Questions about reloading the 357 Sig cartridge

lrrifleman · Jan 12, 2021

From what I am gleaning from most reloading data sites, is that almost any 100-124/5 gr 9mm JHP bullet can be used to reload the 357 Sig. Is this a reasonable observation?

For those that reload 357 Sig, how much of the overall length of the bullet needs to be dedicated to the bearing surface as opposed to the bullet nose?

As always, thanks in advance for your help!

STORMINORMAN · Jan 12, 2021

For the most part my experience has been that in bullet weights 115gr & above flat pointed (i.e., Berrys HBFN-TP for practice/range use) or hollow pointed bullets (i.e., XTP, Gold Dot for HD/PD) work best for 357 SIG because the recommended OAL is typically 1.135" (1.140" for 147gr).

Round nosed or conical bullets don't always allow enough of the bullet past the ogive (some refer to it as the caliber diameter) to secure within the case. Pushback can also be a factor with 357 SIG velocities: I use the LEE FCD which is a collet-style crimp die (often used with bottleneck rifle cartridges) with much confidence.

If you take a look at the profiles of bullets specifically designated as being for 357 SIG I think you will notice their similarities.

There are other posts on this sub-forum about dies you may find instructional as well.

Cheers!

cowboy4evr · Jan 12, 2021

I will offer up a suggestion , what I found has helped me . I found a case gauge very helpful . Occasionally I had a case that the sizing die couldn't totally resize . A slight bulge was still there near the base . The last time I resized / deprimed 50 cases I had 5 that would not fit into the case gauge . I bought the LEE push through sizer . It fixed my problem . I also found that Berry's Bullets sized .356 , heavy plated , for 357 sig the most accurate vs .355 . For powders I liked Accurate #9 and Alliant Blue Dot . That has been my experience in my Sig P320 converted to 357 sig . Regards Paul

STORMINORMAN · Jan 12, 2021

That's the one: their No. 00335. IMHO the Wilson Case Gage is a must for reloading 357 SIG as well. I routinely check the cases after sizing, before new primers, expansion, powder, seating & the crimp. And after all's done, as well. I'll plunk test a couple in my 357 SIG barrels before I get into any real "production". There are variations in chambers, and with a bottleneck cartridge this can make a difference.

Belt & suspenders...maybe? So far all my 357 SIG reloads have fired perfectly.

A side note: resizing the cases with a 40 S&W carbide die 1st, then with the 357 SIG sizing die (most are not carbide) works very well for me. No need to lubricate so far.

Cheers!

lrrifleman · Jan 12, 2021

Thanks for the information. I already have my dies and a Lee FCD, all that is missing are the bullets! I've noticed that it appears as though the ogive of the round nosed bullets tends to put the bearing surface below the case mouth. I have about a thousand Hornady HAP bullets that I'm trying to get a feel for. All that is missing at the moment is the 357 Sig barrel for the 229, so I can't yet experiment with a "plop" test!

STORMINORMAN · Jan 12, 2021

Those HAPs should work just fine. They are, basically, an XTP without the cuts for flutes.

fredj338 · Jan 12, 2021

lrrifleman said:
From what I am gleaning from most reloading data sites, is that almost any 100-124/5 gr 9mm JHP bullet can be used to reload the 357 Sig. Is this a reasonable observation?

For those that reload 357 Sig, how much of the overall length of the bullet needs to be dedicated to the bearing surface as opposed to the bullet nose?

As always, thanks in advance for your help!

Not any 9mm but truncated cone above 115gr. You need enough bearing surface inside the case neck, but that isnt the issue. The issue is getting enough bearing surface inside the case neck & still make oal.
The only carbide dies I am aware of are Dillon. Expensive but worth it to me.

Coastie762 · Jan 13, 2021

The short neck of the .357 Sig requires some care when selecting a bullet for reloading. The common round nose 9mm projectiles can't be used as their ogives don't permit maximum contact with the case neck.

A bullet with a straight shank (the Hornady HAP or XTP is an excellent choice) is necessary for the case to get a proper grip on the projectile. I made up the attached photo a few years ago to show the difference.

fredj338 · Jan 13, 2021

Coastie762 said:
The short neck of the .357 Sig requires some care when selecting a bullet for reloading. The common round nose 9mm projectiles can't be used as their ogives don't permit maximum contact with the case neck.

A bullet with a straight shank (the Hornady HAP or XTP is an excellent choice) is necessary for the case to get a proper grip on the projectile. I made up the attached photo a few years ago to show the difference.

You can load a RN if the bullets are light enough, below 115gr.

STORMINORMAN · Jan 14, 2021

I would like to concur regarding the use of lighter bullets: in my experience many 90 and 95gr JHPs & SJHPs load up with no problems re: OAL or sufficient bullet contact with the case neck (fredj338 refers to this as the "bearing surface") to insure they can be properly seated and crimped.

Even with START loads these projectiles are moving at relatively speedy velocities (as in 1,400 fps) and the recoil is minimal. Fun, fun at the range.

Cheers!

