357 Case Head Separation

[DsGrouse]

I used to get similar but not as bad marks when I loaded military .38 special cases using a carbide sizing die. I shot most of that brass many times using a load of 5.5 of Unique with my home cast hard 160 grain SWC. . I shot it in my Colt Trooper . I never had a loose primer or head separation of course that was shot in a revolver.

Neither have I. some of my brass has many reloads. Which makes me thing failure of that case due to work hardening.

DsGrouse - thanks for the pressure info. What exactly is GRT? Looks like it might be a use tool for hand loading.

Gordon's reloading tool.
https://grtools.de/doku.php

Gordon Passed away a few years ago, long before I found the software. It's kind of like Quick Load. It's modeling software that helps you dial in loads. The community keeps it going.

In this instance, I was needing to work up a load above the listed max for 357 mag using win 244. GRT helped me figure out the pressures I was actually achieving.

You do that in part by measuring fired brass from that weapon. Put your spent brass on the scale, zero it out, fill it up to the brim with water, and weigh it again.

In the calculations I showed you, I used the volume of my spent brass. It's imperative that you make the measurements using your rifle.

GRT has a discord channel that has been very helpfull.

[azdover]

Thanks. I'll check out the website.

[CT_Shooter]

Gordon's reloading tool.
https://grtools.de/doku.php

Gordon Passed away a few years ago, long before I found the software. It's kind of like Quick Load. It's modeling software that helps you dial in loads. The community keeps it going.

I wondered what you were using. Thanks for sharing the link.

I installed it and have been playing with it for the last hour or so. I plugged in values from Hornady's Ninth and it provided data that was pretty close to the manual. Then I plugged in values for my barrels and reloads. I was especially interested in learning how my reloads performed in my little King Cobra 2". Very cool.

[DsGrouse]

Gordon's reloading tool.
https://grtools.de/doku.php

Gordon Passed away a few years ago, long before I found the software. It's kind of like Quick Load. It's modeling software that helps you dial in loads. The community keeps it going.

I wondered what you were using. Thanks for sharing the link.

I installed it and have been playing with it for the last hour or so. I plugged in values from Hornady's Ninth and it provided data that was pretty close to the manual. Then I plugged in values for my barrels and reloads. I was especially interested in learning how my reloads performed in my little King Cobra 2". Very cool.

So there is a spot for Gas Leak, that relates to revolvers. Besure to use your fired cases from that gun. (possibly each chamber)
the manual is pretty good. the discord channel is helpful.

The obt, is pretty good. If you tie it in with your chrono data, and shot group. It can help calculate the most likely accurate charge based on your COAL, powder, and bullet combo.

[DsGrouse]

oh i forgot to mention there are a number of good youtube vids on using GRT.

[azdover]

Had another 357 Federal case head separation, this time in a Ruger Blackhawk with a mid power load of HS-6 with a 125 gr bullet. Guess I'm on a roll.

I just got a set of Clymer go/no-go gauges and both guns check good, so it's probably not a headspace issue.

Unfortunately, as far as I can tell, GRT won't work with Apple products so that's out for me.

Guess I just got a bad batch of Federal brass or my reloading technique leaves a little to be desired. As Forrest Gump says "It happens."

[DsGrouse]

https://thefiringline.com/forums/showth ... p?t=601578

I did a little googling.

https://www.levergunscommunity.org/view ... hp?t=72269

https://enoughgun.com/forum/viewtopic.php?f=3&t=14125

[CT_Shooter]

Had another 357 Federal case head separation...

Azdover, this subject was new to me with your initial post. I'd never heard of that happening to a case before. And seeing that ring on my own once (or more) fired brass was surprising. Thanks for starting the thread.

Incidentally, that ring does NOT exist on loaded -- but never fired -- Starline brass, which suggests it may be created by the decapping/sizing die (which the Starline brass did not see) and be unaffected by the FCD die (which it did). Just an observation.

I'd like to know if this has ever been discussed in any of the many Reloading Handbooks as a concerning issue. I don't recall reading about it.

[DsGrouse]

Had another 357 Federal case head separation...

Azdover, this subject was new to me with your initial post. I'd never heard of that happening to a case before. And seeing that ring on my own once (or more) fired brass was surprising. Thanks for starting the thread.

Incidentally, that ring does NOT exist on loaded -- but never fired -- Starline brass, which suggests it may be created by the decapping/sizing die (which the Starline brass did not see) and be unaffected by the FCD die (which it did). Just an observation.

I'd like to know if this has ever been discussed in any of the many Reloading Handbooks as a concerning issue. I don't recall reading about it.

From what i understand. That ring is from the carbide insert in carbide sizing and crimp dies

There is a bevel on those carbide rings that limits how much sizing the die can do. It is why you see a lot of coke bottle style tapered and straight walled cases.

The "fix," as i understand it, is for full length steel sizing and crimp dies, as they dont have that bevel or carbide ring.

The downside of that is most of those dies will require a lube step.

[azdover]

If anybody has any measurements on their resized 357 brass, please post it up and what brand dies you're using. That will give me some info to compare to my brass.

After searching the web and considering everyone's advise, I'm leaning toward a bad batch of Federal brass in this case. I've been using this same resizing die for the past 25-30 years and never ran into this before with everything from mouse fart lo full power loads. I'll keep an eye the situation and if it continues, especially with my BBS, I'll contact Henry and see about sending it in for evaluation the chamber. I'm sure they'll fix it if it's oversized.

Thanks for the pointers and help,
Pete

[220]

Just looking at saami chamber and cartridge specs for 357 and did not realize head space was so generous on 357.
Chamber rim thickness is 0.060 + 0.010 giving maximum permissible 0.070, Maximum cartridge rim thickness is 0.060 - 0.011.
In effect with a minimum sized case in a max chamber you could have 0.021 and still be within spec.

22 hornet is notorious for case head separations even with guns and ammo within spec, runs similar pressure and head spaces on the rim like 357. Maximum head space with it is 0.018. I know a lot of hornet owners will only use specific brands of case with the best rim thickness to suit their chambers.

Given your guns have checked out within spec for headspace I would be taking some rim thickness measurements on the brass to see if it is undersize. With a rimmed cartridge it is impossible to change the headspace by resizing it is entirely dependent on the chamber and brass rim thicknesses. You have eliminated the chamber being oversize so checking the brass is not undersize would be the next step.

Looking at your original measurements your chamber seems within spec, maximum chamber sizes are listed as 0.3809 at the base and 0.3801 at the mouth with + 0.004. so with you biggest fired case measurement at 0.3830 still within tolerance.

Your reloading dies also seem to be within spec, ammo size is given at 0.3790 - 0.006 so a range of 0.3790 to 0.3730. With your resized and loaded ammo all being consistently 0.3775.
Even if one of these was out I would expect longitudinal splits in the case after reloading a number of times as the brass got worked not head separations.

Case rim thickness is the only thing you havent checked

[Bill.68]

How much of that SWC is inside the case compared to their other bullets? That could spike pressure. When Im loading with PP I very frequently check to see how my powder measure is behaving. PP just seems to not dispense as well as alot of other powders do even though it looks as though it would.
That "cannalure" looking ring around that case is in the trash as soon as I see them, its not normal so in my book its not safe. I just loaded some Xtreme bullets this weekend for the first time and they too happened to be for the 357 but I bought the 125gr FP and also followed their load data and used 8.6gr of VVN340 and was impressed. I bought some plated to shoot in my 586 no- so I would have an easier time cleaning bs cast I normally shoot. Im happy with their bullets.