Case separation 357 mag

[chefeffect]

Howdy,

Straight off the bat I am a newby to loading, but have had some fun working up a load for my 357 mag rossi 92. I bought this gun with idea of having a fun accurate centre fire rifle that I could also plink with. I have had lots off issues getting a good factory round that works well in my rifle.

Long story short, with lock down, and not much to do, I decided to start reloading and see if I could get a good cheap round happening. And to make it even more cheaper started casting my own projectiles.

I have cast Lee 358-158-RF with wheel weight lead and they have come out 164 grain. I have also coated these with Hi-Tek super coat. I have worked up some loads from AR2205 10.5grain at half grain intervals up to 17.5 grain. At 15 grain they started to not tumble and started to group better. By 16.5 they were grouping the best but still the odd flyer. Heading up to 17.5 grain and they were spraying all over the joint so I backed down to 16.5 grain and found this shoots well. Fired maybe 50 rounds with no issues but still having problems with this Weaver 4 MOA red dot I bought and try to sight the mongrel thing in.

I have fired maybe 50 rounds at 16.5 grain and its been fine. Last night I decided to use some once fired brass B & S which I have loaded in this brand previously and had no issues. I started getting case separation as per the attached photo. I also can notice a fine line on the loaded cases not sure if this is a bad batch or if I have stuffed up. I am using digital scales and am 99% sure my gun powder measure is spot on.

I had some issues with the rounds cycling through my lever action so I I seated the boolit ever so slightly deeper so the case neck would fit in the cannelure better, and an ever so slightly firmer crimp. You could hardly notice the difference, but they now cycled very well through the lever action.

As you can see in the photo some cases separated in half. I could feel when it happened after firing because they did not kick as much. Maybe every second case did this. I cleaned the rifle and shot three more with no issues but decide to call it a day and try and figure out whats happened.

I don't have all the equipment I want yet including a tumbler hence the non shiny brass, I have been using NRA recipe for cleaning. I also need a debburing tool which is in the post. Hence the rough looking edges on the case necks. I borrowed a debburing tool for the first batch of rounds surly this wouldnt be the issue?

Any thoughts would be much appreciated.

20200721_155440.jpg (3.02 MiB) Viewed 4429 times

[Blr243]

I can’t shed any light on why this has happened ....Never heard of it before in a 357 case ...I have done a stack of 357 loading cast and jacketed, target and hunting , rifle and pistol .38 cases and 357 cases ..I used the same brass over, an over , and over ..it seemed to last forever ....I’m very keen to hear others thoughts on this Situation

[in2anity]

TBH seems a bit surprising considering it headspaces off the rim. Nevertheless if you honestly think the recoil feels different on the separated ones, it has to be a bolt flex issue right? That combined with perhaps a sloppy chamber that tends to “grab” the front of the shell upon recoil, or perhaps extraction... Just curious, how many times had you recycled your brass before this started happening?

[chefeffect]

This batch I have only loaded once, and I fired them as factory loads myself.

I fired about 20 factory loads today and they were all fine

Edit: I think the the change in kick is because of the vent holes in the bolt releasing after the case cracked in half. The cases came out easy also.

[in2anity]

Right so the brass is failing at combustion time, indicating the case is moving rearward more than it should. Seems like a sloppy lockup.

[chefeffect]

I might take to the gun smith tomorrow. It's only just started doing it with this new batch I loaded, I assumed I had done something wrong.

I didnt have any issues with factory ammo before or after this incident. Did you see the photos of the strange ring around the base of the loaded ammo? It's almost exactly were the others busted.

[in2anity]

Yes what if there are lips in the chamber there from poor/rushed machining? Especially with hot loads, brass fire forms and “catches” on recoil/extraction. Perhaps you could shove a reamer up it to polish it?

Also, how about getting a barrel cam? There are cheap ones these days.

[chefeffect]

All very possible, I will look into those suggestions. Thank you!

