Author Topic: 357 magnum load data question  (Read 3115 times)

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mikefamig

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Re: 357 magnum load data question
« Reply #15 on: January 16, 2021, 08:01:58 am »
Mike
Your Question: I don't recall ever loading 7 grains of Bullseye for The 158 gr LSWC in 357 mag, I think that would be a little to hot.  Never had to get to 7 grs.
When developing a load for 357 mag using Bullseye I normally start with the suggested start load in "Alliant Powder reloading guide" and work up.
4.8 gr of Bullseye behind Your 158 LSWC should give a velocity of around 940 feet in a 6 inch barrel. Use Your 5 gr powder slide, load a dozen and give them a try. check for over pressure signs, check for leading, leading near the forcing cone  will indicate you need to increase the amount of powder, leading near the muzzle indicates high pressure. and then start tweeking the powder charge for accuracy.
I bought My first Star loader in 1956 "still have it" and a few more.

Good Shooting

Lindy

Lindy

Thanks again for the reply. I called Alliant and actually got a call back from a human being. I was told that the 4.8 grains recommended on the web site is the maximum load. It's amazing to me that the web site just puts the number out there without saying if it is a starting point or maximum so I got that cleared up.

When I pointed out to him that the Lee manual stated that you could load between 5.8 and 6.5 he explained that it is because they are testing with a harder bullet. Alliant is a sister company to Speer so Alliant load data is for use with Speer lead bullets.

I learned that higher pressures are needed to obturate a harder bullet and that Lee must be testing with a harder bullet than Alliant. I bought stateline bullets and they are BHN 16 which is a relatively hard lead bullet so I'll be wanting a moderate to high pressure load.

To sum it up I think that you are correct to start with the 5 grain load and see how that goes. I loaded some 38 special with the 2.7 charge bar which is dropping more like 3.8 and 3.9 Bullseye and I have not seen any leading but I did not look closely. I'll have to have a close look at those guns.

Thanks again, Mike.

mikefamig

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Re: 357 magnum load data question
« Reply #16 on: January 16, 2021, 08:18:41 am »
I also have a 3.5 grain Bullseye charge bar and will load a couple of them.

I also did some research on Trail Boss powder and found this at imrpowder.com.

If you don't see Trail Boss data for your favorite cartridge we have a formula for developing loads for all cartridges and it's simple to follow.  This formula may be used in both rifle and pistol applications:

Find where the base of the bullet to be loaded is located in the case and make a mark on the outside of the case at this location.  Then fill the case to that mark with Trail Boss, pour into the scale pan and weigh.  This is your maximum load.  Pressures will be below the maximum allowed for this cartridge and perfectly safe to use!Take 70% of this powder charge weight (multiply the maximum load from step 1 by .7), and that is your starting load.Start with this beginning load and work up to your maximum charge, all the while searching for the most accurate reduced load.  Once found, the fun begins!''



I did this test and found that the 357 magnum casing held about 5.3 grains of Trail Boss which bothered me becasue the IMR web site calls for a maximum load of 4.2 grains not 5.3. I then filled a 38 special casing and found that it did hold about 4.2 grains of powder which is the same as the maximum recommended for 357 magnum. Then it occurred to me to look at the web site for the maximum load for the 38 special and it was the same as the maximum for the 357 magnum (4.2).

I do not know why they have the same maximum load for both 38 spc and 357 magnum but if you can believe the above procedure then the maximum for the 357 is more like 5.2 than 4.2 for Trail Boss powder.

Mike.
« Last Edit: January 16, 2021, 08:51:21 am by mikefamig »

mikefamig

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Re: 357 magnum load data question
« Reply #17 on: January 29, 2021, 09:25:16 pm »
After all of the time that I spent trying to come up with a good recipe for hard cast lead bullets in a 357 magnum I decided to not use the bullseye powder and instead go with 3.8 to 4.2 grains of Trail Boss powder with a 158 grain lswc.

 I understand that there are many tried and true combinations of powder and bullet that I can use but supplies are not available at any price right now so I am restricted to using the powders and bullets that I have on hand which is Bullseye, Trail Boss and hard cast lead bullets. ~16 BHN.

I used a vernier caliper to measure how much powder fits in the case and 4.2 will give me a nice safe load. I used a charge bar that is made for a large load of 2400 powder and made shims in the lathe to meter 3.8 and 4.2 grains of TE.

 Alliant doesn't recommend that you use Bullseye with a bare lead bullet and that bothers me so Trail Boss it is.

Mike.
« Last Edit: January 29, 2021, 09:56:26 pm by mikefamig »