using 357 brass for light target loads

The difference between 38 and 357 is the case length and the maximum average pressure limit. The brass and chamber length determine the maximum case length that can be used. A 357 revolver has a cylinder that is manufactured and proof tested to allow higher pressures.

Low recoil loads are achieved with lighter bullets and lower velocities. That's it. The case length and pressure limit alone do not necessarily affect recoil, and so there is no difference between 38 and 357 in terms of recoil unless the case length and higher MAP limit are used to propel heavier bullets or bullets to higher velocities.

The case length's affect on potential powder volume affects velocity two ways. The first is because a greater amount of energy requires a greater volume of powder. Second, in order to get even more energy into the cartridge without exceeding the maximum average pressure limit, a volume of deterrent is needed to make the powder burn slower and more progressively.

Pressure does have an effect on velocity, but only over time. Higher pressure does not necessarily result in higher velocity if it is over a shorter period of time. Higher velocity can be achieved with low pressure provided the pressure is maintained over a longer period.

Seating depth affects pressure and the longer case length can affect seating depth. Let me define seating depth in terms of what really matters: the initial combustion chamber volume. The best way to calculate the adjustment needed to maintain a certain pressure level with changes in initial combustion chamber volume is to use a model like that in Quick Load. If the loads are near minimum pressure, they may need to be adjusted if the initial combustion chamber volume is increased due to a longer case length. Minimum pressure loads can be avoided without necessarily increasing velocity by using a faster burning powder. If the 38 loads are near the minimum pressure, instead of increasing the mass of Bullseye slightly, use Clays or Red Dot instead to get pressures up to safe levels without increasing velocity. Bullseye is already a pretty fast powder, so I doubt there is a need to load it at minimum pressures.

The 38 Special load consisting of a Speer 148 grain LHBWC over 3 grains of Bullseye with a COAL of 1.150 is calculated to produce 16158 psi MAP. Putting that same load in a 357 case with a COAL of 1.29 results in only 11954 psi. Increasing the charge mass by 10% to 3.3 grains results in 14280 psi. In this case, it is calculated to take more than 17% greater powder mass to obtain the same pressure with the longer 357 case.

There are reasons not to use low pressure. Bullseye is position sensitive and a low case fill will produce inconsistent results. You could try to use a load with higher pressure, but the LHBWC is not the best bullet for higher pressures and velocities.

Look at this data for Bullseye with the 158 grain SWC: https://reloadingdata.speer.com/downloads/speer/reloading-pdfs/handgun/357_Magnum_158_LSWC.pdf

I recommend 158 grain JHP even more, but load data for that type of bullet rarely includes Bullseye powder. That isn't to say it won't work great, it's just that more people will prefer to use Unique for this. I use HP-38 and Titegroup (both similar to Bullseye) with 158 grain JHP and they are very good. You might be able to load somewhere between 6 and 6.6 grains of Bullseye under a 158 grain JHP.

The real danger with any of these loads is the possibility of a double-charge. If you get away from the full wadcutters and start seating bullets only part way into the case, you will leave a lot of case volume that can hold a double-charge. With SWC or JHP, it's safer to use a bulkier powder than Bullseye. Trailboss would be ideal, or Tin Star, but alas. Unique and Universal will work.
 
Been loading 38 special loads in 357 cases for a few years. For lead bullets, particularly HBWC's, you may have to up the powder charge a couple of tenths of a grain so that the base/skirt will expand to seal or you could have some leading or a squib. My Security Six needed the slight bit of extra powder, my Colt did not. The Colt barrel is a little tighter than the Ruger. YMMV. I just did it so I could leave my dies set for everything but wad cutters.
 
I’ve seen folks suggest using 38 special data and increasing the powder charge 10% for the 357 case. I’ve never done it, but you could always just use 38 special data and work up a little bit. You may like the 38 special data in 357 case, but it will be less velocity all other things equal.
That works! In fact, adding 10% to a .38 Special +P load will most times be lower than 357 starting loads. Another trick used for decades is adding a tenth or two of a grain of powder to give about the same velocity and pressure from the larger 357 case. I have heard that loading to 15,000 psi will result in a cleaner burn with powders like Unique, and maybe others. :) My go-to load for decades for 357 has been 5.5 gr. Unique, standard primers, 860 fps chrono'ed from a 4" barrel. 38 +P max, depending who you ask, is 5.2-6.0 gr.
 
Yep, just adjust the dies for the longer Mag cases, might need another tenth or two of powder. I shoot light target loads in .357 Mag brass all the time, I never use .38 Spl cases in .357 Mag revolvers, not that there is anything wrong with that, there isn't.
I'm in the "have thousands of 38 cases loaded up but shoot all 357 mag revolvers" school. Otherwise, me too! Lol.
 
