(https://i.postimg.cc/52qxgrJB/DSC02582-sized.jpg) (https://postimages.org/)
Cartridge is from Ammo Manufacture: Winchester .357 Mag PDX-1
Muzzle Velocity; Advertised: 1325 fps (No barrel length mentioned)
Actual Instrumental Velocity: 2½" barrel; 1162 fps.
4" barrel; 1222 fps. 39°F
Muzzle Energy; Advertised: 487 ft/lbs
(https://i.postimg.cc/GmQ4tt4n/DSC02595-2-sized.jpg) (https://postimages.org/)
(https://i.postimg.cc/250CRBV3/DSC02596-4-sized.jpg) (https://postimages.org/)
Brass Make/Headstamp: Winchester 357 MAG
Bullet Make/Weight/Contruction/Info: Winchester 125grs Bonded JHP; .3571" dia; .557" long.
Actual Weight: 124.3grs.
(https://i.postimg.cc/YjBHf6yD/DSC02589-sized.jpg) (https://postimages.org/)
(https://i.postimg.cc/m27zx8RD/DSC02593-sized.jpg) (https://postimg.cc/F7ss3bY5)
Crimp diameter:
C.O.A.L.: 1.571"
Primer: Winchester WSP
Case: Nickel
Powder Description/Positive ID/Type/Charge Weight: Medium Flake; 9.5grs.
(https://i.postimg.cc/FzLvLWGJ/DSC02588-sized.jpg) (https://postimages.org/)
(https://i.postimg.cc/7PGJ9qWS/DSC02584-sized.jpg) (https://postimages.org/)
(https://i.postimg.cc/3rs4bzsV/DSC02587-sized.jpg) (https://postimages.org/)
Wasn't expecting this flake powder to be in these rounds, but if these are mostly intended to be used in short barrel revolvers it makes sense. Better than trying to burn a whole bunch of ball powder in a few inches of barrel.
(https://i.postimg.cc/QtVhXxTm/DSC02591-sized.jpg) (https://postimages.org/)
(https://i.postimg.cc/RF89q51B/DSC02592-sized.jpg) (https://postimages.org/)
I don't have any data to support this, but it could be the new UNEQUAL powder from IMR. It is used in 38 S&W but no data shown for 357 Mag (yet)
I had 'heard' that IMR pulled Unequal off the market. Something about it caused some concern. I can't find any mention or listing of Unequal in IMR's online data site. I didn't check the shotshell data.. Might be a non-canister variant of some sort.