Light 357Magnum rounds

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Wildbillz

Wildbillz

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Hi All
I am getting ready to load up some 357Mag ammo. I am wanting to load them pretty light as they are just for plinking and such. Looking to stay around 1000 Fps or less. I have some 135grn TMJ Speer bullets that I am planning on using.

Can I use the 38Spl +P load data in a 357Mag case safely or should I go to the lowest 357Mag loading? If I do is there anything I need to be aware of?

Powder wise I have Hp-38, Unique, AA#5. Speer manual shows loads (38Sl +P) for the Unique and AA powders. I am still looking for something with the HP-38. Any reson to pick one of these over the other?

Thanks for your advice and help
WB
 
Wildbillz said:
Hi All
I am getting ready to load up some 357Mag ammo. I am wanting to load them pretty light as they are just for plinking and such. Looking to stay around 1000 Fps or less. I have some 135grn TMJ Speer bullets that I am planning on using.

Can I use the 38Spl +P load data in a 357Mag case safely or should I go to the lowest 357Mag loading? If I do is there anything I need to be aware of?

Powder wise I have Hp-38, Unique, AA#5. Speer manual shows loads (38Sl +P) for the Unique and AA powders. I am still looking for something with the HP-38. Any reson to pick one of these over the other?

Thanks for your advice and help
WB
Click to expand...
Well, the only real possible downside of using ANY .38Spl data in a .357Mag case is, you create a critical undercharge and potentially a situation where the powder swirls in the case and converts deflagration to detonation. Is that a real possibility? Yes. So is a local supernova. Is it a likely event? Nope. You would have to defy some pretty astronomical odds to undercharge a .357 case sufficiently to have a problem using high-pressure .38Spl loading data.

I think you’re safe using either mid-level .38+P or just under starting level .357Mag. They’re probably equal, come to think to it.

As for which powder, you’ve got three of the best for low-to-mid-level .357. I say go with the one you have the most of and can replace the easiest.
 
You can do a reverse load work up if your want to find out how low you can go. You don't run into problems till you start getting below 650 fps. This when the bullet does not clear the barrel, aka squib. You can safely use 38spl data start at max and go backwards. I have some loads using WST where I'm pushing a 158gr LSWC around 700 fps and lower. What you need to remember is that a Jacketed round takes more powder to move it down the bore. Lead is preferred since it's has less friction.

So using 38 spl data is not going to hurt anything. Just be aware that you can stick a bullet if you go too low.
 
I done a reverse ladder work up, loading .357 DOWN, to the point I could see the bullet IN FLIGHT. All the way down to sticking a bullet in the barrel, a 4.6" barrel.

I would point the barrel up before firing, to make sure the powder was against the primer.

4.0 gr of Unique should get you what you want. 3.5 gr is mild.
#5 is a great plinker powder.
HP-38 is very good and the most available, around here. Haven't seen Unique in 3 years.

Using .38 Spl data is safe, stay in the upper half. The longer .357 case will drop pressure. Be very aware that the bullet cleared the barrel, when shooting super light loads.

I increased powder charge to MY determined safe minimum and a 6 yo, who has never fired ANY gun, loved shooting it. His Mom did, too.
 
Better off using 38spl cases.
With light loads and fast powder just switching to a 38spl case nearly cut the standard deviation in half with a some loadings. If it was inconsistent shot to shot in 357 brass, switching to a 38spl case made it less terrible.
Unique will burn dirty if loaded lightly, I say don't waste the unique in low power ammo.
Unique is a great for full power or near full power 357 and hot 38spl in shorter and medium length guns.
I use HP38 in my 45acp silencer ammo at about a medium to upper loading on the load chart. I don't know how HP38 would like being lightly loaded and inside a huge 357 case. It would probably do better than unique.
I say load some up with HP38 and some more with AA5 and see which one is better.
 
There is not a lot of data out there for slow loads of light jacketed bullets in a .357. When I want to load light loads (often) I use plated bullets (Berry's) and lead bullet data. HP 38 works pretty well for light ,357 loads. I think the danger of using .38 jacketed bullet loads in the .357 case is maybe sticking a bullet. At least that is what this forum kept telling me a few years ago when I was still interested in light recoil jacketed loads.
 
Download grt for free and play with the numbers at no risk, until you find the load you want. I shoot a pile of 20k loads in 38 and 357 cases, but I don't shoot bullets that light. Unique would be easy to use because you are given a lot of data 38, 38+p and 357 data. Probably any load from 4.5-7.2 would work just swimmingly. 7 is a good light mag in a 158. Your charges will be higher because of the lighter bullet.
 
