38sp - 357 case capacity question

[mcb]

I never check into figures that are irrelevant 38 cases are much thinner & designed for up to 20 psi 357 mag cases are much heavier & designed to withstand 37500 psi so loading weak low power loads in 357 cases makes it harder to seal off the case & get good seal in chamber...in other words
LOAD 357 loads in 357 mag brass ....load plinking loads in 38 brass
No reason to complicate it more than that.
I simply seat cast Bullets in crimp grove as well & shoot them at the length they are

This is not true with modern 38 Special and 357 Magnum brass. The cases are coming off the same machines made to the same dimension except for the trimmed length and stamp on the case head.



Top to bottom: All Remington nickle plated cases, 357 Mag, 38 Special +P, 38 Special. There was less than .010 variation in case head thickness between the three and the web was exactly the same thickness.

 

[rfwobbly]

You can use distilled water, fill each case and determine the volume.

But you must use distilled water because that's the only water that realizes this is a math question and not a reloading question.

 

[kidneyboy]

The internet strikes again.

Yep. Sometimes I forget that THR is on the interwebs.

 

[MEHavey]

OAL's being what you quoted between the 38/357 loads...
you are actually losing usable case capacity going to the 357 set-up.




("Counterintuitive" Yup. But someone else run QL and check me)

 

[Rule3]

But you must use distilled water because that's the only water that realizes this is a math question and not a reloading question.

Only Lab Grade RO/DI pure H2O (this is THR!)

https://www.zoro.com/labchem-chemic...f382202a1eec1b9c5fcc409eeea685fa&gclsrc=3p.ds

 

[kidneyboy]

But someone else run QL and check me

Good luck with that. That's what I was asking for in my first post.
We are past all of that now and talking about distilled water.

 

[mcb]

Good luck with that. That's what I was asking for in my first post.
We are past all of that now and talking about distilled water.

I looked in QL and QL reports a Max Case Capacity of 38 Special at 1.500 cc and 357 Mag at 1.662 cc (<- Quickloads in my experience is super conservative with case capacity and I would not trust these numbers until I have actually measured my own cases, I rarely find the QL case capacity matches my own measured case capacity.)

If I seat a .7 inch long bullet in the 38 Special to 1.560 OAL I get a usable case capacity of 1.032cc
If I seat a .7 inch long bullet in the 357 Mag to 1.590 OAL I get a usable case capacity of 1.005cc

I am not sure what OP original case capacities are reported by his Lee manual refer to, since "1.30cc for 38sp and 1.36cc for 357" does not match the max or usable case capacity I am seeing in QL.

-------------------
ETA: I was bored so I measured two cases. Put them on my scale, zero'ed the scale and filled them with water (tap not distilled )

Fired Remington nickel-plated 38 Special: 1.56 cc
Fired Remington nickel-plated 357 Mag: 1.74 cc (my 357 Mag cases were shorter (by .013) than QL but greater volume)

As you can see the measured case volume is larger than what is reported by QL. Using these updated numbers.

If I seat a .7 inch long bullet in the 38 Special to 1.560 OAL I get a usable case capacity of 1.092
If I seat a .7 inch long bullet in the 357 Mag to 1.590 OAL I get a usable case capacity of 1.103cc

----------
Final caveat, I did this pretty fast so I might have screwed up somewhere and I only measured two cases and I would typically do more and average.

 

[kidneyboy]

I looked in QL and QL reports a Max Case Capacity of 38 Special at 1.500 cc and 357 Mag at 1.662 cc (<- Quickloads in my experience is super conservative with case capacity and I would not trust these numbers until I have actually measured my own cases, I rarely find the QL case capacity matches my own measured case capacity.)

If I seat a .7 inch long bullet in the 38 Special to 1.560 OAL I get a usable case capacity of 1.032cc
If I seat a .7 inch long bullet in the 357 Mag to 1.590 OAL I get a usable case capacity of 1.005cc

I am not sure what OP original case capacities are reported by his Lee manual refer to, since "1.30cc for 38sp and 1.36cc for 357" does not match the max or usable case capacity I am seeing in QL.

-------------------
ETA: I was bored so I measured two cases. Put them on my scale, zero'ed the scale and filled them with water (tap not distilled )

Fired Remington nickel-plated 38 Special: 1.56 cc
Fired Remington nickel-plated 357 Mag: 1.74 cc (my 357 Mag cases were shorter (by .013) than QL but greater volume)

As you can see the measured case volume is larger than what is reported by QL. Using these updated numbers.

If I seat a .7 inch long bullet in the 38 Special to 1.560 OAL I get a usable case capacity of 1.092
If I seat a .7 inch long bullet in the 357 Mag to 1.590 OAL I get a usable case capacity of 1.103cc

----------
Final caveat, I did this pretty fast so I might have screwed up somewhere and I only measured two cases and I would typically do more and average.

Thanks! Looks like the actual answer is - it depends, or, YMMV
Although not using distilled water probably invalidates the whole thing........

This is what I get for looking at something with a curious eye.
Not that there is anything wrong with that.

 

[MEHavey]

But someone else run QL and check me

Good luck with that. That's what I was asking for in my first post.
We are past all of that now and talking about distilled water.

Actually.... my Post#29 was because I had run QuickLoad
It's near a complete wash velocity-wise, except the 357 load-out runs 600psi higher, for almost no gain in speed.

 

[MEHavey]

For our purposes today.... water is water
(Not enough room on the pinhead for all the angels)




BTW: I pretty much max'd out the best combo of powder volume/pressure/burn-completion/velocity for 5" barrel in Post#29 -- Vita_N105 at 38SP/+P
Pressure

 

[Rule3]

Case capacity will vary depending on the brand of brass ((some are thicker)
So add or subtract that from the slide rule

 

[rfwobbly]

For our purposes today.... water is water.

Not so hasty... Water is only water at sea level. If you're in Wyoming on the Continental Divide, then the California side will have more rules and regulations. If you're in Ireland, Scotland, or western North Carolina, then no matter what the locals say, it's most likely a byproduct of grain.

 

[MEHavey]

Aqua vitae in that case....