Racer X · Jan 14, 2021

I'm now scratching my head. So, lighter bullets will have MORE "bearing surface"?

Just getting into reloading, and .357 SIG is one of the calibers I will be doing.

STORMINORMAN · Jan 14, 2021

Not exactly, but...

No, not because they are light, but because they are usually short enough that there is sufficient length past the ogive that extends into the neck of the case to be firmly seated and crimped.

colt_saa · Jan 14, 2021

Racer X said:
I'm now scratching my head. So, lighter bullets will have MORE "bearing surface"?

Just getting into reloading, and .357 SIG is one of the calibers I will be doing.

No not more bearing surface

357SIG has a very short neck. many heavier (longer) projectiles have their bearing surface ending up too far inside the case, thus it is not aligned in the neck for good tension.

I started shooting 357SIG in 1993. I was working in Dallas County and I had access to some of the Texas DPS guys that were involved with the evaluation of the cartridge. That is where I shot my first SIG P229

I used to go through LOTS of 357SIG (6000+ annually). I have loaded tens of thousands of rounds over the years. These days it loads just as smoothly as 45 ACP or 357 Magnum

lrrifleman,
As STORMINORMAN points out that Lee FCD imparts a collet crimp that virtually eliminates neck tension issues as long as the profile of your projectile puts some of the bearing surface at the case mouth. Before discussing with LEE about the possibilities of a collet crimp die for this cartridge, I reduced the diameter of the expander plug by a little over .001" to try and increase neck tension with some of the iffy projectiles

The Montana Gold 357SIG projectiles are great as are the Hornady XTPs and HAPs. It is that truncated cone shape that works so good with this cartridge. I am not sure if I ever loaded plated in this cartridge due to the velocities.

I have a cute 90 grain JHP that leaves my SIG X5 at 1700 FPS when pushed by a nice charge of Power Pistol. It is Extremely accurate in my SIG P229 Sport

Prior to our current Constitutional Crisis this projectile was very reasonably priced even if I only bought a few thousand at a time

That 90 JHP load moves out even faster from my 8.9" MP5, though I have not chronographed it

I have not loaded anything above 147/150s though I have a buddy that goes over 160 grains with a custom made JHP. I only go heavy for suppressed use. Most of what I load are 124/125s or the 90s

I load on a five stage progressive press and like STORMINORMAN my first die is a carbide 40 S&W sizer. Without that the handle pressure on my press was excessive. Now I do lube the cases with Hornady One Shot. Every few hundred rounds I give a little squire into the 5 gallon bucket of grass and do a quick hand stir

Station 2 is the 357SIG sizing die and priming. I did have a chance to try the Dillon carbide die on the press but it made no appreciable difference in handle force needed over a steel sizer even though it cost 4-5 times as much

Station 3 drops powder and expands the case mouth

Obviously I seat and crimp at stations 4 and 5 respectively

fredj338 · Jan 14, 2021

colt_saa said:
No not more bearing surface

357SIG has a very short neck. many heavier (longer) projectiles have their bearing surface ending up too far inside the case, thus it is not aligned in the neck for good tension.

I started shooting 357SIG in 1993. I was working in Dallas County and I had access to some of the Texas DPS guys that were involved with the evaluation of the cartridge. That is where I shot my first SIG P229

I used to go through LOTS of 357SIG (6000+ annually). I have loaded tens of thousands of rounds over the years. These days it loads just as smoothly as 45 ACP or 357 Magnum

lrrifleman,
As STORMINORMAN points out that Lee FCD imparts a collet crimp that virtually eliminates neck tension issues as long as the profile of your projectile puts some of the bearing surface at the case mouth. Before discussing with LEE about the possibilities of a collet crimp die for this cartridge, I reduced the diameter of the expander plug by a little over .001" to try and increase neck tension with some of the iffy projectiles

The Montana Gold 357SIG projectiles are great as are the Hornady XTPs and HAPs. It is that truncated cone shape that works so good with this cartridge. I am not sure if I ever loaded plated in this cartridge due to the velocities.

I have a cute 90 grain JHP that leaves my SIG X5 at 1700 FPS when pushed by a nice charge of Power Pistol. It is Extremely accurate in my SIG P229 Sport]

Prior to our current Constitutional Crisis this projectile was very reasonably priced even if I only bought a few thousand at a time

That 90 JHP load moves out even faster from my 8.9" MP5, though I have not chronographed it

I have not loaded anything above 147/150s though I have a buddy that goes over 160 grains with a custom made JHP. I only go heavy for suppressed use. Most of what I load are 124/125s or the 90s

I load on a five stage progressive press and like STORMINORMAN my first die is a carbide 40 S&W sizer. Without that the handle pressure on my press was excessive. Now I do lube the cases with Hornady One Shot. Every few hundred rounds I give a little squire into the 5 gallon bucket of grass and do a quick hand stir

Station 2 is the 357SIG sizing die and priming. I did have a chance to try the Dillon carbide die on the press but it made no appreciable difference in handle force needed over a steel sizer even though it cost 4-5 times as much

Station 3 drops powder and expands the case mouth

Obviously I seat and crimp at stations 4 and 5 respectively

The diff with the dillon carbide is I dont need case lube or the extra step of a 40 sizer. I think the cost is worth removing steps.

colt_saa · Jan 14, 2021

fredj338 said:
The diff with the dillon carbide is I dont need case lube or the extra step of a 40 sizer. I think the cost is worth removing steps.

