Forming 357 Sig from 40 S&W

[damndirtyape]

I'm ordering a 357 conversion bbl for my G20 slide which I'm putting on my 21SF (Holy frankengun, Batman). The only real purpose behind this is to use cheap 9mm bullets in my favorite handgun.

Anyways, I have a few thousand 40 S&W cases that followed me home, despite not having a gun 40. Forming these to 357 would be a lot cheaper than buying once-fired 357 or firing factory 357 myself. No-one at my range shoots 357, so no free brass in this caliber.

Problems to consider with forming 40 into 357:
1. The formed 40 case will be shorter than 357 case, some manuals say 357 headspaces on the mouth.
Solution: Ensure I size the cases so they headspace on the shoulder in my barrel.

2. 357 SAAMI max is 40k psi, 40 is 35k.
Solution: Don't load to max. Interestingly, all the data on data.hodgdon.com maxes out below 35k psi, so this should be fairly easy. Stay on the low side just to be safe.

3. The neck on a formed 40 is shorter than on a real 357 Sig, exacerbating bullet tension problems and making bullet setback more likely.
Solution: Be darn sure I'm flaring, crimping, etc. properly. Lots of function testing to test for setback. Going extreme may include sanding/polishing the neck expander to keep the necks tight.

Anyone else tried this? Any potential problems I'm missing here?

Thought I'd check with you guys before my CRBness gets the better of me. :chicken:

[Tailgunner]

I'd suggest starting with 40 Mag (10mm Auto) brass instead of the 40 Spl (10mm Short) brass

[ISUSteve]

I'd suggest starting with 40 Mag (10mm Auto) brass instead of the 40 Spl (10mm Short) brass

Then you have to use large primers instead of small primers.

[4eyes]

Buy a Dillon dual carbide ring sizing die so you don't have to lube the cases prior to reforming. Die setup for the short neck is the same as for the longer neck; dies must be adjusted for each length. Most 9mm bullets have too long an ogive/nose to work in 357 Sig. Crimped on the bearing surface-they won't go in the mag in standard Glocks--they may fit in the longer G20/21 mags.

[damndirtyape]

Buy a Dillon dual carbide ring sizing die so you don't have to lube the cases prior to reforming.

Is that just the regular Dillon 357 SIG carbide sizing die?


http://upload.wikimedia.org/wikipedia/en/7/78/357Sig10mm40sw.jpg

Looks like there should be tons of room for seating the 357 long in a G20 mag, comparing the 10mm in the middle.

[Steve Koski]

Lots of folks have used 40 brass for .357 Sig successfully. It seems that correct bullet profile has more to do with reloading the Sig than anything else. Many 9mm bullets don't work well.

[ISUSteve]

You shoulda got the GAP.

[MakeMineaP99]

Check Montana Gold for .357 Auto specific bullets.

[Steve Koski]

Dat's right. Lots of folks like them MG's in their 35 caliber Siggies.

[4eyes]

Talk with Dillon. Mine is their regular sizing die. Get control of your gasp reflex; they are expensive. And work flawlessly.

[creophus]

Maybe you should just get a 40s&w barrel and shoot lead through it. Might be cheaper than buying 357 sig bullets.

[damndirtyape]

Maybe you should just get a 40s&w barrel and shoot lead through it. Might be cheaper than buying 357 sig bullets.

I shoot at an indoor range. While there is good ventilation, I try to minimize the amount of lead I shoot.

[creophus]

Well how about Rainier or Berry plated bullets in 40?

[MakeMineaP99]

Plated is the same price as jacketed these days.

[damndirtyape]

Well how about Rainier or Berry plated bullets in 40?

Up here in The Great White North we don't have the same broad bullet selection you 'Mericans have.:) The only plated bullets I've found up here weren't very round and inconsistent in both weight and diameter. We got a guy in AB who imports MGB tonnes at a time, so that's almost all I use for handgun.

[187racing]

brassman.com used to have sig brass $30/1K mixed. I bought a bunch and have been happy with it. It's been mostly speer lately. Might be easier than making your own. Time=money and i'd part with 30 bucks rather than spend hours making my own.
The 10mm brass idea works, although all reloading data is now useless due to the large primers. I suppose you could work some up and see how they shoot.
I've been using speer 115 flat point 9mm bullets in my 357sig loads and they work well. The round nose/NATO type bullets don't work due to the length. If you seat them to the correct OAL, then the bullet will just push into the case no matter how hard you crimp it. I tried a couple to where they would crimp, but they wouldn't fit into the mag. Didn't try them in the chamber.
I would sell the 40 brass and use the $$ to buy the sig brass and just load em up!
Good luck!

[Oreo]

I'll trade sig brass for .40 brass.

I can't imagine wasting 10mm brass by turning it into sig brass. It's worth more as 10mm. Trade it (TO ME) for sig brass, or sell it & buy sig brass. Sig brass is pretty common. At least around here anyway.

