Reloading .357 mag

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  • Last Post 12 January 2012
paperpuncher10 posted this 12 January 2010

I have SP Mag primers to use up and would like to load .357 brass at .38 +p levels.  I shoot a Ruger GP100 4".  I have Unique, Bullseye and 2400 powder on hand.  Does anyone have a proven safe loading for the above components?  If so, please share.

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RicinYakima posted this 12 January 2010

Yes, I do, but what bullets are you planning on using? Ric

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paperpuncher10 posted this 12 January 2010

158gr LSWC by Oregon Trail.

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Tazman1602 posted this 13 January 2010

I just loaded and shot some of those today only I have no SP mag primers left so these were SP standard primers. Load manual (Lee) start load of 6.2grs of Unique was very pleasant to shoot with my 158gr cast RF. No idea of accuracy yet.

2400 would actually be a better powder and Lee load manual says 13.9 start load and Lyman manual says 11.4 for a start load.

If you do't have a load manual you need at least two IMHO.

Nothing wrong with Unique though!

Art

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paperpuncher10 posted this 13 January 2010

Thnks Tazman, I have a Lee load manual and have seen those loads.  They are hotter than the .38sp +p.  I understand I can subtract .6 or .7 gr of powder and use the Mag primers.  I am concerned however about dropping to many fps and sticking a slug in the barrel .  I would like to drop to about 900 fps and start adjusting for accuracy.

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Tazman1602 posted this 13 January 2010

I just checked for you and the Lyman Cast bullet manual load of 11.4grs of 2400 lists at 1024fps which is close to where you want to go. However, I'd suggest you don't go below that until you know a lot more than I do, I always stick to the listed loads unless I know what I'm doing. With rifles and jacketed I know what I am doing. With rifles and cast I know what I'm doing. With pistols/revolvers and cast I am a dog gone neophyte....

If you don't shove the bullet out hard enough it can cause leading the same way as if you shove it out too hard..........don't ask how I know that one or why I stick with the listed loads now...........<GRIN>

Glad I have Unique because 2400 doesn't exist in my area and those haz-mat fees are killer................

Art

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RicinYakima posted this 13 January 2010

paperpuncher10,

First off, check to see how much too small the OT bullets are for your cylinder. Drop a bullet into the cylinder and if it falls out the front, you will have to deal with the leading issue. OT's are know to be sized very small and are way to hard for the velocity you are looking for. Some times you can fix this by coating the bullets with Lee Liquid Alox on top of the factory lube, before loading, just let it dry well.

Alliant now, for the last 10 years, has only recommended SP Mag primers for 357 loads with 2400, so any recent data is with Mag primers. But, this isn't the best powder for 900 f/s loads. Nor with small hard bullets are you going to be leading free.

I have shot a lot of 4.5 grains of Bullseye from a 357 Martini rifle loaded with small rifle primers. But it is only going about 1050 f/s from a 25 inch barrel and may be less than the speed you are wanting to reach.

Unique seems to be your best bet. Alliant has load data for two 158 grain bullets on their web site. 4.5 grains at 850 to 6 grains at 1100 seems to be the range. With Mag primers, I would consider starting at 4.5 grains and working up until you get un-acceptable leading, your velocity goal or acccuracy level.

HTH, Ric

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paperpuncher10 posted this 13 January 2010

Thanks for good info.

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Ed Harris posted this 27 January 2010

5 grains of SR7625 with NEI #161A in .357 case is 1030 f.p.s. from Marlin, very quiet and accurate.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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paperpuncher10 posted this 27 January 2010

Thanks Ed!

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gunarea posted this 28 January 2010

Hey Puncher

     Save your mag primers for use with a suitable powder combination. The hotter primer will cause pressure and velocity variations. That in turn will make the load produce large shot groups and seem inaccurate. We all know how rotten that can be.

                                                                                      Roy

Shoot often, Shoot well

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Caster4life posted this 10 January 2012

If you don't have a reloading manual, go online to castpics.com. It has 3 old reloading manuals, and almost 400 pages of cast bullet reloading info...found it recently and thought it was great

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Ed Harris posted this 11 January 2012

Some chronograph data from the Back Creek Diary:

Ruger SP101 2” .38 Spl.

NEI#161A 188-gr.WW, OAL 1.55” Fed. Cases, Fed 100 3.5 Bullseye, 706 fps, 8 Sd 10.0 #2400, 933 fps, 15 Sd

Colt 6” Officer's Model .38 Spl. NEI #161A as above 1.55” OAL 3.5 Bullseye, 751, 18 Sd 10.0 #2400, 1102, 20 Sd

Marlin 1894 Cowboy II, 24” bbl. NEI #161A as above 1.55” OAL 3.5 Bullseye 905 fps, 4 Sd 10.0 #2400 1369 fps, 11 Sd

The above all in .38 Special brass. For a medium velocity load in .357 Magnum cases with 158-160 grain bullets at 1.58” OAL use these as minimum start loads and OK to increase a grain or so as needed to get best accuracy. I use 4.2 grs. of Bullseye alot as a light .357 load and use 11 grs. of #2400 with SP Magnum primers with satisfactory results, because this charge is well below maximum. Speer no longer recommends using magnum primers with #2400 in the .357.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Will Durant posted this 12 January 2012

With a good cast 158 I have used 6.5 grains of Unique for over 25 years.Works great.Will

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