Using 38 loads in 357 cases

[parabarbarian]

I recently loaded 100 rounds of Berry's 158 gr FP in 357 cases. Fifty had 6.0 gr of Unique and the other 50 held 6.0 gr of Power Pistol. I compared these to 38 spl cases loaded with the same bullet and 6.0 gr of PP. When I examined the cases it looked to me that, judging from primer condition, the pressures in the 357 cases for both powders was lower than the pressures in the 38 cases. I wasn't able to set up a chronograph that day so I don't know how velocities compared.

Has anyone else noticed something like this? I would not have thought that a 0.135" extra case length would make that much difference.

 

[OKFC05]

It's called expansion ratio,and yes it does make a difference.
The smaller the volume under the bullet, and the heavier the bullet, the greater the containment,which is a major factor in pressure produced. Think about it, if you burn the powder in the open with no containment, there is no pressure.

You can compare similar loads in .38 and .357 cases using manufacturers data.
http://data.hodgdon.com/main_menu.asp

 

[Alk8944]

I would not have thought that a 0.135" extra case length would make that much difference.

It isn't directly the .135", it is how it affects the total case volume under the bullet and the effect this has on loading density. To get the same velocity in a .357 case as in .38 Special with everything else equal, seating depth, bullet weight and type, and same powder, the charge needs to be increased approximately 13-15%. To get the same velocity as 6 gr/Unique in a .38 case the charge needs to be ca. 6.9 gr. in the .357 brass.

 

[smokinwoody]

I can tell you what I have done in the past...

I use to shoot .38 special in my .357's...well we all know that the cylinders need that extra scrubbing from the shorter case..I was using 5.1 grs of W231 with 158gr LSWC's..we figured around 850fps with this load..

I hate cleaning guns..especialy where I realy dont need that extra scrubbing..time consuming..so..I loaded my .357 case with 5.8grs of W231 with the same 158gr LSWC and guess what..just a tad over 1,000fps, accurate as all hell and I get to clean less..

 

[parabarbarian]

OK, I can see the point. The extra length increase the volume by about 12%. Since the powder is a propellant not an explosive the pressures are proportionally less. I see that Speer #9 has 6.5 gr of Unique as starting load for a 158 gr lead SWC. I guess that should be my next step.

That also implies that if 4.0 gr of Unique works well for the 148 gr DEWC in a 38 spl case, a 357 case needs something like 4.5 gr.

 

[nightshade2x]

Am I off in thinking 6.0 Gr. of Unique as a .38 Spl. loading for a 158 gr'er is a bit hot?

Have fun and be safe.
Nightshade2x

 

[BigBill]

I found out if we use the same load for the swc leadcast in the 38special we get better ballastics than the same load in the 357mag. Its the longer empty magnum case that causes this. I notice with some of the powder charges the magnum case is only half full so its less pressure. Becareful with the lighter loads in the larger cases too. Some gun powders don't like the empty space in the cases. I can't remember the powder that was used but the gun blew up because the powder charge was too light. This happened many years ago in one of the gun rags it was talked about. Bill

 

[5906fan]

my favorite 'plinking' load is 4gr Red Dot under 158gr Lee mold cast and quenched w/w's put up in .357 cases, standard primers. basically a .38+P load
accurate and has some 'pop' to it also.

 

[smokinwoody]

I found out if we use the same load for the swc leadcast in the 38special we get better ballastics than the same load in the 357mag. Its the longer empty magnum case that causes this. I notice with some of the powder charges the magnum case is only half full so its less pressure. Becareful with the lighter loads in the larger cases too. Some gun powders don't like the empty space in the cases. I can't remember the powder that was used but the gun blew up because the powder charge was too light. This happened many years ago in one of the gun rags it was talked about. Bill

I agree...

that can happen easily with rifle loads..must watch the powder thats used and always read the manufacturers suggested loads...I always cross reference with the many loading manuals that I have and read magazine articles ..

all powders are obviously not equal and all have different burn rates..some, like W231 will allow 5.8grs and a bit more in a .357 case and be considered a light magnum load.. where in a .38 5.2-5.4grs would be considered HOT with the same 158gr bullet...

I have split cases...those were .38 Special's....

live and learn...be safe and have fun...

 

[parabarbarian]

Am I off in thinking 6.0 Gr. of Unique as a .38 Spl. loading for a 158 gr'er is a bit hot?

It is. The 6.0 gr of Unique was in the 357 cases. I also loaded some with 6.0 gr of Power Pistol -- a max 38 spl load -- in both 38 and 357 cases for comparison.

I hate cleaning guns..especialy where I realy dont need that extra scrubbing..time consuming..so..I loaded my .357 case with 5.8grs of W231 with the same 158gr LSWC and guess what..just a tad over 1,000fps, accurate as all hell and I get to clean less..

That's in the ball park of what I'm aiming for. I'm trying to find a good load that generates 1,000 to 1,100 fps with a 158 or 1,100+ fps with a 148 gr bullet. Since I can reload the longer cases for a fraction of penny more why not shoot what the gun was made for? My experience is that a 357 revolver is a bit more accurate with the longer cases. I still reload the 38 cases and will continue to do so unless I trade them off for 357.

 

[longr]

I found out if we use the same load for the swc leadcast in the 38special we get better ballastics than the same load in the 357mag. Its the longer empty magnum case that causes this. I notice with some of the powder charges the magnum case is only half full so its less pressure. Becareful with the lighter loads in the larger cases too. Some gun powders don't like the empty space in the cases. I can't remember the powder that was used but the gun blew up because the powder charge was too light. This happened many years ago in one of the gun rags it was talked about. Bill

I remember reading stuff that too. I think the problem happened when using slow burning powders in large rifle cases because the pressure spiked too quickly instead of building "slowly".

 

[Nick B]

I can tell you what I have done in the past...

I use to shoot .38 special in my .357's...well we all know that the cylinders need that extra scrubbing from the shorter case..I was using 5.1 grs of W231 with 158gr LSWC's..we figured around 850fps with this load..

I hate cleaning guns..especialy where I realy dont need that extra scrubbing..time consuming..so..I loaded my .357 case with 5.8grs of W231 with the same 158gr LSWC and guess what..just a tad over 1,000fps, accurate as all hell and I get to clean less..

Have you ever chronographed that 5.8 grain load ?

 

[smokinwoody]

was already done...its a published load..same gun..

 

[BigBill]

I think the problem was with a lighter load in a handgun case using bullseye powder. They went way too light with the powder charge. Bill

 

[bmcgilvray]

I like 5.0 grains of Unique and a 158 grain cast lead SWC bullet put up in a .357 Magnum case for mild shooting. Clocks 933 fps from my 6-inch Smith & Wesson Model 27. This is more my notion of a ".38 Special" load in a .357 Magnum case.