Interesting 357 magnum chrono results

[TargetTerror]

So I finally got around to chronographing my .357 mag and 38 special loads in my 6 inch 686 and 2 1/4 inch SP101. Here are the results. The chronograph was ~10 feet away from the muzzle. I was using WSPM for 357, WSP for 38. All cases were mixed headstamp, untrimmed, with a heavy crimp from a Lee FCD:

686
38 Special, 125gr Zero JSP, 5.1gr Unique - 890fps Avg velocity, 220 m/e

357 Magnum, 158gr Montana Gold CMJ, 12.5gr 2400 - 1076fps Avg velocity, 406 m/e

357 Magnum, 158gr Zero JSP, 15.1gr H110 - 1175fps Avg velocity, 484 m/e

357 Magnum, 158gr Zero JSP, 15.5gr H110 - 1168fps Avg velocity, 477 m/e


SP101
38 Special, 125gr Zero JSP, 5.1gr Unique - 764fps Avg velocity, 204 m/e

357 Magnum, 158gr Montana Gold CMJ, 12.5gr 2400 - 945fps Avg velocity, 312 m/e

357 Magnum, 158gr Zero JSP, 15.1gr H110 - 1070fps Avg velocity, 400 m/e

357 Magnum, 158gr Zero JSP, 15.5gr H110 - 1045fps Avg velocity, 380 m/e

357 Magnum, 158gr Magtech JSP loaded ammo - 1025fps Avg velocity, 367 m/e


I was surprised at the velocities for the 686. I would have thought them to be a bit higher. I was even more surprised at how little loss in velocity I get out of the SP101 - only ~100fps from almost a 4 inch shorter barrel! That is astounding. The Magtech's are also pretty astounding - they are just about a full-house 357 magnum load, and I will definitely continue to carry them.

I was also surprised at the performance of H110. Because velocity fell off in both guns as I jumped from 15.1 gr to 15.5 gr, 15.1gr seems to be right around max pressure. I'm not quite sure why velocity would actually decrease. I think my crimp was uniform, but admittedly one might have been more aggressive, I don't know.

Final note: try not to flinch when firing a snubbie with a full house load. The metal poles on the chronograph don't like getting hit