I am attempting to load .357 SIG for the first time. I have IMR 800x powder I'll be using, plus Nosler 124gr bullets. I have the Hornady #9, and the Internet. Using those, I have found only one load from IMR with a Speer bullet. It only lists a maximum charge of 10.0gr compressed. I would sure like to see some other data for this. Is there any other published data for 800x in a .357 SIG?

Also, I use a Forster Co-ax. I bought RCBS dies. It seems I can not adjust the die down far enough for the shoulder to get pushed back. So, is it ok to use without pushing the neck back? I plunked them in my Sig barrel, and they are just barely above the rearmost part of the barrel. Factory ammo is just barely below it. I closed a resized case in the gun, and it closes properly. I only own one .357 SIG, and the cases are all mine, but I do find this a little annoying even if it will work for me.

Because the die doesn't adjust down, it also does not expand the case mouth, though I'm not sure the die does that anyway. I tried seating a bullet, and it goes in, though it is tough at first. I'm a little concerned about buckling a case, so I will buy a tool to chamfer the neck. I think this is ok, but just putting it out there. The bullet I seated partially was hard as hell to remove, so I'm less concerned about setback than I thought I'd be.

The seating die also does not adjust down all the way. It doesn't matter for OAL, but it means that the crimp part of the die never touches the case neck. Since it's not being flared I tend to think that is not a problem. Thoughts?

You could NOT have chosen a more difficult handgun caliber to learn how to reload with.

1) Don't do anything more until you get a case gage for 357 Sig. Lyman an L.E. Wilson both make excellent case gages and they can be purchased from either Midway or Brownell's. As for your "plunk" test, the 357 Sig is just too "touchy" to use workarounds with.

2) Sizing Die. Start out with the sizing die screwed in far enough that you can just feel the toggle starting to work when you close the ram without a shell in place. If that won't set the shoulder back far enough to allow the case to gage properly you need to call RCBS about a defective die. BTW, I bet the die was made properly, you just didn't understand the instructions, touching means touching to the point where you can actually feel it when you close the press empty.

3) Flaring die. Bring it down until it touches (see above), back it out 1/2 to 1 turn and lock the die in that position. Next, loosen the lock nut on the flaring plug and Unscrew it a bit. Lift an empty sized case so the press is fully closed. Now hold the lock nut for the flaring plug and turn the flaring plug down while preventing the lock nut from turning. When you feel the flaring plug touch the empty casing use a sharpie and make a mark on the top of the flaring plug center out going away from your body. Now lower the press and turn the flaring plug down 3/4 turn and finger tighten the lock nut. Test flare that case and measure the diameter of the flared opening. I prefer to set my flaring die up to flare the end of the case so that it's about 0.005 inch larger than a case fresh out of the sizing die.

Note, if you don't have any calipers those are also available from Midway or Brownell's, so get some. BTW, don't tell my they are too expensive, a Lyman Digital Caliper costs less than one single box of 357 Sig. The same applies to a proper case gage.

4) Crimping. If I were to try and describe how to properly set up a combined seat/crimp die it would span more words that permitted in a post. After all that you would then find that you will probably need to trim all of your cases to length to get a good crimp. I would STRONGLY urge your to purchase a second crimp die so you can seat and crimp in separate operations. BTW, unscrew or remove the seating plug from an RCBS Seat/Crimp die and you have a Crimp Only Die. Screw the seating plug further in an identical Seat/Crimp die and you have a Seating Only Die.

Scooter is spot on with learning to reload on 357sig... Better yet, get a .40 cal barrel for your gun and learn to reload those first.

I have been reloading the .357 Sigs for about a year I admit it takes a while to get it right Collect all the info you can and go to it. I use Lee exclusively and never had any problems, well just one , the priming system but I solved that by hand loading.

And I bet you don't own a Forster press, or understand how it's different from a single stage press with a ram. And apparently you don't have the RCBS dies for .357 SIG, or you'd know it's a two-die set, so there is no flaring/expander die to set up. Thanks for the generic instructions and the dressing down, though. And I never suggested the die was at fault (or that calipers were too expensive, or that this is my first time reloading....)

I will look into getting a case gauge, it seems that would be a useful tool in this application. I'd also happily buy another reloading book, but only if I knew it had .357 SIG data with 800x powder in it, which is why I'm asking if anyone knows of one.

Wish I could offer suggestions but I'd have to see your set up. Being a bottleneck cartridge, reloading the .357 SIG should be similar to reloading a bottleneck rifle round, only on a mini basis.

I checked the Hodgdon's site for 800x data and they list that powder for a 125 grain bullets, but only one powder load.

If I were you, I'd make a couple of dummy rounds and ensure they feed and chamber okay in your gun. If so, try loading a "few" rounds and trying them. As long as the action is locking up correctly, you should be okay.

Yeah, that's the only data I have seen also. Just one load, the max... It's better than no load data, but I'd really like to find another source just for comparison/sanity.

Once I chamfer the cases, I can make up a few dummy rounds. I'm a little concerned about ruining some if I seat bullets now. But good idea. I would prefer them be sized "properly" so they'll work in any gun, but in reality they will only be shot through mine.

I did alot of research before beginning to load this round. I bought a .40 cal carbide die to size the case body. Then use the RCBS sizing die to resize neck/shoulder without needing case lube. Chamfer the inside of the case neck to permit easier bulletseating. You need a very tight fit because the case neck is so short, I have not belled the case mouths. Have not crimped either because if you over do the crimp it can actually loosen the tension. I think I have seen other info on 800X and will check this evening. I did buy a case gage also because the headspace is very important with this round and it is nice to plop the sized case in the gage to insure everything is good. There is some Nosler load data, two separate pages for 115 and one for 124 grain Nosler hp's but I can not remember if 800X was one of the powders.

