IV. Comparative Firearm and Ammunition Information

G. Calibre Issues

15. .357 Sig Cautionary FAQ

I'm a 357 Sig fan and I've been shooting this caliber 
since 1995. I've shot factory 357 Sig ammo and I reload 
this caliber on a regular basis. But I'm posting this 
warning to ALL 357 Sig shooters out there. There is an 
issue with the 357 Sig in regard to both factory and 
reloaded ammo. This is NOT a major issue as long as you 
are aware of it, and take the necessary precautions. Not 
understanding it could result in problems.

The Issue:

The 357 Sig bullet 'can' creep or slip into the case, 
even with brand new factory ammo, based on my experience. 
While this condition can occur with most all calibers, 
the 357 Sig only has approximately 1/8" of neck to hold 
the bullet, although that is sufficient if the round is 
loaded correctly. Another issue which is discussed in 
item 13 below, is that the 357 Sig shoulder may not always 
be positioned correctly, which can cause strange light 
primer strikes and ignition problems.
 
There is a simple work-around for agencies and those who 
carry the 357 Sig on a regular basis. This is especially 
critical for those that constantly unload and reload the 
same duty ammo into their gun over and over again, 
possibly for months.

Obviously, if you carry your pistol on duty or in 
concealed carry, you must occasionally practice with your 
pistol to make sure everything is working well. In order 
to do that, you take out the expensive 357 Sig ammo and 
replace it with practice ammo. After the practice session 
and after cleaning the pistol, the expensive 357 Sig Duty 
Ammo is loaded back in the gun. The agencies that I'm 
familiar with don't generally have the luxury of shooting 
out the expensive duty ammo and getting a fresh supply 
during each practice session!

Oh, you don't believe there is an issue? Try this 
experiment. Measure the Over-All-Length (OAL) of your 
factory and/or reloaded 357 Sig cartridge, and then put 
that round into your magazine and rack the round into the 
pistol chamber, using the full force of the slide spring. 
Then, carefully extract the cartridge and measure the OAL 
again. Do this procedure 5 - 10 times in a row. I rest my 
case. For what it's worth, the bullet  holds in place
best with new brass.

Various ammo companies such as Speer have indeed replaced 
357 Sig ammo on request. Hopefully, in time this concern 
will become a moot point for this new round, although 
it's a team effort; the Ammo Company has to manufacture 
good ammo and the consumer has to follow some common 
sense solutions as described below. But for now, it's a 
malfunction waiting to happen. Follow the simple 
solutions below so you're not caught off guard. 

Solution for those who carry factory 357 Sig ammo:

First, make sure your duty ammo functions well in your
gun by firing many rounds through it. Don't assume.

Next, rotate the order of your duty ammo each time you 
reload your factory ammo into a magazine. The cartridge 
that 'was' in the chamber most recently, becomes the 
bottom round in the magazine next time you reload your 
gun. Also, before reloading the factory ammo into your 
magazine(s), use calipers if you are not sure about 
eyeballing the OAL (cartridge over-all-length). If the 
original length is say 1.135", then when it gets down to 
say 1.130", replace it. 

I can't necessarily recommend this to others, but I go 
ahead and shoot the 'slightly' shortened cartridge, as 
long as it doesn't get too short! This call is best made 
by you and/or your range officer, and should be based on 
the type of powder used, etc. You 'should' request a 
minimum safe OAL from the ammo manufacturer; if nothing 
else, this would alert the ammo company that you are 
concerned and are indeed aware of a quality safety issue.

Ernest, an Ammo Manufacturing Engineer, stated the 
following:

"There are a TON of folks out there who constantly load 
and unload the top round in their magazine, and then 
complain that the overall length is changing. In fact, 
battery of the case neck can weaken it so much, that the 
shrinking tendency will rebound, and all of a sudden, the 
bullet is gone! Where? Down the bore! The darn things pop 
out of the case upon chambering and fly down the
bore to create an obstruction for the next round. (This 
happens when there is excessive free-bore between the 
chamber mouth and beginning of the rifling) Then, the 
shooter complains I sent him a cartridge with no bullet. 
Never mind the fact the powder arrived in a case, without 
a bullet, and found its way into the chamber without 
spilling somewhere along the way."

Just because it's factory ammo, regardless of caliber, do 
not blindly believe it is therefore OK and will always be 
OK. Go ahead and monitor the OAL and do the thumb 
pressure test as described in the next section. Take 
these few simple precautions seriously. 