I use minimum charges of W231 and CFE Pistol with 357 cases and cast bullets sourced from Hodgdens web site. I think the data for HP38 is the same as W231. Both are accurate, but the CFEP load is moving faster.
 
I have used 38 Special data in 357 Magnum brass many, many times. Normally it will be with cast bullets and upper level 38 loads. Some have been max. 38 levels and some +P. The main consideration is to not load light 38 Special levels as too light and bullets can stick in the barrel.

FWIW; several times I have done the reverse, 357 Magnum data in 38 Special brass. I have/had waaay more 38 Spec. brass than 357 brass, and did so to conserve 347 brass. I know, "you might mistakenly put one in your 38 and put your eye out!" and of course warnings about the dreaded carbon ring. In 40 years of reloading I haven't had any problems mixing loads and I clean my revolvers after every range trip...
 
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.38 Spl +P loads work just fine in .357 Mag brass, you can always bump it up a tenth or two, but I load .357 Mag cases with WST or Competition pushing a plated or coated 158 Gr SWC to 700/750 FPS. 700X also works well, fast flake powders work the best for this.
 
Walkalong said:
.38 Spl +P loads work just fine in .357 Mag brass, you can always bump it up a tenth or two, but I load .357 Mag cases with WST or Competition pushing a plated or coated 158 Gr SWC to 700/750 FPS. 700X also works well, fast flake powders work the best for this.
Click to expand...
Yup. 3.5gr. of Bullseye under a 148gr. DEWC (seated to the case mouth) in a .357Mag case with a CCI No.500 primer used to be a real popular target/light hunting load for "standard" 4" .357Mag revolvers. My RBH 4-5/8" was good out to 30yds with that load and no hot powder spray.
 
To the OP:

Why plated bullets? If you are interested in LIGHT WEIGHT BULLETS, LOW RECOIL LOADINGS; lead bullets are available in much smaller sizes.

One of my favorite is a 95 gr LRN Powder Coated. Tried some 88 gr, but accuracy was unacceptable. The 102 gr and 105 gr are really good.

Try SnS or Eggleston. Look at the .380 bullets and get the .358 sized.
 
Seedy Character said:
To the OP:

Why plated bullets? If you are interested in LIGHT WEIGHT BULLETS, LOW RECOIL LOADINGS; lead bullets are available in much smaller sizes.

One of my favorite is a 95 gr LRN Powder Coated. Tried some 88 gr, but accuracy was unacceptable. The 102 gr and 105 gr are really good.

Try SnS or Eggleston. Look at the .380 bullets and get the .358 sized.
Click to expand...

To be honest, I bought 4K (Speer 135grn TMJ) of these a few years back and want to use them up. Not worried about going supper light (either in bullet weight or recoil) Most likely would be just fine in the lower to mid 357mag loading range. Like I said around 1000 Fps, maybe up to 1200 Fps or so. I want to be able to fire one to two hundred of them in an afternoon without it being to painful.

Thanks
WB
 
Add 10% to 38spcl load data when loading in 357mag cases and you’ll see very similar pressure results, with VERY SLIGHTLY increased velocity over the expected speed from the 38 load.

I have a couple loads of Unique & Bullseye under 93grn LRN’s and 125grn plated FP’s which truck out 650-800fps from 357mag brass. Ridiculously fun from a 7.5” Ruger Redhawk.
 
Slamfire said:
I wanted to create 38 Special equivalent loads in 357 cases, and I reported my testing in this thread:

.38spl vs 357 mag revolvers

You can download the 357 to 38 Special or +P 38 Special as long as you use the appropriate powders. Accurate Arms #5 was a real champ in this test.
Click to expand...
Yep, AA #5 did real well for me in .38 Spl +P, no reason it wouldn't do well in .357 Mag cases.
 
I’ve found Silhouette to work well in 38 Special. I’ve been tempted to try and make up a load in 357 but the absence of published loads is discouraging me.
 
Wildbillz said:
Hi All
I am getting ready to load up some 357Mag ammo. I am wanting to load them pretty light as they are just for plinking and such. Looking to stay around 1000 Fps or less. I have some 135grn TMJ Speer bullets that I am planning on using.

Can I use the 38Spl +P load data in a 357Mag case safely or should I go to the lowest 357Mag loading? If I do is there anything I need to be aware of?

Powder wise I have Hp-38, Unique, AA#5. Speer manual shows loads (38Sl +P) for the Unique and AA powders. I am still looking for something with the HP-38. Any reson to pick one of these over the other?

