Underwood 357Sig 125gr Bonded FMJ pull-down

[The_Shadow]

Cartridge is from Ammo Manufacture: Underwood 125gr Bonded FMJ
Ballistics Information: 357 SIG
Muzzle Velocity: 1475 fps
Muzzle Energy: 603 ft. lbs
Brass Make/Headstamp: Star Line-Brass
Bullet Make/Weight/Construction/Info; Length 0.5400"/Dia. 0.3555":
125gr. JHP Actual weight 125.6 grains / 124.2 grains / 124.6 grains
C.O.A.L.: 1.1240" / 1.1235" / 1.1330"
Primer: Brass color
Case: Diameter 0.4220" all
Crimp Diameter 0.3785" / 0.3790" / 0.3790" crimp medium
Length 0.8600" / 0.8610" / 0.8600"
Powder Description/Positive ID/Type/ LongShot
Charge Weight:     9.8 grains / 10.0 grains / 10.0 grains













Hodgdon data shows 124gr Hdy XTP using 9.3 grains LongShot @ 1429 fps 37,900 psi (inside MAP)
Max average pressure for the 357Sig is 40,000psi

[Intercooler]

LongShot goes a long ways 

[The_Shadow]

In the last picture one cartridge was damaged by something putting a dent into the casing...even though Underwood's ammo is over the book listed data of Hodgdon, I don't think that alone was the cause for the KA-Boom.
I still think the incident was related to bullet set back, which in turn caused a sever pressure spike, that resulted in the catastrophic failure of the gun!

[Intercooler]

This is the ammo from the blown up Glock? The one pictured looks like it has been chambered or something in a bad way. Mark on the front, dent in the middle and marks on the headstamp.

[The_Shadow]

BTW- a review of my notes shows that Double Tap was using 10.0 grains of LongShot under the 125 Speer Gold Dots Loaded in the 9x25Dillon, these ran 1525-1475 fps from my S&W1006 5" conversion

[REDLINE]

Interesting.

[The_Shadow]

BTW the SwampFox 40S&W Ammo 165gr GDHP loading that blew-up another Glock 29 with a 40S&W conversion barrel, was also loaded with 10.0 grains LongShot powder, this being a sever case blowout.

[REDLINE]

Wow.  Wish we knew what pressure those were loaded to.

[Pctechdude]

Oddly enough, I've loaded plenty of 357 Sig. I've always used AA#9 and 800-x. With a Speer gold dot 125gr bullet, and 10gr 800-x it's compressed. Virtually eliminates set back and achieves 1450fps from a 4" barrel without going over on pressure.