Solution for those who reload 357 Sig ammo:

This is what works for me. Use your own discretion to see 
if you wish to follow any of my suggestions. I'm not responsible 
for your actions 

Reloaders should have less of an issue since they 
normally just load the ammo once into their gun and shoot 
it. They just have to follow the necessary reloading 
precautions to make sure their reloads are adequate.

1. Use good brass and check it each time before reuse. 

2. Count your brass usage, so everything in a given group 
has the same age, wear, brand, etc.

3. Check the trim length, especially if you are loading 
full power rounds. If you use groups of brass as 
mentioned in item 2, you may be able to just spot check 
some brass to get a good idea if the trim length is 
staying within specs. If you don't use groups of brass, 
then you should check every brass. I've never had to trim 
my Starline brass.

4. Lightly spray lube the cases before resizing. There is
an engineering necessity why bottlenecked cases need to be 
lubed. Even if you believe you're successfully getting 
away without lubing the small 357 Sig case, you are 
asking for trouble. Refer to a good reloading manual for 
the details. 

I have never directly lubed the inside of the case neck, in 
conjunction with using a Dillon carbide resizer, and have had 
no ill effects to date. Although, an indirect lube does occur 
inside the neck, from my fingers constantly holding the top of 
the neck and manipulating the bullet to be seated.

5. Do a full case resizing to form the brass as close as 
possible to its original shape. I highly recommend the Dillon
carbide resizer, which does an excellent job. It's expensive
and costs around $75, but well worth it. The carbide resizer
still requires lubed cases, but does not produce as much 
friction as all-steel resizers, and makes operating the
press a little bit easier as a result.

6. Do not expand the case opening so you can visibly see the 
belling effect! Instead, just lightly expand the mouth opening 
so the bullet will just barely squeeze into the case. This 
will cause the bullet to hold much more firmly in place --- 
very important! A bullet with a slightly beveled base, or even 
a tapered base, is best (examples: Rainier 124 gr. flat point 
and the Hornady 147 gr. XTP). 

For a rough example using Rainier plated 124 grain flat 
point bullets: I do a full resize and the mouth measures 
aprox. .374. In the belling stage, I expand the neck to 
roughly .378 - it does not look belled at all. I then 
seat the bullet which then measures aprox. .3795. I then 
crimp which brings the measurement to aprox. .379. 

If the bullet does not have a beveled base, you 
`might' have to expand the neck just a tiny hair more --- 
but keep it as tight as possible so the bullet just 
barely fits --- I cannot over-stress this fact. Another 
possibility is to lightly chamfer the case mouth so the 
bullet can be seated without crushing the case (I haven't 
personally used chamfering for my reloads). 

7. Use a 9mm bullet that has a .355" bearing surface at 
the point where you will be crimping, otherwise, the 
bullet will have a tendency to slip, and/or you will be 
forced to crimp far tighter than the recommended SAAMI 
specs. 

Many 9mm bullets are unsatisfactory because they have a 
long tapered bearing surface. Some are deceiving since 
they measure around .352 at the crimp point, so be 
careful. 

Speer actually makes 357 Sig labeled Gold Dot 
and TMJ 125/147 grain bullets, These heavier bullets are 
quieter than the faster 125 grain loads, and are still 
more potent than when loaded in 9mm Luger or 38 
Super --- not bad for being shot out of the same size 
pistol as a 9mm Luger.

Speer, Hornady, and Rainier bullets can be found in 
various gun supply stores and mail order stores like 
Blue Press, Midway, etc. I just found another excellent
124 grain flat point bullet that is full metal jacketed 
(ideal for maximum velocities) and available for aprox. 
$55/1000 from D & J Bullets (www.djbullets.com). 

8. The SAAMI taper specification is .381. I taper crimp 
to around .379, which is a firm taper. I have taper crimped
as tight as .378 to .379, with no ill effect. It might 
even cause a slight taper ring around a soft bullet, such 
as the Rainier 124 grain flat points. Too much crimp can 
cause accuracy problems, deformation of the bullet, 
seating problems in the chamber, and can actually cause 
the bullet to loosen up.

If you are taper crimping down to .376 or so, then the 
bullet you're using does not have a .355 bearing surface 
at the crimp point, or you are deforming the bullet.

9. Wipe the lube off by using a vibrator tumbler for 10 
minutes, or, use whatever technique you feel comfortable 
with.

10. I prefer to use the higher end of the maximum Over-
All-Length for the 357 Sig cartridge. Maximum is 1.140. 
So I generally keep my rounds between 1.135 and 1.140. 
This is a good safety factor for lessening an over-
pressure occurrence, just in case the unexpected bullet 
slippage should occur. 