Fred,
On a progressive press, the 40 sizer does not add another step.

Everything happens with a single pull of the handle whether there are 4 dies mounted or 5

I do not NEED to use lube either with my 5 die setup, but when I use One Shot case lube, handle pressure is reduced. So fatigue is reduced and I can load for a longer period of time producing more rounds in a single session.

To me that makes the $15 can of One Shot lube a mandatory item. That one can lasts many tens of thousands of rounds.

I use One Shot on every cartridge that I hand load. Even with carbide dies

Why would you possibly choose to exert MORE effort when you do not have to?

Other than to save that $15 expenditure every year or two

Racer X · Jan 14, 2021

This is fantastic info everyone! One of many reasons I love this place. My Lee press is a 5 station press, the LoadMaster. I can easily set up my .357 Sig die plate with station 1 a carbide .40 sizer.

fredj338 · Jan 14, 2021

colt_saa said:
Fred,
On a progressive press, the 40 sizer does not add another step.

Everything happens with a single pull of the handle whether there are 4 dies mounted or 5

I do not NEED to use lube either with my 5 die setup, but when I use One Shot case lube, handle pressure is reduced. So fatigue is reduced and I can load for a longer period of time producing more rounds in a single session.

To me that makes the $15 can of One Shot lube a mandatory item. That one can lasts many tens of thousands of rounds.

I use One Shot on every cartridge that I hand load. Even with carbide dies

Why would you possibly choose to exert MORE effort when you do not have to?

Other than to save that $15 expenditure every year or two

I supposecit deoends on the press, but adding a 40 to my 550 or 650 woudnt work. I do spray a bit of OS on a few cases but the carbide dies do work well withought.

460harry · Jan 15, 2021

lrrifleman said:
From what I am gleaning from most reloading data sites, is that almost any 100-124/5 gr 9mm JHP bullet can be used to reload the 357 Sig. Is this a reasonable observation?

For those that reload 357 Sig, how much of the overall length of the bullet needs to be dedicated to the bearing surface as opposed to the bullet nose?

As always, thanks in advance for your help!

Yes. I've loaded 9mm speer 124 grain and 9mm armscor 124 grain, both worked well.

As for the second question, I interpret that as how far the bullet needs to be seated. I seat the 9mm 124s just deep enough to feed reliably in my magazine, which of course may vary across brands. I shoot a p320. Keep in mind that the 9mm bullets seat deeper than the 125 grain 357 sig specific .355 bullets, so your pressure is going to be slightly higher for any given load.

460harry · Jan 15, 2021

Coastie762 said:
The short neck of the .357 Sig requires some care when selecting a bullet for reloading. The common round nose 9mm projectiles can't be used as their ogives don't permit maximum contact with the case neck.

A bullet with a straight shank (the Hornady HAP or XTP is an excellent choice) is necessary for the case to get a proper grip on the projectile. I made up the attached photo a few years ago to show the difference.

This is the proper way to go, but round nose 124 grain 9mms can definitely be loaded and shot accurately in 357 Sig. I've put a few thousand downrange with maximum longshot charges and only had some slight bulging here and there after about 4 or 5 reloads of the brass. Never had a problem with bullet setback or unintentional pressure problems. Obviously if you don't feel comfortable doing it, then don't. I'm just always trying to save money when I can.

STORMINORMAN · Jan 15, 2021

I'm really confused! 357 SIG MAX loads of Longshot for 124gr XTPs per Hodgdons data is 9.3 gr @ 1,429 with a 4.00" barrel: pressure is listed as 37,900 PSI.

Their START for 357 Magnum with Longshot and a 125gr XTP is 8.2 gr @ 1,529 and their MAX is 9.7 gr @ 1,647 in a 10.00" barrel: pressure shown as 42,000 CUP.

Nonwithstanding the different way pressure is expressed, doesn't the 357 Magnum case have a significantly greater volume (26.2) than the 357 SIG (19.5)? Especially when using what are basically the same size bullets? There's the lack of a cannelure on the .355, but the profiles are really not that different...

I'm not trying to argue apples vs. oranges here, but shouldn't a case THAT MUCH smaller (as in 25+%) in volume generate significantly higher pressures were the powder loads to be equal... Say, using 9.2 gr which is halfway between the Magnum's START and MAX? Wouldn't the smaller case pressure be higher?

We get routinely concerned with an unintentional increase in pressure when bullets are loaded deeper by relatively minute amounts (typically measured in thousandths, even hundredths of an inch?), nothing that would ever result in a 25% decrease in case volume?

P.S. From what I can determine that MAX Magnum load pressure of 42,000 CPU × 1.516 - 17,902 = 45,770 PSI (approximately?)

Questions about reloading the 357 Sig cartridge

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