I want to work up some low power .357 SIG loads for "plinking" and to start new shooters with.
My current .357 SIG load is 8.4 gr. of Longshot behind a 125 gr. Montana Gold bullet. This gives me about 1,350 fps.
I'm looking for something in the neighborhood of 1,100-1,200 fps.
The Hodgdon Reloading Data Center lists the following starting loads for .357 SIG with 124 gr. bullets.

Powder Grains Velocity Pressure
Longshot 8.3 1,344 fps 33,500 PSI
CFE Pistol 6.6 1,181 fps 27,400 PSI

I started with 7.0 gr. of CFE Pistol, and I notice there is much more empty space in the case than with 8.3 gr. of Longshot. Is there any reason it wouldn't be safe to go lower than the published starting load with Longshot? I can't think of any, but I've never deviated from published ranges before, other than using the 124 gr. data for the 125 gr. bullets, but staying away from maximum loads.

I'm sure I can get where I want to go with CFE Pistol, but it would be nice to not have to stock two powders.

CFE Pistol is a faster burning powder, hence the need for a lower starting load. I would not reduce the beginning Longshot load. Your slide may not cycle and worse you could end up with a squib.

I recently went down this low-power road. Here is my experiance:

5.7g of Tite Group behind a 125g MG is my standard target load. I clocked this load at around 1100+, IIRC. Recently, I had the desire to buy a 9mm barrel for my P226 SSE. Wanted to shoot faster with much less recoil. I couldn't justify a $250+ purchase, so I tried another path: I replaced the 20# recoil spring with a 14# and reduced the charge in steps. 3.8g of TG was the bottom limit to cycle the slide. This made a soft-shooting pistol! I wouldn't be too concerned with a charge not filling the case.

edit: wrong starting load: 5.7, not 4.7

This message has been edited. Last edited by: cne32507,

I think I'll start working it down a couple of tenths at a time. I can't imagine I wouldn't see accuracy or slide function issues long before there would be a risk of a squib.

I loaded 5 rounds each of 4.2, 4.0, 3.8, 3.6 (weighing each charge) changed the recoil spring and headed for a nearby indoor range. Like I posted, the 3.8 cycled but the 3.6 did not. My Lee is not dead balls accurate so I plan to use a 4.0 setting to make sure no charges fall below 3.8.

The issue I see in using fast powder (as I do) is that a couple of 1/10's can really make a difference in velocity, which affects accuracy and, in marginal loads, could affect the safe action of the pistol. A slower powder wouldn't be as picky. Others with more experience should chime in.

Have fun and be safe!

Not on topic but just curious, have you thought about a 9mm conversion barrel for softer shooting?

I've been using Accurate #2 with HiTech coated case bullets, both 124 and 147 grain. Manual puts them in the 1000-1100 FPS range.

quote:

Originally posted by huskerlrrp:
Not on topic but just curious, have you thought about a 9mm conversion barrel for softer shooting?

I'm heavily invested in .357 SIG (spare magazines, reloading dies, empty brass). I only have one 9mm pistol, and that is just because I feel everybody needs at least one, just in case.

You can download any cartridge with the right powders. Whether your stock gun will run those reduced loads is the question. I have loaded 100s of 1100fps loads in mine using Unique, but any medium burner in that range will work. You could go faster still but probably have to change a recoil sring to get 125/1000fps loads to run.

quote:

Not on topic but just curious, have you thought about a 9mm conversion barrel for softer shooting?

I run a 9mm conv bbl in my G32 for low recoil loads, works great. I did drop one spring rate but the stock spring seemed to run fine with 147gr @ 800fps.

I loaded some AA#9 below the starting weight with 147gr XTPs in my Glock 31C. I didn't have any problems with cycling, but I noticed some incompletely burned powder granules and a lot soot left in the barrel. I didn't have this problem running near max charges of AA#9.
I decided to just get a 9mm barrel from Lone Wolf for the lower recoil and cost of ammo. I'll save my reloading efforts for making fast 357 SIG loads.