I do not like cleaning out the lead ring that develops in 357 Magnum cylinders after shooting 38 Special loads. I once shot a case of +P Zero 158 LSWC HP bullets through my M66 S&W, and those swaged bullets left a tall lead ring that was very hard to remove. If I fired 357 rounds in that cylinder, the lead ring would anchor the fired round and that made extraction difficult.

I decided to test three powders, Unique, Bullseye and AA#5. All of these powder do outstandingly in the 38 Special case, and there is no reason for them not to do outstandingly in the slightly longer 357 Magnum case. I wanted fast powders, slow powders (2400, AA#9, H110) are inappropriate in this velocity range. My velocity goal was 760 fps with a 158 grain lead bullet. I came up with this number decades ago after chronographing factory 38 Special. I have shot tens of thousands of 38 Special loads loaded with 158 lead bullets, 3.5 grains Bullseye, any case, any primer. It shoots to point of aim in all my fixed sight vintage revolvers, does not lead the barrel, does not beat me or the revolver up. And is accurate out to 50 yards. Based on reloading manuals, articles, etc, I have no issue with a 800 fps load in a 357 Magnum. In fact some of what I read, the 38 Special was factory loaded in the 800 fps range.

All of my reloads were accurate, shot well. Slight differences in elevation, not sure if it was me, or the round. I was surprised on how well AA#5 did, I never shot any Unique 38 Special loads, but it shoots well. My standby is with Bullseye Pistol powder, and it does very well.


Colt Trooper MKIII 6" Barrel


158 LSWC Factory Zero 38 Special ammunition
13-Sep-18 T = 72 ° F

Ave Vel = 739
Std Dev =38
ES = 152.4
High = 804.1
Low = 651.6
N = 18

158 LSWC Factory Hornady 38 Special ammunition, box dated 12-1982
13-Sep-18 T = 90 ° F

Ave Vel = 734
Std Dev = 16
ES = 50.56
High = 755.8
Low = 705.3
N = 16



158 gr LRN 3.5 grs Bullseye 38 SPL cases WSP
13-Sep-18 T = 72 ° F

Ave Vel =764
Std Dev =24
ES = 87.45
High = 804.1
Low = 716.6
N = 21


158 gr Valiant LRN 3.8 grs Bullseye lot 907 6/20/05
once fired mixed 357 cases, WSP

19-Sep-18 T = 80 ° F

Ave Vel =788
Std Dev =38
ES = 147.4
High = 830.3
Low = 682.8
N = 25

accurate no leading

HB3hyQK.jpg


158 gr Valiant LRN 4.0 grs Bullseye lot 907 6/20/05
once fired mixed 357 cases, WSP

19-Sep-18 T = 80 ° F

Ave Vel =800
Std Dev =26
ES = 102
High = 846.2
Low = 744.2
N = 24

very accurate, no leading


WpnNgAO.jpg


158 gr Valiant LRN 4.0 grs Bullseye lot 907 6/20/05
357 Midway cases, WSP

11-Oct-18 T = 71 ° F

Ave Vel =817
Std Dev =23
ES = 72.55
High = 853.6
Low = 781.1
N = 12

158 gr Valiant LRN 4.5 grs Unique lot 364 3/9/1992
Midway 357 cases WSP

13-Sep-18 T = 72 ° F

Ave Vel = 815
Std Dev = 26
ES = 106.7
High = 853.5
Low = 746.8
N = 18

Low recoil, about 2" above point aim, accurate, low noise

OuqSBBO.jpg


158 gr Valiant LRN 5.0 grs Unique lot 364 3/9/1992
R-P 357 cases WSP

13-Sep-18 T = 72 ° F

Ave Vel = 852
Std Dev = 22
ES = 85.04
High = 891.4
Low = 806.4
N = 24

increased recoil, about 2" above point aim, accurate, louder

mT6vlv0.jpg



158 gr Valiant LRN 5.5grs Unique lot 364 3/9/1992
R-P 357 cases WSP

13-Sep-18 T = 72 ° F

Ave Vel = 919
Std Dev = 32
ES = 117.2
High = 972.1
Low = 854.9
N = 24
shot close to point of aim, much louder, more recoil, some leading
DQsERVT.jpg



