I got one I use it is a 158 grain jacketed hollow point I use Noslers, but any will do. 14.7 grains of 2400 in a Federal case. Start with standard Winchester primers. I have another I will need to look it up to make sure, but it is a red dot load that is mild.
I don't have an SP but I've been loading for .357 for a long time. My favorite is a 125 gn hollow point with a whole bunch of H110 in a Winchester case with a Federal or Winchester primer. In a short barrel like the SP, the flash will probably light up a city block. Even if ya don't hit him, he'll be so sunburned, he won't be much interested in a fight.
Well Pete I don't have an SP101 but I saw that you are using a 158gr SWC. So I'll chime in. I have recently been testing some Oregon Trail 158gr SWC in my 50th Ann. .357 Blackhawk. The results I am getting are typical of some bullets. My lighter loads in .38 brass and .357 brass are not great, 3" groups at 25 yards. As I increase the charge using 2400 and IMR4227 (in the .357) the groups are starting to go down close to 2". I am using 13.0 grains of 2400 and 14.0 grains of 4227. But I have room to increase either powder up another couple of grains. DISCLAIMER: I am not at home to check my log book so don't use these charges unless verified in a manual.
It seems this bullet needs a good kick in the pants to obturate and fill the grooves. IMR4227 and 2400 are two of my most used powders in my .41mag BH. In the .357 I am still going to try Bluedot and H110.
When I have settled on loads for this gun then I will try the same loads in my 4" GP100 and see how they do there. If I get around to taking pictures of the targets I'll post them so you can see the progression of the load on paper.
These are the targets I mentioned above. The bullseyes are 3" shot at a paced 23 yards. The two on the left are with 2400, top is 12.0gr and the bottom is 13.0gr. The two on the right are with 13.0gr of IMR4227 on the top and 14.0gr on the bottom. I will continue to increase the charge of each powder to see if the groups keep getting smaller.
The grips on the pistol are Eagle's Ultra Ivory and I was quite pleased with the fit and off white appearance as well as the fact that they don't look and feel like plastic. They do look better in person (is that grammatically correct?).
I was also interested in loads for the 158gr SWC. Looks like some of these velocities are a little brisk for 10-12 bullet hardness. Are these warm SWC loads leading your Rugers?
I have an SP101 and GP100 in 357 and have some Speer and Hornady .358 SWC on order and are looking for top accuracy at 25yds for these. (with least amount of fouling of course)
I have a load of 7 gr. of Unique with a 158 gr. LSWC from Missouri Bulltes with a BHN of 16. I am casting my own now and use 6.2 gr. of Unique with Wheel weight alloy plus 2% Tin using a custom mold. I recommend starting with a published load and then working up from there and see what YOUR gun tells you. (and what your hand tells you)
One of my manuals has 5.5 to 6.0 of Unique in a 357 case for my Speer LSWC 158gr. It notes that this load is not maximum pressure. I take that to mean the load is not max pressure for the cartidge but it is max pressure for the bullet hardness of that LSWC (Speer 4624)
I am going to try some 38 special and 357 magnum rounds with my new LSWCs. I also picked up a few factory 38special LSWC 158gr (shown below) for benchmark/baseline evaluation purposes: