I've been using 158gn Laser Cast over 13 gn of 2400, WSPM, 357 Win brass, at 1193fps, (5 shot average w/ crono) with a PF of 190, thru a ported 627-PC, for plates...
I would like to back down to 1000-1100fps. Does Alliants 2400 have the latitude to reduce the charge for a 160-170 PF...
Was thinking to start at 12gn, and work my way down...

Yes, 2400 can be safely downloaded but you will get more unburnt powder the lower the pressures get. It will become quite dirty with lower pressures. (not unlike many powders at lower pressures) If the loads become unacceptable you can go to a faster powder like Power Pistol, Longshot, HS-6, Universal, Unique and other powders in that burn rate range. My favorite middle to middle hot .357 Magnum powder is HS-6 especially with lead bullets.

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SWCA #3437

Really? Who'd a thunk it!

I'll get everyone to try HS-6 at least once before I'm done!

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Freedom is never free!!
SWCA #3437

Good morning
Try Unique.. yea it is as old as smokeless powder gets but still is what it´s name implies UNIQUE.
5- 5.5 grains should do what you are looking for.

There are other powders out there that would be much better suited to reduced loads. If all you are looking for is 1100fps then let me suggest another powder,SR4756. You will not be able to use current data for it though, as it is so anemic. A load between current maximum and older data minimum would be just fine for what you want.

There will be no unburnt powder or nasty residue such as you will encounter by downloading 2400. W231/HP-38, AA#5, Unique and other powders in that same burn rate will be much better suited to what you are trying to accomplish.

The "dirt" left behind is not the main problem with downloading powders. It is a factor but not the "main" one that I see. I am a numbers guy. Sometimes they correlate to accuracy, sometimes they don't. Being a stickler for the numbers, I hate to see erratic numbers pop up on my chronograph. When a powder is loaded light for it's burn rate, almost without fail, the numbers go to pot fast. To me that means that I am not putting it in a place where it can "win". I use a different powder at that point.


Case in point: I had 8lb of a MILSURP powder that loaded like AA#9 to H110. I wanted to find some loads that I could use in every caliber I loaded to take advantage of the $8lb powder. Well, what I got was huge ES and SD numbers. I quit and went back to the powders suggested for the loads.

FWIW

I don't have a lot of experience with 2400 yet, so bear with me.

I ran the numbers on a reduced load calculator and came up with 10.4 grs. for 1000 fps. and 11.7 grs. for 1100 fps. I had noticed some charges in loading manuals about the same for 158 gr. lead bullets for starting loads so you should be alright to try them to see how they work.

My actual experience with mid-range 158gr lead loads in .357:
HP38/231 ends all the guessing and conjecture in the 1000 to 1100 fps range. Just use the Hodgdon tables and your chrono to adjust to the exact power factor required. Consistent and reliable, have used it for decades.

I have helped several beginning competitive shooters solve their problems of using too-slow powders in mid-range loads by getting them to use HP38/Win 231 or Titegroup. In spite of all the guessing and theory, actual experience shows when the pressure drops too low, the loads become erratic and sooty.

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I agree, when you use a slow powder at too low a pressure the ammo becomes very erratic. A faster powder will work better. That's why I suggested HS-6 above but W231 will also work. I use a lot of both those powders.

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Freedom is never free!!
SWCA #3437

I have had excellent results with Universal - 1125 f/s.

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US Army '72-'95