without brand of bullet used.

since velocity is tied to gas volume and or pressure, I'd say your increase come from more pressure because of the smaller case. [I know duhhh]
I'm a bit envious that you can get X57 brass of any sort.
I'd buy a couple hundred cases and designate them to the rifle and work up the couple of loads I was gonna use then try to wear out the brass.

[mustanggt]

Thanks for the replies. I appreciate the help. I sometimes get lucky when I start to look for components I need. I've gotten pretty good at scrounging over the last several years. I'm working on this little project because of a pronghorn hunt in MT this fall providing we get the draw of course. Won't know till next month. So I've got a finite time to work but luckily the little loads I've worked out all gave me an 1" and under so I can't go wrong with that. Once that's complete I will hit the field for a lot of practice.

[runfiverun]

nice.
either round will do the job on those critters.
the 7x57 and the hornady 139 with rl-19 and a rem 91/2 primer behind it will get you over 2700 easily [I run the wifes at 2750 fps and little girls right on it's tails at 2725]
deer sized animals don't stand a chance, and that velocity allows the bullet to do it's job without tearing up meat.
they'll do it out to 300 yds [without a hold over with the standard 2" high at 100 sight in] and in close the bullets don't come apart.

[steve4102]

Case weight is not an accurate measurement of case capacity.

It is not uncommon(different headstamp) for a heavier case to have more case capacity than a lighter case and verse-visa. The only true way to determine case capacity id to test a "Fired" case with H20.

Here is an example of case capacity vs case weight. Note, there is no direct corralation between case capacity and case weight.

[mustanggt]

Thank you Steve. Where did you get that table?

[steve4102]

Thank you Steve. Where did you get that table?

http://www.6mmbr.com/223rem.html