reloading .357 mag question

.357 mag · February 16, 2009, 09:20 PM

Hey,

I have been load ALL of my .357 loads with mag. primers. I have heard that mag. primers are not needed with lighter loads. Is this true? What is the pressure and fps differerance between standard and mag. primers? I'm loading .356 lead cast 158 grain swc with 5.6 grains of univeral. O, I'm just plinking and having fun. Nothing more.

thanks in advance,

.357 mag

joneb · February 16, 2009, 09:59 PM

I it depends on the powder and how cold the ammo is when you shoot it. For upper end loadings I use AA#9, and I have better accuracy with standard primers, but in cold temps. the mag. primer may be a better choice. Load data for H-110 and W-296 always lists Mag primers.

**Unclenick** · February 16, 2009, 11:04 PM

Basically any fine ball powder in the medium to slow burning rate range can derive some ignition consistency benefit from magnum primers. If you have access to a chronograph, you should work up your loads both with and without them and see which has the more consistent velocity in your gun? Cold weather, as mentioned, is another reason for them. You can also use the Winchester LP primer that is a dual purpose primer, covering both standard and magnum cartridge needs. I believe it accomplishes that by having standard primer brisance, but with a longer sustained flame. I've never heard any complaints about accuracy with it and know several bullseye shooters who use it happily.

.357 mag · February 17, 2009, 07:41 AM

thanks guys!

The_Vigilante · February 17, 2009, 07:44 PM

Aren't the large pistol primers too large for the .357?

warnerwh · February 18, 2009, 01:37 AM

The .357 takes small pistol primers.

afish4570 · February 19, 2009, 12:29 PM

Forget what brand they were but I had picked some up at the range several yrs. ago and threw them in my (junk drawer) I mean cartridge collection if you could call it that. Keep you eyes open when scrounging brass you never know what you might run into. Small Pistol Primers are the standard for 38/357.afish4570

AlaskaMike · February 19, 2009, 04:40 PM

Early .357 mag cases used large pistol primers.

February 16, 2009, 09:20 PM	#1
.357 mag Senior Member Join Date: September 22, 2008 Location: Central Illinois Posts: 193	reloading .357 mag question Hey, I have been load ALL of my .357 loads with mag. primers. I have heard that mag. primers are not needed with lighter loads. Is this true? What is the pressure and fps differerance between standard and mag. primers? I'm loading .356 lead cast 158 grain swc with 5.6 grains of univeral. O, I'm just plinking and having fun. Nothing more. thanks in advance, .357 mag

February 16, 2009, 11:04 PM	#3
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,080	Basically any fine ball powder in the medium to slow burning rate range can derive some ignition consistency benefit from magnum primers. If you have access to a chronograph, you should work up your loads both with and without them and see which has the more consistent velocity in your gun? Cold weather, as mentioned, is another reason for them. You can also use the Winchester LP primer that is a dual purpose primer, covering both standard and magnum cartridge needs. I believe it accomplishes that by having standard primer brisance, but with a longer sustained flame. I've never heard any complaints about accuracy with it and know several bullseye shooters who use it happily. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

February 17, 2009, 07:44 PM	#5
The_Vigilante Senior Member Join Date: May 17, 2008 Location: Far West Texas Posts: 200	reloading .357 mag question Aren't the large pistol primers too large for the .357? __________________ The_Vigilante Keeping the streets safe! A man can never own enough guns!

February 18, 2009, 01:37 AM	#6
warnerwh Senior Member Join Date: February 11, 2009 Posts: 329	The .357 takes small pistol primers. __________________ Portland, Or

February 19, 2009, 12:29 PM	#7
afish4570 Junior Member Join Date: February 10, 2009 Posts: 13	357 large primer cases......very unusual but a found a few too.... Forget what brand they were but I had picked some up at the range several yrs. ago and threw them in my (junk drawer) I mean cartridge collection if you could call it that. Keep you eyes open when scrounging brass you never know what you might run into. Small Pistol Primers are the standard for 38/357.afish4570

February 16, 2009, 09:59 PM	#2
joneb Senior Member Join Date: December 10, 2005 Location: Central , OR Posts: 1,888	I it depends on the powder and how cold the ammo is when you shoot it. For upper end loadings I use AA#9, and I have better accuracy with standard primers, but in cold temps. the mag. primer may be a better choice. Load data for H-110 and W-296 always lists Mag primers.

February 17, 2009, 07:41 AM	#4
.357 mag Senior Member Join Date: September 22, 2008 Location: Central Illinois Posts: 193	thanks guys!

February 19, 2009, 04:40 PM	#8
AlaskaMike Senior Member Join Date: September 26, 2005 Posts: 944	Early .357 mag cases used large pistol primers.