Perhaps one of the most difficult rounds to reload is the
.357 Sig, primarily because newcomers have many issues with reloading it. The
two common issues with this round is poor headspacing, causing problems with
chambering and inconsistency, and bullet setback. Both of these problems can be
avoided by taking a fewer precautions in your reloading process. Let’s look at
each individually to see where the problems are with the .357 sig.
The problem with head spacing on the .357 Sig comes from confusion
on the proper way to the location of the headspace, either on the mouth or
shoulder of the cartridge. Most reloading manuals will put the headspace on the
mouth while the C.I.P (the European version of SAAMI) says that is should be
headspaced on the shoulder. In actuality, it depends on the gun. Some chambers
are so long that headspacing on the shoulder is the only way to go.
The foolproof way to go is treat the .357 Sig like a rimless
bottleneck rifle case, and size it so that it head spaces on the shoulder for
your gun. Here's how to do it:
Take a fired case, and measure the
distance from the case head to a point about midway on the shoulder.
Set the sizing die depth so that
the shoulder on the sized case is pushed back 0.003" shorter than the
Do a small lot and fire them to
make sure they feed and shoot OK.
Keep in mind that cartridges
sized this way may not run right in other guns, but they'll work in your gun.
This is an issue on the .357 Sig due to its short neck not giving
enough hold on the bullet. Most of the time, this problem is caused by using
the wrong bullet or belling the case mouth too much. Since the .357 is
essentially a 9mm, the allure is the vast array of bullets available. The
trouble is that most actually won’t work.
When you load some of these bullets into the .357 Sig
case and set the OAL to what is specified in the manual, you can end up loading
a cartridge where the short neck and the short bullet bearing surface don't
entirely line up.
This makes a bad situation worse. This usually
happens when an inexperienced reloader uses the data in a manual for a bullet
that is the same weight, but a different shape than the one in the manual.
two things you can do that will minimize the chances of bullet setback
occurring. One is to use bullets specifically designed for the .357 Sig
(such as those made by Speer). If you can find bullets with a cannelure,
you can roll crimp the cartridge (because you'll be headspacing on the shoulder).
Really light bullets (such as those intended for loading the .380) do
not work very well in the .357 Sig.
The other thing you can do is to select a powder and charge weight that requires a
compressed load. The powder will keep the bullet from setting back.
There are a number of powders with compressed loads listed in the
various load manuals for .357 Sig.
Many reloaders will shy away from the .357 Sig round solely
based on tales of trouble when reloading. If you’re up for a challenge, take
these points into consideration when reloading the .357 Sig and you should see
success in your first batch.