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Not
all 357 SIG Brass Is Created Equal Disclaimer: The following information is what works
for me. I am not responsible for your actions. Always refer to factory
firearms instructions and precautions, refer to official reloading
manuals when reloading, and especially be aware of Local, State, and
Federal Firearms Laws. Use your common sense. You are responsible for your
own actions! I measured the dimensions of different brands of once
fired 357 Sig brass, reloaded with the only changing
variable being different brass brands, and measured the velocities. I loaded
all six brands at the same sitting. I did not have any once fired Starline
brass, although I decided to measure and test brand new Starline brass as a
proof point as well. I tried my best to keep the taper crimp on each brass type
at right around .378, with the same light crimp mark on the bullet.
Notice that the new Starline brass had a
perfect SAAMI shoulder measurement of .6820. After brass is fired, it becomes
.6900. Notice that the SAAMI neck length is .15 while I
measured .14 for the new and fired brass. Now this could be my fault, because
obviously SAAMI thinks it is .15. Notice the pressure ring (the widest part of the
brass) between the SAAMI standard, the new brass, and the fired brass. Notice that FC and RP brass is very close to needing
trimming. I would have to measure every brass to make sure it did not need
trimming. Notice the neck thickness. Now I had a heck of a
time measuring the neck with my digital caliper. So I’m sure my measurements
are not perfect. Nevertheless, it should give you a rough idea. So why was Hornady so slow? Why were Starline
and So what caused the difference between Speer and
RP? Their weight and neck thickness is kind of similar, although the RP brass
is longer. Or, maybe the larger pressure ring in the Speer brass caused less
pressure build up? Here's a pointer to a White Paper with some good detail of
Speer 357 Sig ammo changes, including brass changes: http://Speer
Brass White Paper Report Is heavier brass better than lighter brass? Maybe not
if the light brass has been tempered and treated for strength. Although in the
case of Hornday brass, it appears to have the widest velocity spread and the
highest standard deviation. It also has the worst bullet setback rating in
general. Bullet
Setback Chart I then did a bullet setback test with each brand using
a standard West Coast 124 grain flat point plated bullet and also a test with a
light cannelure groove on a bullet. I personally believe the cannelure groove
is the fix for having a short neck. Factories can use a cannelure groove or
some kind of sealant/glue for the same purpose.
Note: For tests 1 through 5, I used 45 lb of pressure on a weighing scale.
The final test was to apply pressure until the bullet collapsed into the case.
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