Loading 357 Sig

I’ve been loading 38/45 Clerke (a 45 ACP case necked to 38 caliber) since the mid-1980’s and 357 SIG since about 2005. Except for the extra step dealing with the neck and using bullets designed for the 357 SIG, it is not much more difficult than loading a straight walled pistol case.

Neck tension is important. Get that right. Usually reducing the diameter of the expander ball will be enough. But, if the sizing die does not reduce the neck enough, the die does need to be replaced.

I minimize case mouth flare to an absolute minimum then lightly taper crimp to remove the flare.
 
I used 7.9 grains No5 with CCI primers. 124 grain jacketed hp bullets. Three out of ten fired. I‘ll review everything including the successful empties. My new 9mm slide is due in Tuesday.
 
dh1633pm said:
Projectiles in good supply. Mostly 125’s and 147’s there about…
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Are the above 125s & 147s 357 Sig-designated projectiles, because many (most?) 9mm .355 bullet ogives are not 357 Sig-friendly.

@vaalpens mentioned RMR Match Winner bullets & since the demise of Montana Gold, those versatile 115 & 124gr MWs have become not only my go-to 357 Sig, but also 9mm & 38 Super range bullets of choice.

Another lesser known, but first-rate 357 Sig bullet is available from Precision Delta - in my experience, they are on par with the gold-standard, Zero & Montana Gold offerings.

Though perpetually out of stock, because in PD’s words, demand for 357 Sig has gone down over the past couple years, they will become available again in the near future. If interested, sign up for the Back In Stock notification:
www.precisiondelta.com

.357 Sig 125gr FMJ

Precision Delta 130 grain FMJ bullets make a great choice for any 38 Special or 357 Magnum hand loader. Made from a swaged lead core and copper jacket, our FMJ bullets are renowned for their consistency and accuracy.
www.precisiondelta.com www.precisiondelta.com
 
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Thanks @riverats and no they probably are not. Yes I did read @vaalpens comments. Took them to heart and marked them down. The ones I did load, functioned properly when they functioned (30%). I will be checking the ammo this week to see where I went ID Ten Tee on them. Taking my time but also absorbing the input given here. I'll figure it out.
 
A 357S barrel is on my short list for my G22.3.

I wonder why Glock stopped selling barrels? I know aftermarket is an option. Just curious why you can’t get an “OEM” barrel.
 
mdi said:
I have only been reloading 357 Sig for a few months. I have found that I can size with a 40 S&W carbide sizing die and forego lube, case body same size. Then size neck with my Lee die. Plunk test 90% of my loaded rounds and check neck tension, so far have kept loads on the lower side. Longshot and CFE Pistol data right out of my manuals (357 Sig barrel in my Glock 22 gen 5 loud and smart recoil).
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What aftermarket barrel did you go with?
 
dh1633pm said:
The ones I did load, functioned properly when they functioned (30%). I will be checking the ammo this week to see where I went ID Ten Tee on them. Taking my time but also absorbing the input given here. I'll figure it out.
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Two things that were early sources of (much!) frustration for me were correct shoulder placement & secondly, one you won't hear mentioned often, not enough flaring at the case mouth ... both issues were exacerbated due to my ignorance (☺️) & secondly, the less-roomy chamber on the Bar-Sto barrel I ordered for a P226 (which, ten 357 Sig pistols later, is still my favorite). While one must certainly mind neck tension, etc., because of stingy flaring, I was ever so slightly bulging the necks, which led to more FT fully chamber(s) than I care to mention. My shoulder issues were remedied by the acquisition of an EGW case gauge/ammo checker & shortly thereafter, the brilliant, but twice as expensive Sheridan Engineering slotted ammunition gauge.

FWIW & as mentioned elsewhere, I go the lubeless 40 S&W carbide and then, 357 Sig sizing die route; then chamfer the case mouth; flare & lastly, apply a light crimp to remove flaring (Lee FC collet die). My favorite powders are AA#9 & Hodgdon's (sadly!) now-discontinued Hi-Skor 800-X ... AA#9 because of excellent metering & compressed charges, which preclude bullet setback on near-max/max loads and 800-X because, though it meters like Dorito chips, it's capable of amazing velocities at lower pressures.