Yeah, the .40 S&W die is a trick I will consider if I start reloading it more. I didn't initially want to buy a ton of stuff without knowing how it would go.

I have looked at the free data from Nosler's website, and 800x was unfortunately not one of the powders they listed for the 115 or 124gr bullets in this cartridge. I do not have their book though, so perhaps they have the data available just not free. I'd be happy to buy it if that's the case. Thanks!

Unfortunately, you have the wrong dies IMO. RCBS got the 357sig all wrong. No expander, you can't load plated or lead & jacketed can be dicey with bullets like the xtp. RCBS also got the shoulder placement wrong, sticking with the idea the rd headspaces on the case mouth & that just isn't possible with most guns. Every other manuf got it right with 3 die sets & proper sizing die that allows head spacing on the small shoulder.
Not all is lost. You can buy an expander/flare die or use a powder thru like the Lee. Grind off some of the shell holder &/or bottom of the die until you get proper headspace. Me, I would sell the dies & buy Hornady or lee if you are trying to save some $$. Dillon are terrific, only carbide sizer available, but you still need a flare die to do it right. More data, load books jst for 357sig.
http://www.midwayusa.com/product/955...ProductFinding

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Yeah, I guess I will have to get different dies. I sort of knew that, but was hoping maybe I could avoid it. I'm sure I could make ammo that worked with the RCBS, but I'd prefer something that I have control over the shoulder with.

I have experience with Lee and Redding dies. I like Redding dies a lot, especially their neck sizing expander (though Lyman and RCBS apparently have the same thing). Is there anything bad about Redding's .357 SIG dies? Will I likely have some leeway with where the shoulder is even with the thick shell plate of the Forster press?

Thanks!

Other than not being carbide, Redding are great. If you have access to a grinding outfit, like an auto or gun shop, they can take 0.010" off the bottom of a steel die easily enough. Then you just need an expander die.

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Groo here
Bullet set back is a problem with the 357sig.
Many use AA9 powder as it will fill the case and support the bullet.
The trick of the 40 sizing die is well known in the SIG circles.
The manuals will confuse you about head spacing.
The 357sig DOES headspace on the sholder so turning the
case mouth in against the bullet to stop setback is OK.
Just be sure you set the sholder back far enough to set the headspace
to your barrel.

The 40 carbide/357 neck & shoulder sizing trick really speeds things up on a progressive press. Lee dies are cheap but effective.
Seat bullets and crimp as two separate steps.
Lee's 357 Sig Factory Crimp die is the best, bar none, for this cartridge. It totally eliminates collapsed shoulders.
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If you are getting collapsed shoulder, you are doing something wrong. Generally you are not belling the case mouth enough or over crimping.

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The 49th Edition of the Lyman Reloading Handbook list's
800x with a 125gr Speer Gold Dot Jacketed at 1.135OAL
8.5 suggested starting grains
9.5 max load grains

Every collapsed case I've ever had was from over crimping.

I have reloaded the 357 sig and I want you to know about bullet setback. I now use bullets from montana gold that are made for the 357 sig. Both the right bullet and powder that fills the case will stop setback. To test for setback just cylcle the gun with your reloads. Then look for pushed in bullets. Try pressing on the bullet to push it in. If it moves, Dont use those loads.

For closure, Redding dies work with the Forster press and the case goes in enough to set the shoulder back.

I shot my first .357 Sig reloads, though have not chronographed them. 8.0 and 8.5 grains of 800x under a 124gr Nosler. I was surprised by how full the case was with 8.5 grains. I brought Remington FMJ along as a comparison, I couldn't really tell a difference with 8.5 grains vs the factory, but 8.0 was a little softer. It cycled well though.

I will chronograph them before I go further with the load though. I just didn't have time to bring it along.

For some further closure, 8.5gr of 800x under a Nosler 124gr bullet from a 3.9" SP2340:

1264 FPS, SD: 10 with 5 rounds tested

So I will work up a bit closer to the listed max from here. But they seem to shoot well and are 7" steel at 30 yards offhand accurate. Unless they turn into laser beams though, I'm pretty satisfied with the 8.5gr load. It's not burning it up, but it's about the same velocity as Rem UMC stuff.

When I first started loading for the Sig, I found this series of write-ups to be very helpful. The link takes you to the first of 4 articles.

I only load jacketed bullets (always use Montana Gold) and don't expand the case mouth at all. I do chamfer the inside of the neck and use the Redding competition bullet seating die. It provides excellent bullet alignment with the case mouth. The die isn't cheap, but I don't have any issues with setback. The seating die can be found here.

This thread is quite timely to say the least-- I have yet to load for the 357 SIG, but hopefully I have all I need. I have Dillion dies as they are carbide but will give the extra 40 die some thought-- this will be somewhat of a Winter project -- I cannot seem to find a CASE HOLDER for the SIG using my new Sinclair version of Wilsons Trimmer--but I believe the one for the 40 will do nicely-- been putting this off but the whole kit was on sale so I went for it-- I did not realize the 'hold down clamp' was included-- a rea; plus when it arrived today. I will say this trimmer is the RR of trimmers, especially with the upgraded handle-- THANKS to all for the information-- I will be watching this real close.

Yes the 40, 10mm & 357sig share the same case head.
If you have the Dillon dies, you don't need to bother with the 40 sizer, just adds another step. I polished the powder thru expander down 0.001" to bell more than expand. Seems to help neck tension quite a bit.

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Or the case is a touch too long to begin with!