.357 Magnum Loads Under Performing

[Arrowshot]

Having some issues getting higher FPS’s out of my .357 Colt Lawman MK III pistol loads. Here are the loading specs and range results. After a bit of research decided to drop the Titegroup powder loads (burns too fast) and switched strictly to Longshot. Loaddata.com shows Longshot loads of 8.7 (1,230) - 10.0 (1,368) but I have somewhat hesitated to go higher than 9.0 based on the Hodgden data. Even my load of 8.7 of Longshot did not come close to what Hodgden (1,529) or Loaddata.com (1,230) indicated it should be. So, based on the results below will loads of Longshot (9.1-10.0) be exceeding safe ranges? Suggestions are welcome!

.357 Magnum

• Sierra 125 grain Jacketed Hollow Points
• Starline brass
• Trim length – 1.280
• Recommended COAL – 1.580 (COAL is 1.580)
• Titegroup – 6.8 (1,456) to 7.5 (1,586) This is from Loaddata.com for 125 gr Hornady XTP.
• Longshot – 7.2 (1,332) to 8.5 (1,502) This is from the Hodgden reloading site for 125 gr Hornady XTP.

2022-12-02 range results using small pistol primers

• 7.0 grains Titegroup: 1128, 1106, 1112, 1055, 1097, 1030, OK grouping but speeds are not as fast as load data indicates they should be. (Titegroup – 6.8 (1461) to 7.5 (1586))
• 7.3 grains Titegroup: 1158, 1124, 1104, 1101, 1099, 1102

2022-12-26 range results using small pistol primers

• 7.8 grains of Longshot - 900, 1009, 991, 964, 1011
• 8.2 grains of Longshot - 771, 815, 995, 866, 865, 877 (Makes no sense based on group above but no good explanation unless I screwed up and went with 7.2 instead of 8.2)
• 8.8 grains of Longshot powder - 922, 1039, 1098, 1025, 1032, 1032

2023-01-04 using small rifle primers

• 7.8 grains of Longshot - 897, 909, 938, 831, 811, 919
• 8.2 grains of Longshot - 889, 880, 916, 648?, 969, 1011
• 8.5 grains of Longshot - 1001, 969, 985, 1010, 906, 968

2023-01-16 using magnum small pistol primers

• 8.6 grains of Longshot - 992, 1025, 1025, 904, 1000, 1019
• 8.8 grains of Longshot - 1000, 1057, 935, 970, 972, 1026
• 9.0 grains of Longshot - 904, 1111, 1070, 1098, 1043, 992

 

[Coyotefurharvester]

Have you confirmed your charge weights, or using some type of powder dispenser?

 

[C_Ackley]

My first inclination is to question barrel length, which plays a significant role. Look at what they used to get their data.

 

[sneakboxer]

Hodgdon is using a 10in barrel that might not even be vented. It might be pretty tough hitting those speeds with a shorter barrel and a cylinder gap. For me I would not venture much over max printed loads with a nice Colt like you have.

 

[357Mag]

Having some issues getting higher FPS’s out of my .357 Colt Lawman MK III pistol loads. Here are the loading specs and range results. After a bit of research decided to drop the Titegroup powder loads (burns too fast) and switched strictly to Longshot. Loaddata.com shows Longshot loads of 8.7 (1,230) - 10.0 (1,368) but I have somewhat hesitated to go higher than 9.0 based on the Hodgden data. Even my load of 8.7 of Longshot did not come close to what Hodgden (1,529) or Loaddata.com (1,230) indicated it should be. So, based on the results below will loads of Longshot (9.1-10.0) be exceeding safe ranges? Suggestions are welcome!

.357 Magnum

• Sierra 125 grain Jacketed Hollow Points
• Starline brass
• Trim length – 1.280
• Recommended COAL – 1.580 (COAL is 1.580)
• Titegroup – 6.8 (1,456) to 7.5 (1,586) This is from Loaddata.com for 125 gr Hornady XTP.
• Longshot – 7.2 (1,332) to 8.5 (1,502) This is from the Hodgden reloading site for 125 gr Hornady XTP.

