Can anyone tell me where this cartridge headspaces on my 229? I've heard the case mouth and the shoulder. I have been reading articles about the RCBS dies not bumping the shoulder back enough. Thanks in advance. Great gun by the way-a nice addition to my 226, 227, and M11-A1.

It headspaces on the case mouth; I'd be interested in knowing the source that said it headspaces on the shoulder.

mesabi


From The High Road:
Size it to headspace off the shoulder. We have plenty of .357 Sig reloaders here can can help.

Thank you for your quick answer. I looked in my barrel and did not see a shoulder. I have seen this argument 50/50 mouth/shoulder.

quote:

Originally posted by inspector710:
I have seen this argument 50/50 mouth/shoulder.

Exactly.
“It’s a bottleneck cartridge: headspace on the shoulder!”
“It’s a pistol cartridge: headspace on the case mouth!”

Wiki, not the greatest source, says:

quote:

Several sources have published contradicting information regarding .357 SIG headspacing.[4] This is due to the cartridge having been originally designed as a .357 (9.02mm) round, but then rapidly adapted to the .355 (9mm) bullet. According to the official C.I.P. (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portatives) 2008 revised documents, the .357 SIG headspaces on the case mouth (H2).[5] Some US sources are in conflict with this standard.[6] However, the cartridge and chamber drawing in the ANSI/SAAMI American National Standards also clearly shows the cartridge headspacing on the cartridge mouth.[7] Likewise, US reloading supplier Lyman has published that the .357 SIG headspaces on the case mouth.

https://en.wikipedia.org/wiki/.357_SIG

Easy enough to figure out. Trim the neck off a case, just above the shoulder. Insert it in your chamber. Next, try an untrimmed case. If they both go the same depth into the chamber, it is head spaced off the shoulder.

I'll try it.

I can tell you many moons ago when 357Sig first came out, there was no new 357Sig brass for sale. Many of us reformed 40S&W brass(a shorter case than 357Sig) and loaded it to 357Sig specs. It worked like a champ. There is no way that cartridge, which was shorter that 357Sig, was headspacing on the case mouth.....it was headspacing on the shoulder.

Every reloading manual I have (Sierra, Speer, Nosler, Hornady, Lyman, Western) says that it headspaces off the case mouth; several caution against trying to use .40 S&W brass, as have several articles in Handloader magazine.

I'll leave the experimental learning at high pressures to others and rely on published data from an actual ballistics lab.

Hmm..
The problem with headspacing on the.357 Sig comes from confusion on the proper way to measure 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 .357 Sig

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 fired case. 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.

There are 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