11. I prefer to use a powder that fills the case like 
Blue Dot or AA#9. These powders can actually help hold 
the bullet in place and still maintain acceptable 
pressures, based on studies done by AA and Mermelstein. 
Another excellent propellant for the 357 Sig and .40S&W 
is Power Pistol, which is a medium-slow burning 
powder. The 50th edition Sierra Reloading Manual and the 
13th edition of the Speer Reloading manual give examples 
of several powders used for the 357 Sig. The newest 
editions of Reloading Manuals that will be coming out in 
the near future will no doubt be supporting this new round 
as well.

12. Spot check some cartridges by performing the thumb 
pressure test. Once again, it's best to be using a group 
of brass with the same brand, age, etc so characteristics 
will be similar. Put the bullet end of the cartridge on a 
hard surface, and gently apply fairly strong thumb 
pressure on the primer end. Measure the OAL before and 
after this test to make sure the bullet is holding. 

You can do the thumb pressure test on a weighing scale; 
it should be able to at least handle 45 pounds of 
pressure. If you keep performing this test over and over 
again, you will eventually be able to push the bullet all 
the way into the case.

The cartridge should be able to handle the thumb pressure 
test in order to simulate having the cartridge forcefully 
fed into the chamber. In fact, instead of the thumb 
pressure test, you can use a magazine to simply load a 
round into the chamber using the full force of the slide 
spring.  Then carefully extract it and measure the OAL to 
make sure it is passing the test.

13. And Finally, Headspace (To be on the case mouth, or, To 
be on the shoulder, That is the question):

The very first 357 Sig article I read was in the second half of 
1995, written by Ed Sanow. He got his facts from Federal and Sig 
Saur, with a touch of his own thoughts as well. At that time, 
he wrote that the 357 Sig headspaces on the case mouth, making it 
easier to measure the OAL (over-all-length).

Well, it's getting close to 2000, and the 357 Sig has been
maturing. Now I've been told from a couple reliable sources,
that the 357 Sig headspaces on the case mouth and the shoulder.
More, recently, I read that the shoulder has precedence in
determining headspace. I have not officially seen something in 
writing from Sig Arms or an ammo company to absolutely clarify 
this point. 

Based on all of this interesting headspace info, I currently
believe that if you are experiencing light primer strikes and
inconsistent ignition, then very likely, cases have been
sized with an improperly positioned shoulder. All the other
measurements like trim length, OAL, etc, are important too of
course.

I base this information on my own personal experience, and the
archive article listed below, as well as observing weak primer
strikes from a fellow shooter at a recent IPSC match.

The base of the shoulder is 0.6490", measured from the 
bottom of the case. The top of the shoulder measures 0.7150". 
I was taught that a bottlenecked cartridge headspaces midway on 
the shoulder. In the case of the 357 Sig, that means it headspaces
at right around 0.6820. With a set of calipers, it is easy
enough to measure from the bottom of the case to the mid
shoulder position to see if you're in the ball park.

Interestingly enough, with my Dillon 550, Dillon dies and 
a Lee crimper, I have never had a problem loading the 
357 Sig. My agony was to initially find 9mm bullets that were 
compatible with this new cartridge.

I just reloaded the same 357 Sig brass for the tenth time, and 
all measurements are still fine. The shoulder is positioned fine,
and the bullet is still holding snug. Until recently, I never even 
measured the shoulder headspacing as a standard check. But I'm 
very glad to be aware of it now.

I have been lucky with my particular 357 Sig setup. There are
many different dies, presses, guns, people, etc. So some people
have had problems and others haven't. Hopefully, as we all
learn more about the 357 Sig, and "CORRECT" reloading data
is published, it will be easy for even a "New Reloader" to come 
up to speed fast. After all, the 357 Sig ain't a century old 
like the venerable 9mm and .45 --- nothing like being a pioneer!

Addendum:

I'm not trying to be a know-it-all by giving out this 
information. If anybody has more information, additions, and/or 
corrections, please let me know. I just want everyone to 
be safe while they're shooting the excellent 357 Sig 
round. And I strongly believe that anyone who uses the 
357 Sig should be aware of this faq.

Here's some sites that have some good 357 Sig info:

stenhammar.net/guns/sig/357sig.html
www.realguns.com/archives/001.htm (357 Sig headspace article)
odaiko.ss.uci.edu/sig/sig.html
www.greent.com

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