357 SIG headspacing

[armyfazer]

I am a noob to reloading. I managed to reload 45 ACP with no damage to me or surrounding areas and am now branching out to 357 SIG.

I see posts referring to headspacing off of the shoulder or the mouth of the case. Can someone go Barney style on me and explain what this difference means?

I haven't reloaded rifle cartridges yet, so I this will be my first experience with bottlenecked cartridges.

To get my feet wet, I plan to use 10 gr Accur #7, 124 gr xtp with CCI #500 small pistol primers. This is readily available locally, so I will buy this in small batches to get going. And I am using the Lee 4 hole turret press.

I have been doing a ton of reading here and on other forums. Any tips or info is greatly appreciated.

Cheers,
Richard

 

[Walkalong]

For a caliber that headspaces off the case mouth the length of the case determines how much headspace there is. For a caliber that headspaces off the shoulder how far the datum line on the shoulder is from the base of the case determines headspace. (Assuming properly machined chambers)

Something has to stop the brass going forward when chambered. How much extra space is left (wiggle room front to back) is how much working headspace we now have.

For the .40 S&W the case mouth stops the case.

For the .38 Spl. the rim stops the brass.

For bottlenecked caliber (except for belted cases) the shoulder stops the case. This is why sizing bottlenecked brass is so much more critical than a straight walled case.

For belted cases the belt stops the brass, although many people size so that the shoulder does.

 

[JimKirk]

The 357 SIG is said to headspace off of the case mouth... but I've found that the shoulder has "more effect" as far as headspacing than the case mouth. I guess that you could say it uses both. I use the chamber of my Glock 31 as a headspace gauge... if it fits my chamber like it should ...then I'm good to go. Others are going to tell you to buy a headspace gauge...

If you can get your hands on some AA # 9 ... you'll love it in the 357 Sig.

Jimmy K

 

[armyfazer]

Thanks for the info guys. There is so much to learn. Kind of makes me want to stick with 40 and 45. But I don't wanna give up!

 

[918v]

The .357 headspaces off the case mouth but only when using new brass. Once resized, the case headspaces off the shoulder.

 

[JimKirk]

Once you have your sizing die properly set for your gun... there should be very few other problems to reloading the 357 SIG.

Here are a few other areas to watch for....

Proper neck tension ... the 357 has a very short case neck. It needs all the neck tension it can get.

Seating bullets ... make sure they enter the case mouth square... if they tip much at all they will not chamber correctly.

Use a powder that fills the case... this helps with bullet set back.


Once you get everything working like it should ... the 357 SIG is an enjoyable round to shoot ... mine is way more accurate than I can hold...

Go ahead ...jump in ...the water is fine!

Jimmy K

 

[Bubba613]

Lots of wrong info given on the Sig round. Read up and go from there.

http://www.realguns.com/Commentary/comar65.htm

http://www.realguns.com/archives/112.htm

 

[ReloaderFred]

The subject of loading for the 357 Sig seems to come up every few months. A search will reveal several different threads on the subject.

I've loaded many, many thousands of rounds in this caliber. Without looking up the exact numbers, I would say somewhere around 14,000 rounds.

It's an easy round to load, if you pay attention to what's going on, and once set up, it goes smoothly. There's really no mystery about the round at all.

I've found that there are actually two datum points, no matter what anyone else says. The primary datum point is the case shoulder, with the secondary datum point the case mouth. I can guarantee that if either datum point is ignored, and the loaded round is beyond spec., the round won't chamber. If the shoulder isn't set back far enough, or if the case is too long, then the result is a round that won't fit in the chamber. I've had to trim some Federal nickel brass that was too long, and that's a pain with such a short case. I also had the problem of shell holders being too thick to allow setting the shoulder back enough and I had to mill off the top of the shell holder to allow the case to be pushed far enough into the sizing die. I did this in 2002, when I bought my first 357 Sig, a Springfield XD. I now own three 357 Sig pistols.

The only company I'm aware of that makes a case gauge for the 357 Sig is Wilson, and it's a case gauge, not a loaded cartridge gauge, and it only works with sized cases. Most people would be just as well served by using the barrel of their pistol for a case gauge, but please remove it from the firearm first........

Dillon makes a carbide sizing die for 357 Sig, and I have their set. Don't waste your money. I also have a Redding die set in this caliber and I use a combination of the two to load this round, but either Redding or RCBS dies will serve you well with loading this caliber.

Hope this helps.

Fred