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Discussion Starter #1
I'm considering loading .357 Sig, but not sure and was wondering if anyone has experience with that caliber. I have a lot of brass and it uses the same bullet as the 9mm that I already load.

I wonder if the case has to be treated like a necked down rifle case ie does the case need to be trimmed, and does the cartridge head space on the shoulder like a rifle round or on the lip like a 9mm or .40 S&W?

In looking over the .357 sig loading data in the Hornady book the max velocity for 115 gr bullet is 1,300 FPS. The 9mm, 115 gr max's out at 1,200 FPS. So does the extra 100 fps make the .357 more accurate than the 9mm?
 

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Not the SIG, but I do reload the .400 Cor-Bon, pretty much the same.
Compared to straight wall or tapered cases, it IS a PITA.
Basically, your correct in that all the same issues and procedures for necked rifle cases apply.
Headspace is set by the shoulder, therefore treat it as a standard shouldered rifle case. Some early reports on the .357 Sig had it headspacing on the case mouth, then the case mouth AND the shoulder, but the shoulder is most important, and that's where MOST reloading problems occur.
Dillon has a carbide die for it, but it still MUST be lubed, so I personally don't see the point.
The neck is short, so trim length and O.A.L. of the case is important.
That about sums up my experience, good luck and have fun.
 

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I'm considering loading .357 Sig, but not sure and was wondering if anyone has experience with that caliber. I have a lot of brass and it uses the same bullet as the 9mm that I already load.

I wonder if the case has to be treated like a necked down rifle case ie does the case need to be trimmed, and does the cartridge head space on the shoulder like a rifle round or on the lip like a 9mm or .40 S&W?

In looking over the .357 sig loading data in the Hornady book the max velocity for 115 gr bullet is 1,300 FPS. The 9mm, 115 gr max's out at 1,200 FPS. So does the extra 100 fps make the .357 more accurate than the 9mm?
i have reloaded for it, it was fun...

-headspaces off the shoulder
-you need to use .357 sig bullets as the 9mm are not hard enough and from what i remember have a slightly differently ogive geometry
-make sure you have a solid taper crimp, and don't expand the mouth too much as you need all the neck tension on the bullet that you can get
-don't use 0.40 S&W cases even though they can work, use .357 sig cases
-it was worth it to me to purchase a headspace gauge for this round to gain confidence in using the shoulder as the datum point

the 357 sig is supposed to provide .357 mag peformance in a semi auto, i couldn't get there with my Glock 23 drop in barrel but i am sure your genuine .357 Sig will do just fine... isn't it supposed to deliver a 125gr bullet at 1400 fps? supposed to be a flat shooter and good penetrator, it is the round that the Secret Service uses...
 

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Note: i have been reloading 357sig for about 5 years.

the easy way to size and deprime the case is to 1st use a 40 cal sizing die. that way you don't need to lube the cases as in rifle dies. then just neck size the neck.

the normal bullet is a 9mm flat nose bullet. it also helps to use a lee factory crimp die.

do a search via internet for 357sig forums. lot of info/.
 

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Discussion Starter #5
I was thinking about getting a drop in barrel for M&P .40, but if I have worry about case length & trimming I don't think I will. It's not worth the extra effort to me.

All three of my books (Hornady, Lyman, and Lee) give a max 125 gr velocity of about 1,300 fps using Blue dot. The max for power pistol, which is what I use, is about 1,250 fps.

I find a lot of once fired .357 sig at the pistol range where I shoot and there are several Federal, State, and local LEOs that shoot there so I suspect some of them are using the .357. One of them is the best pistol shot I've ever seen. Not sure who he works for he will only say he works for the Government. I watched him put 15 rapid fire rounds in a 2" bulls eye from 25 feet shooting one handed. He was using an M&P shooting .357 sig. That's what gave me the idea of loading .357.
 

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I reload the 357 Sig too. I own a set of the Dillon Carbide Dies. They do NOT require lube. I have loaded hundreds if not more without any lubing required. Only thier carbide rifle dies still require lube.

I have used regular 9mm bullets with great success. Getting bullets spcifically labeled for 357 Sig is not a must.

My SP2340 is my favorite pistol to shoot. If you decide to get into reloading, I believe I have an extra LEE crimp die laying around. Yours if you want it.
 

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I have loaded the .357 SIG for years. It is not a hard round to load at all. Do not try to form .357 SIG cases from .40 S&W because the overall case length will be too short. It is best to use a .355 dia bullet designed for the SIG cartridge because a lot of other 9MM bullets have too long an ogive. Also be sure to use a die that has a taper-crimp shoulder rather than a roll crimp. The cartridge is supposed to head-space on the case mouth...not the shoulder. So check the case length after resizing. I have only needed to trim cases once so far (I have reloaded some cases 10+ times). The Sig was designed around the 125 grain bullet as it was meant to duplicate the fed's standard 125 grain .357 magnum revolver load in a small frame auto. The Sig is a very efficient round and after a lot of testing, I settled on a 125 grain HP loaded over Blue Dot powder. The Sig has a lot better penetration than the .40 S&W so a good HP or SN bullet will transfer shock better than an FMJ. I really enjoy loading for and shooting my .357 SIG ....I am sure you will too......Hope this helps.......Don in SC
 
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