[Oldbloke]

ADI lists 16gr AR2205 max losd for 158gr.

17.5gr is high? But I suspect there is more to this

[bladeracer]

You could try putting a shim between the bolt face and case head to reduce headspace and see if that helps.

Have you chronographed these loads?

[Bugman]

The image of the loaded ammo shows lead shavings around the rim of the brass. Did this happen when loading the projectiles? If not, it appears that you need to ever so slightly increase the case mouth flare so when the projectile is seated it doesn't shave some of the lead off. The separation appear to be possibly excess pressure.

[chefeffect]

Morning,

Yes 17.5 grain was pretty high other than terrible accuracy no dangerous signs to cases. I found 17.5 grain max in an old loading book. One even had 11.5 grain as max?? Still think it's something else also. I might back off to 16? Strange I have shot 50 rounds at 16.5 and no issue. 5 @ 17 grain and 5 @ 17.5 grain and no issue.

No chronograph as I don't have they equipment.

I was worried the case flare was too much originally as I struggled to get it in the seating die. I will try flaring some more. I didn't debur so this may have caused it also. Or the crimp was too tight??

Many thanks guys.

[straightshooter]

Chefeffect
The first picture shows a bright ring on your brass in about the same position where the second picture shows separations.
Ignoring the possibility that those bright rings could be due to rubbing in a container such as a MTM ammo box then those bright rings could be evidence of incipient separation. If so this is what is happening.
At the instant of igniting the primer, the case is pushed forward as far as it will go, due to the force of the primer, and the primer cup will back out as far as the locking arrangement will permit it. At this point in time the maximum amount of clearance exists between the boltface and rim. As firing progresses and pressure builds up within the case the front part of the case grips the chamber more than the the rear part of the case grips the rear part of the chamber resulting in the case stretching to meet the boltface and reseating the primer in the process. At the same time the thinner parts of the case expand to meet the chamber walls only to then spring back slightly when pressure is reduced.
The problem arises when you full length resize. Now that junction between where the case expands and doesn't expand gets thinner until it is unable to sustain any more stretching.
A possible fix is to set back the barrel to achieve zero headspace with the thinnest rimmed brass, but that will mean that thicker rimmed brass will be difficult or impossible to chamber. It will also mean many mods to the rifle all adding to expense.
My suggestion is this:
1 Resize the cases only just enough so the projectile is lightly gripped and rely on the crimp for it to stay in place. The effect of this is to provide some resistance to movement of the case on firing.
2 Use the slowest powder suitable so as to keep pressures low and minimise the grip of the case neck on the chamber. Not cleaning your brass also might help.
3 The obvious thing is to stick with brass that seem not to have problems.

Lastly carefully consider the pitfalls of any of the halfbaked suggestions being made (including mine) before making any irreversible change.

[chefeffect]

Morning straightshooter,

That all makes sense. This gun is frustrating me and I don't particularly want to spend more on it, so I appreciate the suggestions.

The bolt closes very tight on the chamber. I had some issues cycling the ammo in the rifle and also full length resizing so I used a roll pad with wax so the cases would resize easier. This is the first time I rolled my cases on a pad with bullet wax maybe I used to much and it's not gripping in the chamber now?

[Oldbloke]

Morning straightshooter,

That all makes sense. This gun is frustrating me and I don't particularly want to spend more on it, so I appreciate the suggestions.

The bolt closes very tight on the chamber. I had some issues cycling the ammo in the rifle and also full length resizing so I used a roll pad with wax so the cases would resize easier. This is the first time I rolled my cases on a pad with bullet wax maybe I used to much and it's not gripping in the chamber now?

I've never loaded straight wall cases. But lube on the case is normally a no no. Must be clean and dry.

[in2anity]

I agree OB. chefeffect get yourself a carbide die and skip the lubing/cleaning part. For all my reloading, at most, occasionally I wipe the cases with a rag and a low-residue cleaning agent, such as rubbing alcohol (providing you're not doing tonnes at a time).

