Loading/Reloading 357 Sig

[Graham Smith]

I recently ran across some very interesting comments about the 357 Sig cartridge. The consistency and accuracy was reported as being extremely high, which would seem to make it a good choice for target shooting. It occurred to me that I could get a conversion barrel for my Glock 35 if I wanted to experiment, but it also occurred to me that reloading could be a pain.

Having never tried to load any kind of bottleneck cartridge, let alone a bottleneck pistol cartridge, I have to wonder what the difference is between straight cartridges like 9mm and .40 S&W are. Anyone have experience with loading 357 Sig on a progressive press?

[JFlowers]

I had no trouble loading 357SIG on my 550. In fact, I could start with 40S&W brass and end up with 357SIG with no problems. The only issue I ever ran into was setback, where the bullet would get pushed into the case. Running a full powder charge (I had a 357SIG Open Gun) stopped this issue.

[Flexmoney]

Moved out of the beginners section...

-Admin

[L9X25]

I had no trouble loading 357SIG on my 550. In fact, I could start with 40S&W brass and end up with 357SIG with no problems. The only issue I ever ran into was setback, where the bullet would get pushed into the case. Running a full powder charge (I had a 357SIG Open Gun) stopped this issue.

What he said.

The main difference between reloading for a bottleneck cartridge and a straight-wall is that you also have to adjust the depth of the sizer die to place the bottleneck at the proper location, for headspacing purposes. You are also more restriced on your projectile selection since you want to make sure that the case is holding the projectile from an area that is at full projectile diameter. Many FMJ projectiles, and some HP projectiles, reduce the diameter of the projectile very quickly from the base and this can cause the projectile to press into the case on feeding. For an Open gun, you simply choose a powder that fills the case and this reduces or eliminates that tendancy, but that might not be optimal for an uncompensated gun.

[Graham Smith]

I had no trouble loading 357SIG on my 550. In fact, I could start with 40S&W brass and end up with 357SIG with no problems. The only issue I ever ran into was setback, where the bullet would get pushed into the case. Running a full powder charge (I had a 357SIG Open Gun) stopped this issue.

So, you could actually take 40S&W brass and resize it down to 357Sig?

Your second point is something I also saw that concerned me. It seems that choice of bullet is much more critical than with 9mm or 40S&W. Any suggestion on brand, type and size? I was wondering if I could use the MG 121 IFP's I already have for 9mm.

As to which dies, the Dillion dies are very expensive compared to the Lee, or is this a case where you buy individual dies vs a set?

Lastly, do you crimp a 357Sig using a taper or roll die?

[olp73]

Can you actually neck down 40sw brass to make 375sig? I though the sig case was longer?

[JFlowers]

A 357SIG case is actually longer than a 40S&W necked down. But the difference is minimal. The major problem with necked down 40s is that you have less neck and bullet setback can happen more often. As I said, I was running an open gun with a full case of powder so it was never an issue.

I was using Dillon dies. When I bought the 357SIG open gun second hand, the dies came with it. I never lubed cases or anything, just fed them into the press and out the other end. The Dillon set was a standard three die set with a seating die and a crimping die.

As for bullets, I used a 115gr Montana Gold JHP. The flat sided MGs seem to crimp better than the slope sided 124gr Zero JHPs. I also used a batch of 13x grain truncated cones I got somewhere with good results.

Like any new round, it just takes a lot of tweaking to get the press setup correctly.... then reloading the 357SIG was easy.

[Graham Smith]

Interesting. I'm shooting Production right now and will stick with that a while longer, but once I start shooting Limited, I'm going to be looking at various options. After all, what's the sense of shooting a division that allows you to experiment around if you don't experiment around?

Just for giggles, I might get a LWD barrel and some Atlanta Arms ammo next year and experiment with that before trying to load my own.

[JFlowers]

Graham,

Just remember in LIMITED with a 357SIG, you will be shooting Minor, regardless of the fact that you can make Major easily. Not saying you should not experiment and have fun, just be aware of the penalty before you start.