Thanks for your advice and help
WB
Click to expand...

You can use 38 Special +P data, but you will be loading them to low pressure and not necessarily low velocity. By definition, 38 Special is a lower pressure cartridge. It is not lower velocity by definition. The reason this is important is that you can load 357 Magnum cartridges to 40,000 psi, well within the CIP standard pressure for 357 Magnum, way, way over (double actually) the pressure limit for 38 Special +P, and still achieve a 1000 fps muzzle velocity. There are very good reasons to do this. Pressure is important to the ignition and burning of certain powders. Some powders need pressure or they will perform poorly. Allowing for higher pressure also enables you to use powders that you could not otherwise use to achieve your velocity goal. You will not get 1000 fps using a fast powder like Red Dot, Clays, N310 or Bullseye if your data is limiting you to 20,000 psi. Allowing for at least 35,000 psi (MAP for 357 Magnum under SAAMI) will enable you to create light loads with a greater variety of powders, many of which are available, less costly, and of which you can use far less per cartridge.

What I suggest is to consider loads near the top-end in velocity for 38 Special +P. Note that you will be using heavier charges of slower powders for these loads to achieve the velocity at low maximum average pressure. Also consider loads that for 357 Magnum that use fast powders. If you're not familiar with various powder burn rates, consult a powder burn rate chart or consider the velocity of the maximum published loads. The fast-burning powders will have a lower velocity for the maximum loads than the slow-burning powders.

What I would not do is use charge masses near the bottom of the published load data or reduced from the published load data, except to work up from. If you're achieving your velocity goal with a "reduced" charge, then you will probably be better off using a faster powder.
 
Of the powders listed, I would recommend using HP-38. The other are much slower than needed. You provided a desired velocity, but did not give any gun info. Note that Quickload barrel length is breech to muzzle. Also subtract about 50 fps for cylinder gap.

Code: 
Cartridge          : .357 Magnum (SAAMI)
Bullet             : .355, 130, Speer TMJ 4010
Seating Depth      : .322 inch
Cartridge O.A.L. L6: 1.590 inch = 40.39 mm
Barrel Length      : 5.5 inch = 139.7 mm
Powder             : Hodgdon HP38

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms
-28.6   30     4.00    855     211   11031   2908     99.4    0.855
-25.0   31     4.20    886     227   11965   3041     99.8    0.822
-21.4   33     4.40    916     242   12941   3166    100.0    0.793
-17.9   34     4.60    946     258   13960   3284    100.0    0.766
-14.3   36     4.80    974     274   15021   3401    100.0    0.740
-10.7   37     5.00   1002     290   16124   3517    100.0    0.717
-07.1   39     5.20   1028     305   17271   3633    100.0    0.695
-03.6   40     5.40   1055     321   18462   3749    100.0    0.674
+00.0   42     5.60   1080     337   19697   3865    100.0    0.655
+03.6   43     5.80   1105     353   20976   3980    100.0    0.637
+07.1   45     6.00   1130     368   22301   4095    100.0    0.619
+10.7   46     6.20   1154     384   23672   4209    100.0    0.602
+14.3   48     6.40   1177     400   25088   4323    100.0    0.585
+17.9   49     6.60   1201     416   26553   4437    100.0    0.570
 
derek45 said:
5.0gr win 231 / HP38
Click to expand...

Just an old guy here. I load 5.0 grn 231, mag primer, .357 case behind 158 grn RNFP Bear Creek moly coated pill. Seat deep with a taper crimp just over the ogive so not to mar the pill, COAL 1.510". Got it cronoed once 5 rounds 910 to 925 fps. 3 round groups @ 25 yds .75" and play hell with a 6" steel @ a little over 70 yds with a stock triggered 6" GP100 topped with a red dot. Not too bad for 3\4 of a century on this planet. You can shoot this one all day long... Sight height 1 3\4", zero 1 1\4" high @ 25 yds and you can hold on out to about 75 yds. I love it when a plan works!!!
HAVE FUN!!!
Edit - all cases trimmed 1.280".
 
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So I loaded some up and finely got out to test fire them the other day. I loaded with AA#9, AA#5, 2400, Unique and Power Pistol. Recoil wise I liked the load with the AA#5 (38Spl +P Load data). Super easy to shoot and light recoil. Next would be the Unique loading and then the Power pistol (Both from Speers 357Mag loadings at the low end. The others were more blast and recoil then I was looking for.. So I will move forward with the three I liked and see if I can find a load that works out for me accuracy wise as well.

Thanks
WB
 
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