357 mag load

Poconolg · March 9, 2022, 07:05 AM

Looking to find a load for 357 mag using Herco and 125gr bullets. Thanks for thee help.

AVirginian · March 9, 2022, 09:19 AM

According to a very old site

Herco From 9.6 grains to 11.5 grains
CCI-550 Primer

Of course start low and work up and chrono everything.

Use at your own risk.

Shadow9mm · March 9, 2022, 10:26 AM

2008 lee, with a 125g jacketed bullet
herco
start 9.0 at 1473fps
max 9.8 at 1590fps and 33600psi

my 2021 lee manual no longer lists that load
my lyman manual has no data for that bullet and powder
my speer manuals has no data for the bullet and powder
alliant lists no 357 mag data with that powder.

based on the burn rates should be ok in 357

you didnt mention plated or lead. lead does not like to be pushed over 1100-1200fps without gas checks.

rclark · March 9, 2022, 11:29 AM

Reference your manuals .... Look under .38 Special... You might find more data there. No reason to load so 'hot'. I tested 5.0g (890fps) to 7.5g (1140fps) of Herco under a 158g SWC in .357. Herco doesn't need a magnum primer. I don't use/load the ultra light 125g bullets. You didn't say if the 125s were lead, plated, coated, or jacketed or style.

Poconolg · March 9, 2022, 12:50 PM

I am using X-treme 125gr bullets. Have been using them for years with various powder and get good accuracy. Tried 9.1 gr Herco and got flattened primers. Would like to know how low I can safely go? Cannot find any info for 125gr bullets with Herco.

Shadow9mm · March 9, 2022, 01:20 PM

sticky extraction? flattened or flowed primers? most of my primers flatten a bit, usually a sign of a good max load for me. however if its flowed, like filling up the entire primer pocket its time to back off. thats how I do it anyway.

If you not comfortable with the load, what I would do in this circumstance, is back off 0.5g and test again, say 8.6g and see how things act.

cdoc42 · March 9, 2022, 01:42 PM

Poconolg, I checked my "library" of manuals for .357 loads

Hornady Vol II 1973 does not list Herco with 125gr, but does list it for 158gr (start 6.5gr -800 fps; Max 9.5gr - 1100 fps)

Hodgdon 25th Ed 1989 - NO Herco for 125gr or any bullet weight listed

Hodgdon 26th Ed 1994 - Same as 25th Ed

Lyman 43rd Ed 1964 -No Herco listed for any bullets

Lyman "Ideal" handbook #38 1951 - only bullet listed is 156gr Lead and no Herco listed.

What is your reason for using Herco if you've been getting good accuracy with other powders for years?

Hammerhead · March 9, 2022, 02:38 PM

Older Alliant data lists 9.8 Herco max with a 125 jsp, less 10% for starting would be 8.8 grains.
The only other data I have is Sierra, 9.6 start, max 11.5 with a 125 jsp.
I would be comfortable working down from 9.1 in .2 increments until you find a load you like.

Poconolg · March 9, 2022, 02:56 PM

I was given 2lbs of Herco . That is why I am looking for loads.

rclark · March 9, 2022, 03:36 PM

Looking at .38 Special, the loads I found was Herco 5.6gr to 5.8gr under Jacketed 125g Bullet. So you can go at least that low. I'd start at 6.0gr and work up. Looks like your range is from 5.8 to 9.8 (from above data) . Plenty of room to play as Herco is not pressure sensitive. As I said above you don't have to load 'hot'. Enjoy.

**44 AMP** · March 10, 2022, 07:33 PM

FWIW

Speer #8 (1970)
.357 Mag
speer cases
CCI 550 primer
Speer 125gr Soft point

Herco
10.0gr 1245fps
11.0gr 1305fps

test gun S&W Model 27 6" twist 1-18 3/4

Colorado Redneck · March 11, 2022, 03:05 PM

Are the Extreme Bullets copper plated or metal jacket?
Copper plated are different in the friction department, so consider that.

38 Special...125 gr. Nosler JHP....4.9--5.9 grains

357 Magnum
125 gr. Sierra JSP.....9.6--11.4 grains

There was data for Lyman cast bullets using Linotype 150 gr starting at 6.2 and max of 7.8.

Poconolg · March 12, 2022, 05:52 AM

Bullets from Xtreme are copper plated

Carriertxv · March 12, 2022, 10:39 AM

Look at Unique data and go about 0.5 to 1.0 grains more for Herco. This has worked well for me with my guns and components.

March 9, 2022, 07:05 AM	#1
Poconolg Senior Member Join Date: April 5, 2015 Posts: 171	357 mag load Looking to find a load for 357 mag using Herco and 125gr bullets. Thanks for thee help.

March 9, 2022, 11:29 AM	#4
rclark Senior Member Join Date: February 12, 2009 Location: Butte, MT Posts: 2,650	Reference your manuals .... Look under .38 Special... You might find more data there. No reason to load so 'hot'. I tested 5.0g (890fps) to 7.5g (1140fps) of Herco under a 158g SWC in .357. Herco doesn't need a magnum primer. I don't use/load the ultra light 125g bullets. You didn't say if the 125s were lead, plated, coated, or jacketed or style. __________________ A clinger and deplorable, MAGA, and life NRA member. When guns are outlawed, only outlaws will have guns. Single Action .45 Colt (Sometimes colloquially referred to by its alias as the .45 'Long' Colt or .45LC). Don't leave home without it. That said, the .44Spec is right up their too... but the .45 Colt is still the king.