[olp73]

A 357SIG case is actually longer than a 40S&W necked down. But the difference is minimal. The major problem with necked down 40s is that you have less neck and bullet setback can happen more often. As I said, I was running an open gun with a full case of powder so it was never an issue.

I was using Dillon dies. When I bought the 357SIG open gun second hand, the dies came with it. I never lubed cases or anything, just fed them into the press and out the other end. The Dillon set was a standard three die set with a seating die and a crimping die.

As for bullets, I used a 115gr Montana Gold JHP. The flat sided MGs seem to crimp better than the slope sided 124gr Zero JHPs. I also used a batch of 13x grain truncated cones I got somewhere with good results.

Like any new round, it just takes a lot of tweaking to get the press setup correctly.... then reloading the 357SIG was easy.

I have always wanted a 357sig but the prospect halted on the brass. Expensive and difficult to find, at least here. If I can neck down 40 brass then it is another story.

One more question: wouldn’t your “wildcat” sig headspace on the shoulder and not the case mouth, as intended. Are there issues here? Doesn’t accuracy suffer?

[mscott]

I have tried 357sig brass and .40 necked down at the bench and couldn't tell an accuracy difference. My plan was to shoot sig brass for matches and .40 for practice, but I don't think it matters and I just throw them all in the same bucket. When you set up your dies to neck down .40 brass have your barrel handy and adjust your dies so the case just fits your chamber. One shot helps a lot and makes the press run smoother. Start out with a batch of 20 or so and take them to the range to make sure it's all good.

[High Lord Gomer]

Wow! I didn't know it was possible to resize .40 cases to .357 Sig. I liked the .357 Sig rounds that I have shot but never considered it because of the cost/scarcity of cases. Now, hmmm....

[BlackSabbath]

I thought about trying to reload 357 Sig, but never got around to it. I have about 2,500 pieces of onced fired brass. What's it worth? PM me if this is too much of a thread drift.

[Graham Smith]

Just remember in LIMITED with a 357SIG, you will be shooting Minor...

I don't think I had ever noticed that there was a minimum caliber for Major. I thought it was strictly .38 cal or greater plus PF.

Pretty much answers my question of why no one I know was shooting 357 Sig in Limited.

[Cardinal]

357 SIG is now legal in IPSC Standard as a major caliber.

Perhaps USPSA will adopt it as well. But then again that was mainly for countries were 9mm is the biggest caliber allowed.

[Bill Brick]

I recently ran across some very interesting comments about the 357 Sig cartridge. The consistency and accuracy was reported as being extremely high, which would seem to make it a good choice for target shooting. It occurred to me that I could get a conversion barrel for my Glock 35 if I wanted to experiment, but it also occurred to me that reloading could be a pain.

Having never tried to load any kind of bottleneck cartridge, let alone a bottleneck pistol cartridge, I have to wonder what the difference is between straight cartridges like 9mm and .40 S&W are. Anyone have experience with loading 357 Sig on a progressive press?

[Bill Brick]

(Cont'd) from a Glock 35 with 5.3'" KKM barrel 13.1 grains AA#9 drives 124 grain Rainier FP at >1350fps and better accuracy than the same gun with a KKM 40 S&W match barrel. The shape of the bullet does matter because a round nose (RN) will not engage the short neck of the 357 case. Carbide dies are a little more expense but do not absolutely require lubing the cases, and seem to tolerate nickel-plated cases well.

Locally, USPSA accepts 357 for open only in OPEN class at 1335 fps. Accuracy seems to drop off at minor velocities under 1250 fps. Aside benefit is the bottle-necked nickel cases really stand out on the ground, making brass retrieval much easier.

Reloading data is scattered, Accurate Arms and Rainier Ballistics used to list 13.0 to 14.6 of AA#9 for the lead-like TMJ bullets, which is much higher than the 11.7-13.0 of AA#9 listed for 125 grain JHP. 13.0. I stick to 13.0-13.1 and still make Major/open easily out of the 5.3" G35 barrel. (I would not use AA#9 for self defense due to the bright nozzle flash, which is impressive even on a cloudy day.)

