.40S&W cases into .357SIG?

[Argonnakid]

As the sig cases are priced higher than I like, does anyone have any history reshaping the .40S&W case to .357SIG. The way I look at it, it looks to be just creating a neck on the case. Is there a pitfall I'm missing. I'm looking to shoot one of my pistols cheaper than factory ammo will let me.

 

[Ivan the Butcher]

The 40 S&W case will be a little short if you get the neck right without collapsing the case. 10mm cases will be long enough but I think the web is even stronger. Just pony up the money and be done with it. I bought a 1000 new from Midway. When my buddies found out I was loading 357 Sig, I was given 3500 Plus a bunch of 10 round "Ban" magazines. I think you will see decent priced range brass appear when the "craziness" passes. Ivan

 

[Maximumbob54]

.40 cases end up too short and 10mm end up too long. I think they did that on purpose. Since they head space on the shoulder you can use the .40 cases if you can get the bullets crimped well enough. There are places that sell the cases once fired and you can pretty much reload them until they split so chase them down when they go flying.

 

[Jellybean]

If you use the 10mm, can't you trim them to length? Or are they priced the same as the .357 sigs?

 

[rwsmith]

Look at...

I don't have it in front of me but I THINK I read something about case wall thickness being a problem.

 

[SMSgt]

Two old geezers I shoot with (both ex-machinists) shoot nothing but converted .40s in their .357s. They don't seem to have a problem despite the shorter neck.

 

[S&W1006]

The 40's are too short and remember the 10mm uses large primers and the 357 sig and 40 use small. I don't know if it would make a big difference either way.

 

[colt_saa]

40 cases reformed to 357SIG will work fine providing you have enough neck tension since the resulting case neck is about .1" short.

This means heavier projectiles as opposed to lightweight ones.

Get the idea of using 10MM cases out of your head. Even if you trim them prior to forming the thicker web and walls of the 10MM cartridge reduce case capacity so all of your loads need to be reworked. A safe load in a 40 formed case can be significantly overpressure in a 10MM formed case.

Additional as you were to acquire 357SIG brass you would need to keep them segregated because of the two different primer requirements.

 

[fredj338]

There really is no point. The slight cost diff for once fired 357sig is negligable compared to the down side of an even shorter neck & thinner case when forming from a 40. Yes it can be done, but no reason.

 

[Jellybean]

I have quite a few .40 cases and a good number of 10mms too. If someone were to drop a .357 sig in my lap, I'm sure either one would work. Short necks or thick walls with large primers? I guess how much of a bother it is depends on the individual.

 

[jepp2]

GB has a page full of once fired 357 Sig brass at reasonable prices. The short neck is enough of an issue to deal with when using the proper brass, why further complicate it by using the shorter neck with the reformed 40 brass?

 

[Rule3]

Search for once fired bras. At about $45 for 500 is it worth messing with?

Starline states it can not be formed from the 40 SW.

https://www.starlinebrass.com/brass-cases/357-SIG-Brass/index.cfm

"Cannot be formed out of .40 S&W."

 

[rwsmith]

I don't understand

Search for once fired bras. At about $45 for 500 is it worth messing with?

Starline states it can not be formed from the 40 SW.

https://www.starlinebrass.com/brass-cases/357-SIG-Brass/index.cfm

"Cannot be formed out of .40 S&W."

It starts off saying that the .357 Sig is a necked down .40 S&W. Then it says they can't be formed from the .40?????

 

[Rule3]

It starts off saying that the .357 Sig is a necked down .40 S&W. Then it says they can't be formed from the .40?????

The "parent case" was the 40 SW but as posted by others it's a tad to short. I just post the news they wrote it. Do a search the Sig was designed as what it is, It is a stronger case (web). It's not worth trying to save a few dollars.

Regardless it's cheap to buy them already made ,and with the correct head stamp even.

I picked up a funny looking 223 Rem the other day, it was of course a 300 Blackout. So someone took the time and effort to bandsaw off most of it reform it, trim it to length resize again. I guess if you like doing that stuff.

 

[geddylee10002000]

I have about 750 - 800 mixed that I would part with. Once fired. You could look up online retailers. About 6 cents each. PM me if interested.