Goal: Develop a 357 Magnum load that is medium power (low recoil), low blast and flash, with a bullet that will expand quickly and reliably.
Testing components:
• Case – mixed, mostly Starline, Winchester, PMC, with a smattering of R-P
• Primer – CCI Small Pistol Magnum
• Powder – IMR SR4756
• Bullets – 158 grain SWC and SWCHP-GC
• Measured Powder (beginning load with Lee Dipper, Pacific PM for latter loads)
• Medium-Heavy Crimp in crimping groove
Notes: Used Ruger NMBH 4.62" barrel. SWC is bevel based bulk hard-cast, HP is gas checked soft-cast, and both bullets are available commercial bullets. Pro Chrono was used and most testing took place in 100+ degree temperatures. Five shots per average with HP, and 6 shots with SWC used as calibration.
Results (rounded to the nearest 10 and with HP shown) – Average Velocity:
6.4 grains = 880 fps - light recoil with no signs of high pressure – spent cases dropped out.
7.0 grains = 1020 fps – light recoil with no signs of high pressure – spent cases dropped out.
7.5 grains = 1080 fps = light (but snappy) with no signs of high pressure – 5 spent cases did not drop out, but extracted normally – 1 case (in parrot chamber) required a slightly heavier than normal nudge to get it moving but broke loose with little movement.
8.0 grains = 1160 fps = recoil was snappy with a couple signs of lower end high pressures – 5 spent cases did not drop out and all required a nudge to get them moving (similar to typical full power load extraction) – 1 case (in parrot chamber?) required slightly heavy pressure (not needing a tap to move) to move case and moderate pressure to fully extract the case – all primers were flattened and not completely round, but no primer craters. It should also be noted that one shot (only one) exceeded 1200 fps and it might have been the one giving sticky extraction – and may not have been in the parrot chamber.
I hope this information will be of some interest and help to someone. I sure would have liked to have found it when I began working on this load. Thanks.
Testing components:
• Case – mixed, mostly Starline, Winchester, PMC, with a smattering of R-P
• Primer – CCI Small Pistol Magnum
• Powder – IMR SR4756
• Bullets – 158 grain SWC and SWCHP-GC
• Measured Powder (beginning load with Lee Dipper, Pacific PM for latter loads)
• Medium-Heavy Crimp in crimping groove
Notes: Used Ruger NMBH 4.62" barrel. SWC is bevel based bulk hard-cast, HP is gas checked soft-cast, and both bullets are available commercial bullets. Pro Chrono was used and most testing took place in 100+ degree temperatures. Five shots per average with HP, and 6 shots with SWC used as calibration.
Results (rounded to the nearest 10 and with HP shown) – Average Velocity:
6.4 grains = 880 fps - light recoil with no signs of high pressure – spent cases dropped out.
7.0 grains = 1020 fps – light recoil with no signs of high pressure – spent cases dropped out.
7.5 grains = 1080 fps = light (but snappy) with no signs of high pressure – 5 spent cases did not drop out, but extracted normally – 1 case (in parrot chamber) required a slightly heavier than normal nudge to get it moving but broke loose with little movement.
8.0 grains = 1160 fps = recoil was snappy with a couple signs of lower end high pressures – 5 spent cases did not drop out and all required a nudge to get them moving (similar to typical full power load extraction) – 1 case (in parrot chamber?) required slightly heavy pressure (not needing a tap to move) to move case and moderate pressure to fully extract the case – all primers were flattened and not completely round, but no primer craters. It should also be noted that one shot (only one) exceeded 1200 fps and it might have been the one giving sticky extraction – and may not have been in the parrot chamber.
I hope this information will be of some interest and help to someone. I sure would have liked to have found it when I began working on this load. Thanks.
) Your load with 4756 @ 8.0gr/158SWC was also in my log & marked as "accurate". I got to wondering about what pressure it was & checked Hodgdon's online site. It lists a 158gr LSWC starting at 5.0gr.@ 13.8K psi & max at 6.5gr.@ 27.6K psi. I know you said you were looking for a medium power load, but I wonder what pressure 8.0grs is given Hodgdon's data & a SAAMI 35K psi max.? (I hate to wonder what Speer's #8 double-digit loads were! 
)