Case gauge links:
Sheridan: https://sheridanengineering.com/product/357-sig-ammunition-gauge/
EGW: https://egwguns.com/case-gauge-ammo-checker-357-sig-7-hole
 
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dh1633pm said:
Inventory. Not pictured is green dot and Lil Gun. No, haven’t looked at the reloading books yet. Projectiles in good supply. Mostly 125’s and 147’s there about.
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I mostly use different powders but Unique, AA5 and AA9 should be good. I have never used AA9, but a lot of reloaders love it in 357sig.

I don't load any volume/bulk using Unique, but one of my most accurate loads are using Unique. The load is on the lower end, so I don't mind sharing it here:
357sig, P229, 3.9", Case: Speer, COL: 1.140"
RMR, 124gr, TCFPMW, Unique, 7.1gr, CCI500
Velocities: 1254, 1265, 1247, 1247, 1261
Average: 1254, ES: 18, SD: 8.1, Force: 433, PF: 155
Grouping @ 15yd: 0.478"
Test Date: 10/08/2017


I have just started testing 147gr loads using AA5, and it seems very accurate. For some reason I did not capture any velocities for my AA5 load. This load is also on the low end so I don't mind sharing it:
357sig, P229, 3.9", Case: Speer, COL: 1.140"
RMR, 147gr, TCFPMW, AA5, 7.2gr, CCI500
Grouping @ 15yd: 0.59"
Test Date: 09/14/2023
 
I figured my shoulders were off. Or primers not set right. Both easy to check. Thanks @riverats and @vaalpens for taking the time to respond, i am certainly listening. @Misplacedtexan says he likes No 9. Gotta lot of Unique, No 5, and No 9. Time isn’t my friend this time of year. Preparing for winter. Mowers, tractor, 4-wheeler all need winter attention. Hunting starts this week. Can’t say enough how I appreciate the input. What is in one’s brain is valuable.
 
I load its big brother 9x25 Dillon and the problems I've had have largely been addressed in this thread already. My biggest one is shoulder bump, as some die and shell holder combinations can set the shoulder back far enough that your firing pin won't make reliable contact with the primer. A case gauge can be of immense help when setting up a die for a bottleneck cartridge. The issue of an undersized neck is real, and you can easily collapse the shoulder when trying to seat a bullet that has a very square base. Try the plunk test and make sure your completed round will spin in the chamber without engaging the rifling. If you have factory ammo, compare how deeply it sits below flush compared to your reloads.
 
IIRC Speer brass has smaller flash holes. My first sizing/depriming attempt was with Speer nickel plated cases and I bent one pin and pushed back my Lee pin a few times...
 
.357 Sig with 125gr bullets are close to a .357 magnum with 125gr bullets. Since Blue Dot works well with the .357 magnum, has anyone tried this with .357 Sig loads?
 
.357 Sig is by far my favorite full sized pistol defensive cartridge in a P226 (custom built by GrayGuns) because it is a .357 Magnum semi auto. I use a 650 Dillion with Dillon carbide dies and a Lee factory crimp die. 125 grain hollow points are the way to go for sure . M favorite 9x19 loads are 147 grain, but the .357 Sig works much better and more powerful with 125 JHP and my favorite load is a Sierra 125 grain Sports master JHP as the profile (long parallel shank) is ideal for the .357 SIG , a very important quirk of the cartridge .
\https://www.sierrabullets.com/product/9mm-125-gr-jhp-sports-master/
1731476159463.png I use almost a case full of Accurate #9 load I worked up, which I have several pounds left of, Accurate #9 thank goodness, I get 1400+- FPS from a 4.6" barrel with this bullet load, which has perfect cycling, it feels like a factory 165 .40 S&W in recoil to me, snappy but not a 10mm, so you can get fast split times. It shoots super flat well beyond 100 yards and is just like a good .357 Mag Revolver , with 15+ shots and faster reloads. I too have a .40 S&W barrel and a 9mm threaded barrel for the P226 and they all run flawlessly. :)
 
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AA#9 is a good 357 SIG powder.... AA#5 is OK, Longshot is great, 800x is great(but metering sucks), Enforcer is good for heavier bullets, HS6(Win 540) is good...there are several other powders that work... but if you want 357 SIG performance, the slower powders above work best....if you gonna shoot 9mm loads ...get a 9mm and be done
 
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