2022-12-02 range results using small pistol primers

• 7.0 grains Titegroup: 1128, 1106, 1112, 1055, 1097, 1030, OK grouping but speeds are not as fast as load data indicates they should be. (Titegroup – 6.8 (1461) to 7.5 (1586))
• 7.3 grains Titegroup: 1158, 1124, 1104, 1101, 1099, 1102

2022-12-26 range results using small pistol primers

• 7.8 grains of Longshot - 900, 1009, 991, 964, 1011
• 8.2 grains of Longshot - 771, 815, 995, 866, 865, 877 (Makes no sense based on group above but no good explanation unless I screwed up and went with 7.2 instead of 8.2)
• 8.8 grains of Longshot powder - 922, 1039, 1098, 1025, 1032, 1032

2023-01-04 using small rifle primers

• 7.8 grains of Longshot - 897, 909, 938, 831, 811, 919
• 8.2 grains of Longshot - 889, 880, 916, 648?, 969, 1011
• 8.5 grains of Longshot - 1001, 969, 985, 1010, 906, 968

2023-01-16 using magnum small pistol primers

• 8.6 grains of Longshot - 992, 1025, 1025, 904, 1000, 1019
• 8.8 grains of Longshot - 1000, 1057, 935, 970, 972, 1026
• 9.0 grains of Longshot - 904, 1111, 1070, 1098, 1043, 992

Arrows hot -

Howdy !

I DK why exactly you are shooting Longshot and Tight group loads ? Only powders you have, or can easily get ?

RX -
14.5gr WW296 ( H110 same stuff ) and SP Magnum primer, under a Lyman SWC of 158-172gr ( doesn't have to be gas checked ). Jacketed 158s work ok, too !
Bona fide' magnum load.

.357Mag and WW296 man.... that's like cornflakes and milk !

Just sayin' .


With regards,
357Mag

 

[Fuj]

Barrel Length ?? Next question would be what velocities do
you expect ?? Those powders your using would be good for
target loads, but It's a .357. I get 1300 fps easily with Unique
and the 125 in a 6" Smith mod-66. 150's and up it's 2400 powder.
296 is another great powder but it needs to be loaded hot. Do not
load light with 296.

 

[Lone Hunter]

Look at 2400 and WW296/H110….Look at Lyman Reloading Reloading Manual , has a lot of good data.

 

[K22]

For full power loads in the 357, I've always used 2400 with excellent results for hunting. The 140 JHP is an excellent choice with this powder and provides a good balance of velocity and energy for hunting purposes.

Fast burning powders are not a good choice in this cartridge for full power loads. They reach peak pressure to fast. They are much better suited for milder loads, especially with lighter bullets like the 110 or 125's. Slower burning powders like 2400, 296 and H110 are better choices for heavy loads in the 357 especially with 140 and 158 grain bullets.

Don't expect to get the same velocity published in reloading manuals since in some cases, they are using pressure barrel without a cylinder gap and / or longer barrels which are less common in factory revolvers.

 

[mac86951]

Question, have you removed the cylinder and inspected the forcing cone? Chance it's cracked? Likewise, what's your pistol's gap between cone and cylinder?

 

[JSH]

As mentioned I would not crowd full tilt loads in a Colt or a SW for that matter. A steady diet will make them rattle as well.
Full tilt and then some, get a GP100 and don’t look back. My GP thrives on 170-180’s and lil gun. I have seen zero issues with the lil gun, it I will admit to using it now for hunting loads only.

 

[ebb]

8.2 on 12 26 where you have one in the group going 771 and another going 995 that and all the low numbers makes me think you need a new chronograph.

 

[mongo chicago]

Old Blue Dot gave me the best velocities in both 44 magnum and 357 magnum, and with listed lower pressures than other powders. I don't remember the exact loading for the 357 but it was somewhere in the 15 grain range. The 44 loading was 18.5 grs. behind a 240 gr bullet. Got the loading from Gun Digest DECADES ago. I think it was the edition with a Ruger Super Blackhawk on the cover. I wouldn't use those loads in anything but a Ruger, but some more recent reloading manuals have Blue dot loads though they are loaded down from what I used.

 

[Chappy]

As mentioned I would not crowd full tilt loads in a Colt or a SW for that matter. A steady diet will make them rattle as well.
Full tilt and then some, get a GP100 and don’t look back. My GP thrives on 170-180’s and lil gun. I have seen zero issues with the lil gun, it I will admit to using it now for hunting loads only.

You aren't lying about the GP-100 with 180s. Especially shooting Alliant 300-MP, you'll get some really impressive numbers on the chronograph!

 

[Andy Work]

I always had good luck with WW296 and 140 JHPs. Are you getting a good uniform crimp on your loads?