[chewy]

I can't offer too much. But i reformed a 40 S&W case to a 357 Sig pretty easily out of curiosity. In my 357 Sig Lone Wolf barrel it seemed to seat on the shoulder as there was no difference between real 357 Sig resized brass. Just be careful to not max load em.

[damndirtyape]

Dies and barrel showed up and I had a few 147s lying around, thought some may be interested in results so far. I'll eventually be loading 124s or 115s when I bother to buy some.

http://img98.imageshack.us/img98/1830/dsc03548gh4.jpg

Left: The G20 mags allow you to load loooong, way longer than the barrel will accept.

Lubing the cases is recommended if you don't want an imprint of the ram in the headstamp. About half the cases end up with a crescent of brass just above the extractor groove (center). Some are thick enough to prevent completely chambering and thin enough such that the firing pin still drops. :yikes: This being a recipe for an OOB firing, I tried resizing the cases with a 10mm die first, then into the 357 die. Presto! No ring forms (and no lube required either). There are advantages to having dies for a caliber you don't shoot. :slick:

Right: Gold Dots cost a dollar each. I can't bring myself to shoot the other 10 in the box. I'm glad I reload.

[damndirtyape]

Regular 124s can be loaded to 1.27 and they still fit the mag and bbl. Any longer and the bullet won't traverse the entire neck and probably cause setback problems. As-is, 10 chamberings shrink 'em about 0.035. I wonder how much more powder I can safely put in with the huge OAL increase. Maybe I can get to 357 Sig velocities after all! :17:

http://img403.imageshack.us/img403/4337/dsc03551ws2.jpg

[ept000]

You can always fire-form 9mm brass into .357 Sig. I have seen it done.... by a freakin idiot!
http://farm4.static.flickr.com/3107/2626168361_53f54f26ba.jpg

http://farm4.static.flickr.com/3114/2626168577_21a56e8958.jpg

He actually gave me the brass so I could reload it! :yikes:

[chewy]

You can always fire-form 9mm brass into .357 Sig. I have seen it done.... by a freakin idiot!
http://farm4.static.flickr.com/3107/2626168361_53f54f26ba.jpg

http://farm4.static.flickr.com/3114/2626168577_21a56e8958.jpg

He actually gave me the brass so I could reload it! :yikes:

Sounds like he deserves to have it reloaded and given back to him to shoot. :ow:We need a K-Boom smilie.

[ept000]

I can't believe the thing kept on shooting!
http://farm4.static.flickr.com/3002/2626986256_3027fcaab4.jpg

[MakeMineaP99]

Was this the guy who told you he could use 9mm or .40 in his .357 Auto?

[ept000]

Was this the guy who told you he could use 9mm or .40 in his .357 Auto?
Yep. And to some degree, he was right. If someone had asked me if they could shoot 9mm out of a 357 Sig, of course I would say "no way". And clearly I would be wrong, because this dork shot hundreds of them! And lived to tell about it!


Darwin was wrong....

[MakeMineaP99]

Don't let this guy start reloading. He'd fill the case full of Bullseye, level it off and then seat a bullet. Whoops.

[ept000]

Don't let this guy start reloading. He'd fill the case full of Bullseye, level it off and then seat a bullet. Whoops.
This same guy has been shooting reloads that he got from a guy that had to sell all of his stuff due to a recent conflict with the law. I took a few of the reloads and pulled them apart and the fist thing I noticed is there is no lube in the lube grooves. None. I told him not to shoot them, but I'm sure you guessed he went ahead and did it anyways. He told me the other day his gun cracked. He said it felt like it exploded in his hand and when they took it apart it had a crack in the frame. I haven't seen it yet, and probably won't, but I don't know how to help someone this stupid. He was all upset because this was his favorite gun. He got a little pissy when I said, "what did you think I meant when I said DON'T shoot those reloads?". Dumbass....

[MakeMineaP99]

You're hanging out with a rough crowd.

[ept000]

You're hanging out with a rough crowd.
When I graduated high school I was something like number 329 out of over six hundred students. I figured that was cool because I could find those 328 other people and hang out. I could be the leader. Well, this is where that theory has gotten me. Trying to keep people from killing themselves with stupidity. Yanking people up the food chain is tougher than it sounds.

[creophus]

This same guy has been shooting reloads that he got from a guy that had to sell all of his stuff due to a recent conflict with the law. I took a few of the reloads and pulled them apart and the fist thing I noticed is there is no lube in the lube grooves. None. I told him not to shoot them, but I'm sure you guessed he went ahead and did it anyways. He told me the other day his gun cracked. He said it felt like it exploded in his hand and when they took it apart it had a crack in the frame. I haven't seen it yet, and probably won't, but I don't know how to help someone this stupid. He was all upset because this was his favorite gun. He got a little pissy when I said, "what did you think I meant when I said DON'T shoot those reloads?". Dumbass....
Bad news! Someone gave me some ammo he found over the years of shooting at the range. I thanked him and accepted them, but there is NO WAY I'm gonna shoot that stuff. I have NO CLUE of knowing where it's been!

Sounds like the guy you mentioned has a guardian angel that is working over time!!