[chefeffect]

Morning Oldbloke,

I had read that wax in not required. I was worried I was going to break my press as I had to force the case in and out of the die excessively.

I might try cleaning the imperial wax off the ammo I still have loaded and try them again.

I also cleaned the rifle after I noticed the separation and then fired 3 shots with shells that had visible lines on the cases like in the photo and none separated.

I wonder if the wax was building up in the chamber? It only started happening after about 20 rounds.

[Oldbloke]

Lube while sizing and remove it later as in2anity said.

And, yes clean the chamber to remove all lube.

You may need to try a couple of solvents.

For 30-06 & 223 I just lube with diff oil. Wipe off after loading with a rag, sometimes a bit of kero or turps.

[chefeffect]

Thanks everyone.

I gave the bore a very good clean and used a small amount of acetone to carefully clean each of the ammo. Shot 20 rounds of the same batch without any issues. Clearly the wax was stuffing it up.

Again thanks heaps.. glad it's sorted now.

[trekin]

Howdy,

Straight off the bat I am a newby to loading, but have had some fun working up a load for my 357 mag rossi 92. I bought this gun with idea of having a fun accurate centre fire rifle that I could also plink with. I have had lots off issues getting a good factory round that works well in my rifle.

Long story short, with lock down, and not much to do, I decided to start reloading and see if I could get a good cheap round happening. And to make it even more cheaper started casting my own projectiles.

I have cast Lee 358-158-RF with wheel weight lead and they have come out 164 grain. I have also coated these with Hi-Tek super coat. I have worked up some loads from AR2205 10.5grain at half grain intervals up to 17.5 grain. At 15 grain they started to not tumble and started to group better. By 16.5 they were grouping the best but still the odd flyer. Heading up to 17.5 grain and they were spraying all over the joint so I backed down to 16.5 grain and found this shoots well. Fired maybe 50 rounds with no issues but still having problems with this Weaver 4 MOA red dot I bought and try to sight the mongrel thing in.

I have fired maybe 50 rounds at 16.5 grain and its been fine. Last night I decided to use some once fired brass B & S which I have loaded in this brand previously and had no issues. I started getting case separation as per the attached photo. I also can notice a fine line on the loaded cases not sure if this is a bad batch or if I have stuffed up. I am using digital scales and am 99% sure my gun powder measure is spot on.

I had some issues with the rounds cycling through my lever action so I I seated the boolit ever so slightly deeper so the case neck would fit in the cannelure better, and an ever so slightly firmer crimp. You could hardly notice the difference, but they now cycled very well through the lever action.

As you can see in the photo some cases separated in half. I could feel when it happened after firing because they did not kick as much. Maybe every second case did this. I cleaned the rifle and shot three more with no issues but decide to call it a day and try and figure out whats happened.

I don't have all the equipment I want yet including a tumbler hence the non shiny brass, I have been using NRA recipe for cleaning. I also need a debburing tool which is in the post. Hence the rough looking edges on the case necks. I borrowed a debburing tool for the first batch of rounds surly this wouldnt be the issue?

Any thoughts would be much appreciated.

20200721_155440.jpg

Did you messure case capacity of the S&B cases and compare that to the capacaity of your other cases. The same load in a case with lesser capacity will lead to excessive pressure, 0.1 or 0.2 of a grain can be the difference between safe and excessive with a pistol round.
Seating the projectile deeper into the case can cause a increase in pressure (for the above reasons), as can a slightly tighter crimp.
Incipient separation can happen with the first firing, even with new rounds/brass, especialy in firearms with inherently weaker actions such as levers.
Check the rim thicknes of the S&B cases and compare with the other cases. Cases with thinner rims can give excessive head clearence which will show the same as excessive headspace.