VTtDI0h.jpg





M66-2 4" Barrel

158 gr LRN 3.5 grs Bullseye 38 SPL cases WSP
13-Sep-18 T = 88 ° F

Ave Vel = 726
Std Dev = 24
ES = 74.42
High = 765.5
Low = 691
N = 21


158 LSWC Factory Zero 38 Special ammunition
13-Sep-18 T = 88° F

Ave Vel = 723
Std Dev = 28
ES = 102.2
High = 761.7
Low = 659.4
N = 22


158 Hornady XTP 7.4 grs AA#5 Lot DM loaded 6/3/1993
38 Special cases, WSP, OAL 1.460"

13-Sep-18 T = 88 ° F

Ave Vel = 894
Std Dev = 54
ES = 166.4
High = 956
Low = 789.5
N = 16

158 gr Valiant LRN 4.5 grs Unique lot 364 3/9/1992
Midway 357 cases WSP

13-Sep-18 T = 88 ° F

Ave Vel = 780
Std Dev = 23
ES = 81.02
High = 819.1
Low = 738.1
N = 17


158 gr Valiant LRN 5.0 grs Unique lot 364 3/9/1992
R-P 357 cases WSP

13-Sep-18 T = 88 ° F

Ave Vel = 821
Std Dev = 40
ES = 123.8
High = 900.5
Low = 776.7
N = 24


158 gr Valiant LRN 5.5grs Unique lot 364 3/9/1992
R-P 357 cases WSP

13-Sep-18 T = 88 ° F

Ave Vel = 894
Std Dev = 18
ES = 62.65
High = 923.7
Low = 861.2
N = 26

PkVDLQq.jpg


WMwE5NW.jpg
 
I found a few powders that were common to 38+p data and 357 Magnum data. I tried loads that were about halfway between 38 +p max and 357 Mag min. There is a gap between them. Worked fine in my S&W 19-4 that was not the gun I would choose for full power loads like my 586-1M.
6.4 BE-86 158 lead
6.3 Power Pistol 180 XTP
7.3 HS-6 158 XTP
 
Took the Colt Trooper out, shot one handed, Bullseye Style at 50 yards with the thing, and a load of 158 LRN 6.0 grs AA#5, WSP and 357 Magnum cases. Low recoil but good accuracy. Target is 24" X 18". Twenty four shots, 24 hits.

First round of that load landed almost perfect dead center. It was luck.
 

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Took the Colt Trooper out, shot one handed, Bullseye Style at 50 yards with the thing, and a load of 158 LRN 6.0 grs AA#5, WSP and 357 Magnum cases. Low recoil but good accuracy. Target is 24" X 18". Twenty four shots, 24 hits.

First round of that load landed almost perfect dead center. It was luck.
When I bought my 4” Lawman I was actually looking for a Trooper. The supervisor at Piper I was working for called them a working man’s Python. The shop I went to was owned by a former AF MSG who cut me a great deal but he couldn’t get a Trooper. I took the Lawman and have never regretted it. Several promotions and bonuses, a career change and a family later and I did eventually get both a 4” and 6” Trooper, plus a 2-1/2” Lawman, and I went through quite a few Pythons - I still have the 4” Lawman from the mid 80’s and a 6” Python. The rest are history.
 
One of the things I have learned over the years a Cast Bullet 140 grains or lighter does better in a 38 special case than in a 357 magnum case, when using light loads. In the shorter case I always get a full burn of the powder, sometimes that does not happen case with the longer case.

That's my story your mileage may very. :)
 
So I loaded up some Berry's 148g DEWC in 357 brass, seated near flush.

I used my loads from 38 spcl, just stuck with them. I ran them through my 6" Python, chrono at 9'. As always, this is my load data, use with caution.

3.3g Bullseye and 3.5g of HP-38 both ran in the 750 fps range. Accuracy was so-so.

As I've found that those Berry's run better a little bit hotter, I'm kicking around adding around 10% to both of those charges, taking the BE to 3.6g, and the HP38 to 3.8g.
 
I have several revolvers chambered in 38 Special so I save 38 Special cases for them and use only 357 Magnum cases in the 357 Magnum revolvers.

I shoot mostly mid-range 357 Magnum loads these days. A 158 grain cast SWC bullet over Unique that yields about 950-1000 fps in a 4" revolver.

A top 38 Special load in a 357 Magnum case would be a good mid range load as well.
 
I haven't owned a 38 special revolver since the '70's when I moved to 357. I have been loading light 38 special loads in 357 brass all those years and never have had a problem. I cast my own bullets and now size them with a Lee sizer, powder coat them, and resize. Bore leading has gone completely away. I can't remember ever haven't to throw any brass away as it just lasts and lasts.
 
I used 9.4 gr. Blue Dot with 158 gr. Lead SWC with satisfaction before the warning about it and 125 gr. bullets. It's a good powder, and if/when I can find it again, I'll buy some.
I run 10.6 with a cast 156 and like it just fine. I'm saving mine for 45-70 because 19.0 makes a great load and I only have 1.5 pounds left....
 
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