Reloading for the .357 Magnum - The Firearms Forum

neilin · 02-10-2009, 04:40 PM

The .357 Magnum cartrigde is one that I have little experience reloading. I recently purchased a Ruger GP100, and I have reloaded 50 rounds using 6.5 grains of Unique with a 158 grain LSWC bullet and small pistol magnum primer. My first question is: Would it be okay to use the small pistol primer instead of the small pistol magnum primer? My second question is: Using the .357 case, Unique powder, and 158 grain LSWC bullet, would it be okay to load the longer .357 case to .38 Special specifications? Thanks!

justdoit · 02-10-2009, 05:49 PM

neilin, your load sounds ok but the magnum primers will up the pressure, you should use regular small primers with this load.
as far as loading 357mag to 38spl specs, i don't think this would be good because there is about 2gr different in these loads, could cause a squib.

army mp · 02-11-2009, 06:52 AM

there is a trick to loading lead. and if you go to fast or to slow with your bullets, you will get leading in the Barrel. and it can damage a good gun fast, saying that becarefull where you get your Bullets. I have picked up Lead bullets at Gun shows , tested them on a Seaco hardness tester. and they have Been all over the place. Most cast load books are for Lyman #2. a little harder than clip on wheel weights. but a lot of guys are throwing the stick on weights in and they are just over pure lead. a good test if you have a good scale . say if you are shooting a 158Gr. bullets the The more the bullet weighs 159Gr, 160Gr, the higher the lead content. inturn the softer the bullet. pushing to hard a bullet to slow will lead as will pushing to soft a bullet to fast. I cast my own bullets and heat treat them, but I still never go over 900 FPS unless Gas checked

LDBennett · 02-11-2009, 07:02 AM

neilin:

Use the primers called out in the reloading recipe in the manual you got the load data from. If it isn't in a manual (or in the manufacturer's online load data) then don't use the modified recipe. Use the recipe as listed there.

Most reloading manuals have reduced loads data for approaching the 38 special levels. Again, find the load you want in a manual and use it exactly as shown. Arbitrarily lowering the load level from a manual below the starting load CAN be dangerous as too much air space in a cartridge can be as bad or worse than too much powder (detonation).

Also the more air space in the cartridge the more varible the ignition can be dependent on how the powder lays in the cartridge in the gun when it is fired. Huge difference can occur in the pressures from the powder being all the way to the rear to all the way forward. The most repeatable loads often are the ones that are closer to filling the case, unless the powder has been designed to work equally well where ever it is inside the cartridge. Powders like W231 or Hodgdon HP38 or other fast powders that use small quantities are usually designed for small quantities of powder in the case whereas Unique and others MAY not be.

So, follow the published recipes exactly as shown to stay safe.

LDBennett

02-10-2009, 04:40 PM	#1
neilin V.I.P. Member Join Date: Jan 2009 Location: Clinton, MO Posts: 116	Reloading for the .357 Magnum The .357 Magnum cartrigde is one that I have little experience reloading. I recently purchased a Ruger GP100, and I have reloaded 50 rounds using 6.5 grains of Unique with a 158 grain LSWC bullet and small pistol magnum primer. My first question is: Would it be okay to use the small pistol primer instead of the small pistol magnum primer? My second question is: Using the .357 case, Unique powder, and 158 grain LSWC bullet, would it be okay to load the longer .357 case to .38 Special specifications? Thanks! -->

02-11-2009, 06:52 AM	#3
army mp V.I.P. Member Join Date: Jan 2009 Location: western Pa, Posts: 479	Re: Reloading for the .357 Magnum there is a trick to loading lead. and if you go to fast or to slow with your bullets, you will get leading in the Barrel. and it can damage a good gun fast, saying that becarefull where you get your Bullets. I have picked up Lead bullets at Gun shows , tested them on a Seaco hardness tester. and they have Been all over the place. Most cast load books are for Lyman #2. a little harder than clip on wheel weights. but a lot of guys are throwing the stick on weights in and they are just over pure lead. a good test if you have a good scale . say if you are shooting a 158Gr. bullets the The more the bullet weighs 159Gr, 160Gr, the higher the lead content. inturn the softer the bullet. pushing to hard a bullet to slow will lead as will pushing to soft a bullet to fast. I cast my own bullets and heat treat them, but I still never go over 900 FPS unless Gas checked

02-11-2009, 07:02 AM	#4
LDBennett Advanced Senior Member Join Date: Dec 2003 Location: Hesperia, CA Posts: 5,711	Re: Reloading for the .357 Magnum neilin: Use the primers called out in the reloading recipe in the manual you got the load data from. If it isn't in a manual (or in the manufacturer's online load data) then don't use the modified recipe. Use the recipe as listed there. Most reloading manuals have reduced loads data for approaching the 38 special levels. Again, find the load you want in a manual and use it exactly as shown. Arbitrarily lowering the load level from a manual below the starting load CAN be dangerous as too much air space in a cartridge can be as bad or worse than too much powder (detonation). Also the more air space in the cartridge the more varible the ignition can be dependent on how the powder lays in the cartridge in the gun when it is fired. Huge difference can occur in the pressures from the powder being all the way to the rear to all the way forward. The most repeatable loads often are the ones that are closer to filling the case, unless the powder has been designed to work equally well where ever it is inside the cartridge. Powders like W231 or Hodgdon HP38 or other fast powders that use small quantities are usually designed for small quantities of powder in the case whereas Unique and others MAY not be. So, follow the published recipes exactly as shown to stay safe. LDBennett

02-10-2009, 05:49 PM	#2
justdoit Member Join Date: Jan 2009 Location: GEORGIA Posts: 7	Re: Reloading for the .357 Magnum neilin, your load sounds ok but the magnum primers will up the pressure, you should use regular small primers with this load. as far as loading 357mag to 38spl specs, i don't think this would be good because there is about 2gr different in these loads, could cause a squib.