Tips and cautions for loading .357 SIG

[Lennyjoe]

Figured I’d give the .357 SIG a go and decided to convert a G27 from .40 to the SIG using a G33 aftermarket barrel. That being said, I’ve reloaded going on 20 years now and thought I’d ask some of you other seasoned vets on any up front tips or cautions for loading this bottle neck pistol cartridge.

I have some RCBS dies, Starline brass and 500 Montana Gold 125 grain .355 JHP bullets on the way to start with. Bullet availability is scarce so I grabbed what I could to start. I have plenty of different powder options but thought I’d start with AA#9.

Of course I did the good old THR search for .357 SIG here for some homework and found some decent data. Any other help will be much appreciated. Thanks in advance.

 

[JimKirk]

AA#9 is a good starting powder.... and a good all around powder.

I am shooting a bunch Long shot in my 31

HS6 is good medium powder ...

Be careful seating bullets as it is easy to crush the shoulders...

 

[Lennyjoe]

I have Longshot I use for .40 and 9MM so maybe I’ll see how that runs so I can limit powders. I also have a lb of HS-6 gathering dust in the powder cabinet as well.

 

[WrongHanded]

Try to minimize the flare to the case mouth prior to seating. There's not much neck, so you'll want to keep as much of that tension as you can. I've accidentally over flared before and even a firm crimp with a FCD didn't stop setback with just strong thumb pressure.

Honestly, that's the biggest issue I've had.

I like Power Pistol and BE-86. Haven't tried any other powders yet. RMR's 124gr FMJ truncated flat point bullet will work for .357 Sig, loaded to 1.140" OAL. This bullet with 8.7gr of PP and a CCI 500 primer is my range load. It runs at 1425fps out of a 4" barrel, and is really pretty accurate. Anyhow, that bullet will work for you too. I really should try some Montana Gold.

 

[wbbh]

I load .357 SIG using Lee dies, they work just fine. Knock on wood, I haven't had a problem with the tapered cases. I use sizing lube, usually lanolin and alcohol, then tumble the brass with corncob media to remove the lubricant.

My pistols all like 124 grain RMR hollow points. For powder, I've had good luck with CFE Pistol, True Blue but my goto is Shooters World Ultimate Pistol.

I use the a combination seat and crimp to only seat, I use a Lee Factory Crimp die to lightly crimp just enough to remove the bell from the mouth of the case. This method avoids any downward pressure on the case and resulting bulge.

 

[JimKirk]

One the best things I found for the 357 SIG is the Redding GR-x die ...it is made for the 10 mm Auto ....it is simply a push through die that sizes the brass body to normal size ....works for 357 SIG ....shove the brass through and it brings the straight body back in specs. The SIG is not a tapered case .... . Then run the brass a 357 SIG die ..... I use the lanolin mix lube in a gallon Ziploc bag ....couple sprays ....roll brass around ....push through the GR-x die and again though the SIG die ...no need to relube.....

Both those dies are steel and need lube ....I think they do make a carbide dies..... for those that don't mind spending the $$$...

 

[WrongHanded]

One the best things I found for the 357 SIG is the Redding GR-x die ...it is made for the 10 mm Auto ....it is simply a push through die that sizes the brass body to normal size ....works for 357 SIG ....shove the brass through and it brings the straight body back in specs. The SIG is not a tapered case .... . Then run the brass a 357 SIG die ..... I use the lanolin mix lube in a gallon Ziploc bag ....couple sprays ....roll brass around ....push through the GR-x die and again though the SIG die ...no need to relube.....

Both those dies are steel and need lube ....I think they do make a carbide dies..... for those that don't mind spending the $$$...

Jim, why resize the body first with a 10mm die, if you're still going to use the .357 Sig die? What's the advantage there?

 

[AJC1]

Jim, why resize the body first with a 10mm die, if you're still going to use the .357 Sig die? What's the advantage there?

It would fix the bases back to spec. That's the only reason for a pass through.

 

[748]

It's not forgiving like 45acp. Watch seating depth and don't hot load it

 

[Blue68f100]

Figured I’d give the .357 SIG a go and decided to convert a G27 from .40 to the SIG using a G33 aftermarket barrel. That being said, I’ve reloaded going on 20 years now and thought I’d ask some of you other seasoned vets on any up front tips or cautions for loading this bottle neck pistol cartridge.

I have some RCBS dies, Starline brass and 500 Montana Gold 125 grain .355 JHP bullets on the way to start with. Bullet availability is scarce so I grabbed what I could to start. I have plenty of different powder options but thought I’d start with AA#9.

Of course I did the good old THR search for .357 SIG here for some homework and found some decent data. Any other help will be much appreciated. Thanks in advance.

40 cal brass re-sized to 357sig will be too short and you will give up precious neck tension. Use 357sig brass.

 

[FROGO207]

I use Lee dies and some brass has smaller flash holes and the decapping pin will get stuck in it. Also I use the Lee bulge buster to pre size my brass and it is much easier to resize in the SIG die after. I check each round for setback issues every time.

 

[Chuck R.]