[sperman]

Not to thread drift too much, but I've always wondered why anyone would bother with this caliber. I understand it has it's advantages in self defense applications, but for a competition gun it just seems like added headaches without any benefits.

[shooterready]

357 sig headspaces off the mouth of the case, not the shoulder.

[Tom S.]

357 sig headspaces off the mouth of the case, not the shoulder.

Exactly! Consequently, using .40 cases may result in misfires, since the case will be slightly shorter.

[shooterready]

I purchased a G32 barrel to shoot in my G23. I don't shoot it much, but I really like this round. When loaded with HS6, you get some screaming loads. Snappy at that. I recommend 124 bullets or larger. The 115's taper to quickly to get a good crimp.

Fortunately for me, I have a full 5 gallon pail full of clean, once fired sig cases. Half of them are nickel. Enough for me for a long time. Nobody around me loads for it so I'm constantly receiving brass from fellow brass hogs.

You'll find that the neck will crack after about 3-4 loadings of the case. This is due to the high pressure and short bearing surface to the projectile.

Nothing like stuffing a 9mm bullet in a 40 hole to boost reliability.

[High Lord Gomer]

357 sig headspaces off the mouth of the case, not the shoulder.

Is that true of all barrels?

I picked up a .357 Sig barrel for my M&P and since I have a ton of 40 brass, decided to try that. When I resize 40 S&W brass and .357 Sig brass, the shoulders are at identical heights, the mouth is obviously higher on the Sig brass, yet both stop at the same point when chamber checking.

I was a little disappointed that HS6 did not fill up the case enough to appear to provide any resistance to setback, though all 10 rounds I tested fired fine. I also cycled them through the gun several times and measured them afterwards with no change in OAL. FWIW, I used 115 grain Hornady XTP JHPs over 9.0 grains of HS6 (range from Hodgdon's site is 8.7-9.4). I went a little longer than the 1.135 OAL published and loaded mine at 1.140. That allowed me to have a slight, but obvious, bit of the straight side of the bullet still extended above the case mouth. I did crimp more than the WWB personal defense loads I also tested (I pulled one to see how much of an effect their crimp had on the bullet...not much at all). I tried loading some Montana Gold 115 RN CMJs but if I loaded them short enough to fit in the mags, the case mouth was above where the bullet started tapering in and I didn't get a decent crimp.

As a test, I shot 10 WWB .40 Personal Defense rounds, 15 WWB .357 Sig Personal Defense Rounds, and the 10 .357 Sig I reloaded. At 10 yeards I had no noticeable difference in POI among the three loads (but I didn't try shooting them from a rest). I was very suprised and disappointed that 2 of the 15 WWB .357 Sig rounds obviously tumbled. One of them left a perfect profile hole when it went through the paper. My chrono doesn't work at that indoor range, so I'll post back when I get some numbers for those loads.

Edited December 24, 2009 by High Lord Gomer

[Foxbat]

The round is not hard to reload, but a couple of points. One - only bullets with sufficient cylindrical section should be used, which are not too hard to find. You can use Montana Gold, or the Rainier 9mm truncated cone bullets - both give great results.

Second point - using the Lee Factory Crimp die improves the quality and consistency great deal, so it is highly recommended. Both carbide and regular dies can be used, with about equal initial results, but some non-carbide dies will soon develop scratches, so in the long run Dillon carbide dies proved to be a good buy, even at their quite high price.

Outside of the duty/defense role, I see this round largely as just fun shooting. Works great in compensated Glock guns. The amount of flames it shoots up is tremendous with many powders.

[Harmon]

the reloader can set the headspace off of the shoulder. headspace the first time is probably on the shoulder too. pull the bullet on a new case and completely cut off the neck. insert the shortend case into your gun. close the slide, pull the trigger, it WILL detonate the primer.

here is a test of the headspace mystery....article on sig headspace

Edited December 25, 2009 by Harmon

[High Lord Gomer]

Thank you...great advice (and article). I dis go with dDillon carbide and am chamber checking off the shoulder.