March 9, 2022, 01:20 PM	#6
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 4,601	sticky extraction? flattened or flowed primers? most of my primers flatten a bit, usually a sign of a good max load for me. however if its flowed, like filling up the entire primer pocket its time to back off. thats how I do it anyway. If you not comfortable with the load, what I would do in this circumstance, is back off 0.5g and test again, say 8.6g and see how things act. __________________ I don't believe in "range fodder" that is why I reload.

March 9, 2022, 03:36 PM	#10
rclark Senior Member Join Date: February 12, 2009 Location: Butte, MT Posts: 2,650	Looking at .38 Special, the loads I found was Herco 5.6gr to 5.8gr under Jacketed 125g Bullet. So you can go at least that low. I'd start at 6.0gr and work up. Looks like your range is from 5.8 to 9.8 (from above data) . Plenty of room to play as Herco is not pressure sensitive. As I said above you don't have to load 'hot'. Enjoy. __________________ A clinger and deplorable, MAGA, and life NRA member. When guns are outlawed, only outlaws will have guns. Single Action .45 Colt (Sometimes colloquially referred to by its alias as the .45 'Long' Colt or .45LC). Don't leave home without it. That said, the .44Spec is right up their too... but the .45 Colt is still the king.

March 10, 2022, 07:33 PM	#11
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 30,466	Herco load FWIW Speer #8 (1970) .357 Mag speer cases CCI 550 primer Speer 125gr Soft point Herco 10.0gr 1245fps 11.0gr 1305fps test gun S&W Model 27 6" twist 1-18 3/4 __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

March 9, 2022, 09:19 AM	#2
AVirginian Senior Member Join Date: February 6, 2014 Posts: 128	According to a very old site Herco From 9.6 grains to 11.5 grains CCI-550 Primer Of course start low and work up and chrono everything. Use at your own risk.

March 9, 2022, 10:26 AM	#3
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 4,601	2008 lee, with a 125g jacketed bullet herco start 9.0 at 1473fps max 9.8 at 1590fps and 33600psi my 2021 lee manual no longer lists that load my lyman manual has no data for that bullet and powder my speer manuals has no data for the bullet and powder alliant lists no 357 mag data with that powder. based on the burn rates should be ok in 357 you didnt mention plated or lead. lead does not like to be pushed over 1100-1200fps without gas checks. __________________ I don't believe in "range fodder" that is why I reload. Last edited by Shadow9mm; March 9, 2022 at 11:40 AM.

March 9, 2022, 12:50 PM	#5
Poconolg Senior Member Join Date: April 5, 2015 Posts: 171	I am using X-treme 125gr bullets. Have been using them for years with various powder and get good accuracy. Tried 9.1 gr Herco and got flattened primers. Would like to know how low I can safely go? Cannot find any info for 125gr bullets with Herco.

March 9, 2022, 01:42 PM	#7
cdoc42 Senior Member Join Date: March 13, 2005 Location: Pennsylvania Posts: 1,772	Poconolg, I checked my "library" of manuals for .357 loads Hornady Vol II 1973 does not list Herco with 125gr, but does list it for 158gr (start 6.5gr -800 fps; Max 9.5gr - 1100 fps) Hodgdon 25th Ed 1989 - NO Herco for 125gr or any bullet weight listed Hodgdon 26th Ed 1994 - Same as 25th Ed Lyman 43rd Ed 1964 -No Herco listed for any bullets Lyman "Ideal" handbook #38 1951 - only bullet listed is 156gr Lead and no Herco listed. What is your reason for using Herco if you've been getting good accuracy with other powders for years?

March 9, 2022, 02:38 PM	#8
Hammerhead Senior Member Join Date: June 1, 2004 Location: Minnesota Posts: 2,432	Older Alliant data lists 9.8 Herco max with a 125 jsp, less 10% for starting would be 8.8 grains. The only other data I have is Sierra, 9.6 start, max 11.5 with a 125 jsp. I would be comfortable working down from 9.1 in .2 increments until you find a load you like. Last edited by Hammerhead; March 9, 2022 at 02:44 PM.

March 9, 2022, 02:56 PM	#9
Poconolg Senior Member Join Date: April 5, 2015 Posts: 171	I was given 2lbs of Herco . That is why I am looking for loads.

March 11, 2022, 03:05 PM	#12
Colorado Redneck Senior Member Join Date: January 7, 2008 Location: Northeast Colorado Posts: 2,006	One Book/One Caliber copyright 2000 Are the Extreme Bullets copper plated or metal jacket? Copper plated are different in the friction department, so consider that. 38 Special...125 gr. Nosler JHP....4.9--5.9 grains 357 Magnum 125 gr. Sierra JSP.....9.6--11.4 grains There was data for Lyman cast bullets using Linotype 150 gr starting at 6.2 and max of 7.8.

March 12, 2022, 05:52 AM	#13
Poconolg Senior Member Join Date: April 5, 2015 Posts: 171	Bullets from Xtreme are copper plated

March 12, 2022, 10:39 AM	#14
Carriertxv Senior Member Join Date: January 19, 2013 Posts: 268	Look at Unique data and go about 0.5 to 1.0 grains more for Herco. This has worked well for me with my guns and components.