.357sig Headspace [Archive] - Glock Talk

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dkf
10-16-2011, 12:50
What do you use to verify headspace on your .357sig reloads? Should I get an LE Wilson case gauge from Dillon, Hornady headspace gage, just use the chamber in the barrel to assure fitment?

I've read the Hornady headspace gage can give varying reading and is made of soft aluminum that distorts over time.

fredj338
10-16-2011, 13:16
What do you use to verify headspace on your .357sig reloads? Should I get an LE Wilson case gauge from Dillon, Hornady headspace gage, just use the chamber in the barrel to assure fitment?
I've read the Hornady headspace gage can give varying reading and is made of soft aluminum that distorts over time.

Is that a word???:shocked: The books will tell you it headspace on the case mouth. IMO, & others that reload this round a lot, it headspaces on the tiny shoulder as all bottleneck rounds should. Reality, it probably is held in place by the extractor BUT, get the shoulder worng & the round will not fit. It will be too far forward & not chamber or too far back & w/ a sloppy ectractor, will not fire. To date, I think every manuf has it right but RCBS, the sizing die used to not get the shoulder right & had to be milled off a few 1000ths to get the shoulder right. I use Dillon dies. Screw the sizer down to just allow a sheet of paper to pull out & they are perfect in 4 diff 357sig bbls; Sig, Barsto, Glock & EFK.

dkf
10-16-2011, 13:34
LOL, yeah "fitment" is a real word.....just don't know if its proper reloading terminology.:whistling:

I was watching the video below which made me think I should use something to insure proper headspace. I figure I would ask here before I go blow money on something I may not need. I am planning on using Lee dies for now and using the reloads in Glock barrels.

<iframe src="http://www.youtube.com/embed/KC9S1aRtDAU" allowfullscreen="" width="560" frameborder="0" height="315"></iframe>

Three-Five-Seven
10-16-2011, 18:04
Using the barrel (out of the gun, of course), put a straight edge across the standing breach and use a feeler gauge to measure the amount the case head is below the breach.

Once you've established this data point, set your sizing die to move the SHOULDER back to achieve this head space.

I, personally, go for about three thousandths. But, your milage may vary and you're really on your own because there is no data for determining head space in the way I've described.

Start with some factory rounds -- which have generous headspace -- and work down to a lower figure that allows the pistol to run reliably. Factory headspace is set to allow the pistol to continue to operate when very dirty. Something that most of us don't do and would never do with reloads in practice sessions.

(parenthetically, you'll note a WIDE variation of headspace on various brands of factory ammunition. This suggests -- to me, at least -- that factory rounds are also using the shoulder to headspace the round.)

You may (on certain brands of dies) have to shave the shell holder or bottom of the sizing die to achieve a proper head space. This is the situation with RCBS dies in my experience.

If anybody has (finally) produced an head space gauge in this caliber, it's news to me.

Since there is so much confusion within the industry about how this round actually functions as a reload, it is not surprising no one has produced a gauge to verify "truth". That is moot, of course, because you have the actual barrel at hand, which is the best gauge you could hope for. After all, that's the gun the ammo has got to run in.

fredj338
10-16-2011, 18:50
Using the barrel (out of the gun, of course), put a straight edge across the standing breach and use a feeler gauge to measure the amount the case head is below the breach.

Once you've established this data point, set your sizing die to move the SHOULDER back to achieve this head space.
.
This^^^^ The headspace gage is a good check for most guns, but some may vary & the case gage doesn't give you proper OAL anyway. Use the bbl to setup your dies.

dkf
10-16-2011, 19:20
I'll put the money towards other stuff then. Thanks.

_The_Shadow
10-16-2011, 19:26
The sizing dies from Dillon and Lee can over size and set the shoulder back too far (on 357Sig) if you screw the sized die down too much. if you have too much headspace you could see a case seperation as the case is worked under pressure during firing.

I use my barrel's chamber to setup the dies for mine also.

Bullet/neck tension is very important as well.