I was asked to post a report after I posted in another post on this little project. I finally was able to come to a 90% to 95% end to the project tonight.
I bought a 357 SIG conversion barrel due to a curiosity about this cartridge that I couldn't get rid of. After receiving the barrel, I went to the gun range and found that with the standard 15# recoil spring, the empty casings were being thrown a minimum of 15 to 20 feet and beyond. That had to change and I bought a tuners spring kit from Wolff to help keep the empty casings with in the 6 to 8 foot distance. I put in a 22# recoil spring and shot 10 rounds of Winchester White Box as a test and the 22# spring was OK.
Reloading the 357 SIG was a challenge, but thanks to posts here and another site I was able to come up with a process to follow.
After trying to put together some dummy rounds to check to see if they would feed, I came to the conclusion that "standard" 9 mm projectiles will not necessarily work in the 357 SIG round. The 357 SIG needs a projectile with a long straight side and a short fat Ogive on the projectile. The RMR MPR comes to mind as well as their "Match Winner". I was able to feed these two projectiles 5 times into the chamber without any significant setback. Others like the Speer 124 grain GDHP projectiles would set back after the first feed. Speer makes a 125 grain GDHP specifically for the 357 SIG, and now I know why.
I loaded up 20 Speer 125 grain TMJ projectiles and headed to the range with 10 Win WB 125 grain factory loads. I also shot 10 rounds of Browning 180 grain factory ammo. I've still have a lot of work to do with adjusting to the 357 SIG, but in time I think I can shoot this very well.
And BTW, it does have more recoil than 40 S&W, but manageable.



And just for fun, some 124 grain GDHP through the P-10S using Sport Pistol