I went for broke and bought the Dillon carbide .357S dies. Zero issues with neck tension, with a slight bell.

Some guys use .40 carbide dies, then run into a .357S sizer to be able to skip lubing brass. I just polish my brass well and run it into the carbide .357S die.

I'm also loading using LongShot, it's a fast powder in the .357S, I actually backed mine down some as I'm duplicating the Speer .357S GDHP loads that I carry. I agree with the other guys, there's plenty of 357S brass available, so don't bother screwing around with necking down .40.

 

[packetloss]

I also have the Dillon dies. I ran all my cases through a .40 carbide die first and did not need to lube at all. I set to bell at .382 which was the bare minimum for the bullet to fit in. Some folks were recommending to instead not bell but chamfer but I don't see that working out well and you would just end up with some crushed shoulders.

 

[kcofohio]

While we are on the topic of 357 SIG, has anyone used cast hi-tec coated bullets? If so, what has been your experience with them? Is there a certain mold that cast the best bullet for the cartridge?

 

[JimKirk]

Jim, why resize the body first with a 10mm die, if you're still going to use the .357 Sig die? What's the advantage there?

Late getting back to this ... The Redding 40 S&W G-Rx dies remove any "glocked" bulges ....(I have seen more other brands gun bulge brass than Glock) ...also removed any dings in the rim diameter .... Since it is a push through die ....I can body size really fast ....

Some folks are it as unnecessary to do so ...but I have never had a failure to chamber since using this sizing die....

Also makes sizing in the 357 SIG die a breeze.... since it only sizes the neck ...

 

[Lennyjoe]

40 cal brass re-sized to 357sig will be too short and you will give up precious neck tension. Use 357sig brass

Never had intentions of resizing .40 cal brass. I’m converting a G27 .40 cal to 357 SIG by barrel swap.

 

[mdi]

I've been looking at the 357 Sig for a while and saw mention of a Lee crimp die. I went to the Lee site and it does not say what type of die it is. Because I reload for every cartridge I shoot, I'm wondering if it is a collet crimp, post crimp sizing, roll or taper crimp die?

 

[Lennyjoe]

I’m gonna use the Factory Crimp Die.

 

[WrongHanded]

I've been looking at the 357 Sig for a while and saw mention of a Lee crimp die. I went to the Lee site and it does not say what type of die it is. Because I reload for every cartridge I shoot, I'm wondering if it is a collet crimp, post crimp sizing, roll or taper crimp die?

I'm pretty sure it's a collet crimp die (assuming my terminology is correct). And I think the reason it has a cap on the top is because bullets for .357 Sig are short and so don't protrude from the top of the die, unlike the collet crimp die I have for .45-70 as an example.

 

[cfullgraf]

As said, with 357 Sig, neck tension is the key. Also, no amount of crimp will make up for lack of neck tension.

Once you get the neck tension right, I find 357 Sig is no more difficult to load than other handgun cartridges. The extra step of lubricating the cases for sizing just consumes some extra time.

The only range brass left where I shoot, is what I generate so some of the issues caused by other guns does not effect me.

 

[JimKirk]

As cfullgraf said .... Not much neck on the 357 SIG to start with ....preserve all the neck tension you can to hold the bullet ... I don't flare at all and chamfer the brass slightly .... seating can be tricky but once you get it figured out.... makes some nice shooting ammo...

 

[Bottom Gun]

I’ve had my best results when I don’t flare or crimp the case mouth. I only chamfer the mouth. I’ve found doing that gives me the most neck tension and I have never crushed or deformed a case.

If you’re concerned about bullet setback, a slower powder like AA#9 will fill the case and prevent some of it.

I’ve never had bullet setback when I use the above method even when I use faster powders with lower volume like Bullseye.

 

[gojones]

When I started loading 357 sig, I found lots of good advise on this site. I use the 147 gn HPBT from Hornady, everglades and RMR. The RMR is a flat based bullet and I do expand to the min. the others are boat tailed and fit nicely w/o flaring. I use both WFS and BE-86 for this weight. Around 2k shot so far and no issues. I do crimp minimally though. I run through the Redding carbide dual ring sizer for 40 cal and then RCBS FL size without lube. I am using Speer pulled cases. This is a fun round to shoot and is very accurate for my abilities.

 

[FROGO207]

When I started I had few SIG cases so being cheap I sized 40 S&W cases down. After messing with them for about a month and not getting sufficent neck tension I scrapped that brass and bought factory ammo to shoot so I could retrieve the SIG brass to reload. And yes getting a propellant that fills the case does help with setback as well.

 

[JimKirk]

The 357 SIG neck is only 0.066" long to begin with . ... my experiment of necking .40 S&W down left the neck at 0.056" . ...sometimes less depending on the brand of .40 brass .... That means that 1/6 of the neck is missing .....that is too important on this cartridge....

Never the less ....I did shoot a few necked down .40 brass .... they shot ..... that was a fruitlessly experience.....

Too many 357 SIG brass out there ... I found a good supply of Winchester brass ....only problem is the small primer firing channel made sticking deprimer pins .... chucked up in a drill and 600 grit wet/dry solved that....