Case volume ranking list???

[Russel Nash]

Hi all,

I was just wondering if there is an accepted ranking list of cases/calibers by their internal volume???

I guess we would say like the .50 BMG would be like rank number 200, for example.

And then something like the .204 Ruger would be close to the number 1 slot.


Thanks!

[Doc Highwall]

The draw back to that is usable case capacity after the bullet is seated is what is important and with a maximum overall length heavier bullets will take up more space. LEE has usable water capacity in his book that can be referenced.
Quick Load will do this but you also have to take case weight into consideration. The maxium case volume is not reached until the case is actually under pressure in your gun but you can get close enough with an unsized case taking into account the volume the bullet displaces in seating depth

[btroj]

I suppose that a general list could be developed but why? I don't see where it would have ALOT of practical application. I can tell a fair amount by looking at case size.
Doc has also hit on a big problem. Even if you used a generic bullet and seating depth this is a number that doesn't have a while lot of value.

[Rico1950]

I thought the "cc" reference in LEE's load book referred to cubic centimeters ( a volume). Wouldn't it refer to powder also since it's a volume and not a weight scale?

[Artful]

Yep CC's is volumetric measure usually measured by how much H2O it holds after you seat a bullet

You could rank them yourself
http://www.chuckhawks.com/rifle_case_capacity.htm

http://kwk.us/cases.html (0ff to the right)

But frankly there are many variables - did I use 300 blk or reformed 221 fireball or military 5.56x45 to make up this batch of 300/221 Fireball was that with 220 smk or 240 smk

[Russel Nash]

thanks!

I was just wondering how much case capacity 7.62X39 had.

then i wanted to compare to other calibers and then look to see what kind velocities they are putting out.

[Artful]

Lets see
30 carbine __21
221 Fireball _21
32-20_____22
357 Mag___27
5.56x45 ___31
357 Max___34
7.62x39___35.6
30-30_____45
7.62x51___54
308 Win___56

Notice the 2CC difference between commercial 308 and military 7.62x51 outside is the same but walls and base thicker on military.
Also notice in performance the 7.62x39 is very close to the 30-30 but has 9.4 CC less capacity so has to use higher pressure to make up for loss of volume.

[Doc Highwall]

It is not just case capacity's. It has to be case capacity for a certain caliber because it relates to expansion ratios and the barrel length.
You have to compare say 30-30 Win with a 308 Win because they are both 30 caliber.
A 22-250 Rem. has a greater case capacity then a 30-30 Win but the barrel volume is greatly different per inch of barrel. Also you have to take into account barrel length to determine if the case capacity is overbore or under-bore and any cartridge can be overbore if you make the barrel short enough.

[Russel Nash]

hey, thanks guys for all the responses.

I just remember that in say the past 4 or 5 years it seemed like some new Winchester Super Short Magnum (or whatever they were actually called) calibers seemed to come out every month. I guess the rifle manufacturers were looking to boost rifle sales.

the AK round is pretty danged short. and my reloading manual isn't new enough to list the new WSSM's rounds and their dimensions.

I started another thread in the cast boolits military rifles sub forum a couple of weeks ago, wondering if I could wring some more velocity out of the 7.62X39mm Russian.

anywhoo... i was just looking for ideas of calibers close in size to the Ak round.

[Doc Highwall]

The new cartridges are over bore for the short light rifles they are chambered in and kicking the snot out of the shooters so bad that they had to come out with managed recoil ammo.
It is a 10-15% increase in powder for a 3-5% increase in velocity and more rapid throat erosion.

[mroliver77]

Russel,
Good read on 7.62x39 +p. ;)
http://www.leverguns.com/articles/paco/762x39.htm

[Artful]

I like 1680 powder for max loading in 7.62x39 wilth J-word projectiles.

[303Guy]

Has anyone tried Lil'Gun in the 7.62x39? One has to be careful with that powder. If the case volume is too high it seems to limit the attainable velocy but otherwise it produces velocities higher than other powders at lower pressure.

[Doc Highwall]

303Guy, I like the velocities my self but others here mentioned something about flame temperatures being much higher causing faster throat erosion.
I think 44Man was the one who mentioned it.

[Baron von Trollwhack]

Donnelly and Trowsley's Manual of Cartridge Conversions book has both metric and US cartridges and the water capacities. Personally, as a matter of convenience, I just measured the weight in grains of all I load plus a few ( all full lengthed and primed ) using 748 powder to the midpoint of the neck, and made my own list. It is pretty close for most ball powders and a little over for stick powders, but still very useful with things like new data powders. BvT