[marksman]

case lube must be removed from ammunition before firing it, failure to do so prevents the cases from momentarily gripping the chamber walls during firing, increasing the breechface thrust pressure to beyond safe levels, it will cause excessive headspace to develop

interesting thread

[in2anity]

case lube must be removed from ammunition before firing it, failure to do so prevents the cases from momentarily gripping the chamber walls during firing, increasing the breechface thrust pressure to beyond safe levels, it will cause excessive headspace to develop

interesting thread

Marksman I think you might have nailed it there.

[straightshooter]

in2anity and marksman
Think about it very carefully.
If the case has residual surface lubricant then there will be reduced friction between the case and the chamber walls so at the instant of peak pressure the whole case will have been forced into intimate contact with the boltface and there will not be any localised stretching of the case wall. Thus none or only slight development of a separation depending on the coefficient of friction of the lubricant and the surface finish of the chamber walls.
The increase in bolt thrust will be roughly equal to the yield strength of the cross sectional area of that portion of the brass case that otherwise would develop a separation.
In other words not enough to worry about unless you are already in or near unacceptable pressures to start with.

[in2anity]

in2anity and marksman
Think about it very carefully.
If the case has residual surface lubricant then there will be reduced friction between the case and the chamber walls so at the instant of peak pressure the whole case will have been forced into intimate contact with the boltface and there will not be any localised stretching of the case wall. Thus none or only slight development of a separation depending on the coefficient of friction of the lubricant and the surface finish of the chamber walls.
The increase in bolt thrust will be roughly equal to the yield strength of the cross sectional area of that portion of the brass case that otherwise would develop a separation.
In other words not enough to worry about unless you are already in or near unacceptable pressures to start with.

Perhaps you are right SS, but I'm not argueing hither and tither. Basically I reckon the rear locking lugs combined with a potentially sloppy lockup are a contributing factor however. One way or another, I think the lube combined with the hot loads is accentuating this defficiency. That's enough of a conclusion for me.

[Oldbloke]

"I have fired maybe 50 rounds at 16.5 grain and its been fine. Last night I decided to use some once fired brass B & S which I have loaded in this brand previously and had no issues. I started getting case separation as per the attached photo."


I have just read through this again.
We know we should clean the Lube off the brass for the reasons mentioned earlier by Marksman and straight shooter. (Increased pressure against bolt face)

But I'm unsure if the lube is the issue.

I note that the issue started after he changed the brass . My bet is its the B&S brass.

It could be a coincidence that he c l eaned off the lube.

Sooo, were the latest loads that shot ok B&S?

[Gamerancher]

Lube residue on cases can lead to case separation as has been alluded to, usually about halfway along the case walls. ( like yours )
Recently had a fellow shooter lose a bunch of .45-90 cases at a BPCR match due to separation. The culprit was a wet chamber from wet wiping with "bore-pigs" between shots. He started running a dry patch after the pigs and the problem ceased.
I've also seen case separation from over-length cases, when jammed in the leade, the bullet wants to take the brass along for the ride upon firing.
Your cases don't appear to have done that.
As someone has earlier pointed out though, you need to make sure you have enough flare at the case mouth to start cast bullets when loading to avoid "shaving" lead off the side as is evident by the lead smear on the outside of your case mouth and loaded rounds pictured. The base of a cast bullet is the most crucial part when it comes to accuracy and any defect will lead to "flyers" and can also cause leading of your barrel due to gas cutting.
It looks like your crimp is a bit on the "overdone" side of things as well. You only need enough to hold the bullet in place under recoil and to ensure that the case mouth doesn't catch on the edge of the chamber on loading.
'92's and their clones can be made to shoot quite well with cast bullets, try loading on the mild side. Myself and others who compete with these rifles have found that they shoot very well when velocities are kept around the original black-powder velocity, after all, that's what they were designed to shoot. ( Yes , I do realise that the .357Mag was never a blackpowder cartridge )