357 Mag Loads; 140-gr. Hornady FTX & Longshot Powder

[Bart B.]

Hodgdon's on line reloading data site for the subject load starts at 5.5 gr. (1091 fps, 22,000 psi) and max's out at 7 gr. (1358 fps, 33,800 psi). Why no data for pressure up to the low 40,000 psi levels as other bullet weights with Longshot list? Is there an excessive pressure rise/level with heavier charges for that FTX bullet and not the 140-gr. XTP ones?

 

[buck460XVR]

They show the same scenarios for the FTX regardless of powder, not just with Longshot. This includes H110/W296 and IMR4227. Shoot Hodgdon an e-mail...they generally reply quickly.

 

[Sevens]

Are you sure you are reading those tables correctly?

Hodgdon isn't likely to ever list .357 Magnum loads with any bullet or any powder to the low 40,000 psi levels as that is beyond SAAMI max.

What I see on there are CUP loads listed, with the only PSI load listed being the 140 grain FTX. CUP and PSI are not the same and there's no "formula" for a direct conversion from one to the other. They are test results from two different methods.

It's been my experience that while Longshot is one of the best powder in some places (10mm!), and it works well in .357 Magnum, it's never going to give you the most bang for the buck in .357 Magnum. You'll need a better powder to do that.

If you want the absolute maximum speed on the 140gr FTX in .357 Magnum while staying within SAAMI max, you'll be using some powder other than Longshot.

Alliant Power Pro 300-MP may be that powder, but load data is extremely scarce.

 

[Bart B.]

Sevens asks if I'm reading those tables correctly.

No, I am certainly not for that bullet. Thanks for pointing that out. Hodgdon didn't stick that PSI number in the middle of all the other CUP ones just to mess me up. First time in several years I misread listed pressure types.

I'd made some tables showing the approximate change in velocity and pressure for 1/10th grain charge increments from start to max for all of Hornady's 140-gr. XTP and FTX bullets and completely missed that FTX bullet's use of the other pressure measuring system.

I've been using W296 in my S&W Mod. 19 .357 for max loads but wanted to try Longshot to see how it performed with "-P" reduced loads; peak pressures in the 32,000 CUP range. Especially to see what the muzzle flash difference is. W296 max loads light up the night with a pretty bright flash.