38/357 load data confusion

[james6600]

I was looking at Hodgdon's load data on TrailBoss with a 158gr cast LSWC, both the 38spl and 357 have a max of 4.2gr, 38spl has a velocity of 804fps at 13700PSI and 357 has a velocity of 865fps at 20400CUP. Now I know CUP and PSI are not the same but they usually run somewhat close and with the larger volume of the 357 case wouldn't pressure and velocity be lower? Hodgdon doesn't state what primer they use but assuming they use a mag primer in 357 would it make that much difference? If I separate the pressures and velocities I would think the 38 was a long barrel and the 357 was a short barrel, What am I not seeing here? James

[Tatume]

The CUP measurements were made before Hodgdon switched to a strain-gage pressure system. The difference could be just about anything (powder lots, machine operator, bullet alloy, etc.) or just random error. It could even be that the difference between CUP and PSI makes up a lot of the difference.

What I find to be more surprising is that the 357 load in the larger case has greater velocity. Again, it's not much difference, and could be any of the factors already mentioned, including random error.

[maclords]

You can see the primer used and barrel length from the Hodgdon site if you click the "print" button (you don't have to print it). It is wsp and 7.7" for 38 special and wspm and 10" for 357. Someone smarter than I can tell you about the pressure. different barrels, primers, equipment, conditions +\- errors maybe could make up for it.

[james6600]

So I went and loaded 4.2gr in a 38 and got 725fps then loaded 4.2 in a 357 with a mag primer and got 741fps and 738fps with standard primer. All this falls under standard deviation. Just thought this was interesting. James

[james6600]

Thanks for the replies. Tatume I found the same thing interesting and my test showed the same effect as Hodgdon's but the variance is so minute it could have been crimp difference. Hindsight I should have left them un-crimped. Looks like a test for later as I'm out of play time now.
Maclords thanks for the print button info I did not know that as I just take the laptop to the reloading room.

[bhn22]

I have several old Hodgdon manual, and they consistently used the same loading data for cast bullets in 38 & 357 for years. I doubt the 357 data was ever pressure tested.

[9.3X62AL]

This thread's content brings up something that my old casting and reloading mentor Leo Reyes told me when I was in my late teens. His view--and my own experiences bear this out to a strong degree--is that cast boolit loading data is at best an inference of what results you will receive in your firearms with castings, due mainly to the vast array of variables present and possible in these ventures. "With castings, you are more or less on your own when it comes to load testing and determination." Good ol' Leo--his words still bring a smile.

[JakeBlanton]

Although the .357 mag case (1.29") is longer than the .38 case (1.155"), the .357 mag bullet is seated deeper (if you are going by the maximum OAL in the SAAMI specs). As such, the powder space in both cartridges is VERY close to the same. There is only a 0.04" difference in the maximum OAL of the two cartridges (1.59" vs 1.55"), thus with the same bullet in both, the .357 mag has only 0.04" more powder space.

According to the SAAMI specs, the .357 mag has 0.3" of bullet exposed whereas the .38 has 0.395" exposed.

Now, the .357 max has a max OAL of 1.990" and a case length of 1.605", so it has 0.385" exposed.

The difference in the case length of the .38 and .357 mag was so that .357 mag could not chamber in a .38. It's quite possible that a .38 handgun could be strong enough for full power .357 mag rounds and all that would be necessary to convert it would be to rechamber the cylinder so that it was a bit deeper.

[Tatume]

Hi Jake,

You've said this before, and I confirmed it with SAAMI drawings, but nobody loads them to the same OAL. The 357 Magnum has more interior volume.

Take care, Tom

[bhn22]

This thread's content brings up something that my old casting and reloading mentor Leo Reyes told me when I was in my late teens. His view--and my own experiences bear this out to a strong degree--is that cast boolit loading data is at best an inference of what results you will receive in your firearms with castings, due mainly to the vast array of variables present and possible in these ventures. "With castings, you are more or less on your own when it comes to load testing and determination." Good ol' Leo--his words still bring a smile.

I like that. The key word is "inference". Being the analytical type, I read, and reread every page of every reloading manual I could get my hands on. I have dozens of them now. Patterns emerged. I finally developed the procedures I now use to divine suitable loads. It's more theory than anything else. I don't know that I could explain my procedures any better than Leo did. He pretty much nailed it.

[JakeBlanton]

Hi Jake,

You've said this before, and I confirmed it with SAAMI drawings, but nobody loads them to the same OAL. The 357 Magnum has more interior volume.


There is a lot of variance in the lengths that people load rounds. Looking over at the load database .38 special at Handloads.com (http://www.handloads.com/loaddata/default.asp?Caliber=38%20Special&Weight=All&type=Handgun&Order=Powder&Source=), I do see a couple of loads for an OAL of 1.55". Looking at the load database for .357 mag, I see OALs everywhere from just slightly longer than the case length to over the SAAMI specified maximum OAL. So, given this assortment of OALs for the two calibers, it's they are being loaded to the same OAL in some combination of powders and bullets. I searched around my gun safe to see if I had any factory .38 special ammo and I only found a couple of rounds. The OALs on them were very close to the OALs on the .357 mag factory rounds that I had -- closer than might be accounted for in the difference in the case lengths.

While looking up these numbers, I stumbled across an interesting bit of trivia concerning the .44 special vs .44 mag. It turns out that the SAAMI specs for the max OAL of the .44 special is actually slightly longer than for the .44 mag (i.e. 1.615" vs 1.610").