Case rupture - What did I do wrong???

[MosinM39]

OP, what type of crimp are you using? Can we see a pic of your crimp? My concern is that you are roll crimping or over crimping, and some of the rounds may be going in too far which could cause a failure. The 10mm auto like other auto rounds is designed to headspace on the case mouth. In extreme instances the wrong crimp could cause serious problems, especially in high pressure situations.

[F. Guffey]

OP, what type of crimp are you using? Can we see a pic of your crimp? My concern is that you are roll crimping or over crimping, and some of the rounds may be going in too far which could cause a failure. The 10mm auto like other auto rounds is designed to headspace on the case mouth. In extreme instances the wrong crimp could cause serious problems, especially in high pressure situations.

I am the fan of bullet hold; I want all the bullet hold I can get, and then there is R. Lee. R. Lee said there is no such thing as too much crimp. There was a time bullets were staked with punches. And then there was that scare, seems for what ever reason bullet were being welded to the case neck. All I wanted to know was the poundage, I wanted to know how many pounds it took to release the bullet. No one knew because they were using tensions with no way to measure it outside of interference fit.

After that they struggled for a term that could be used in place of bullet hold, like bullet grip. retention etc..

F. Guffey

[F. Guffey]

OK, this is weird! My unfired brass from this batch is .987 the FIRED brass is .980 which means my brass shrank!

I hear that all the time; reloaders claim there brass gets thicker and or thinner when they neck a case up and or down. And I always say my cases get longer and or shorten when necking up and or down.

I always say no one measures before and again after; but if they did they could start a new saying like: the case gets longer and or shorter and at the same time the case gets thicker and or thinner. Before the Internet Lyman claimed the distance from the shoulder to the case head increased when the body of the case was sized. Years after that Redding claimed they had a body die and I said 'FANTASTIC' because I knew there was no way to size the body of the case without shoulder support.

F. Guffey

[madmo44mag]

Guys I think we are over thinking this.
Flame me if you feel the need but let look at this.
He fired 23 rounds before case failure occurred.
The last 2 rounds failed.
If the chamber was to long or the brass to short he should have had a rupture before the last 2 rounds.
Also remember all the rounds will pass a plunk test.
Pistol: S&W 1076 4.25" barrel
That is a good quality gun.
I would be inclined to load 25 more rounds just like the last and see if the failure repeated again at the end of the string of 25.
If so this is a chamber issue.

[F. Guffey]

I believe I have close to 1,000 + once fired 10MM auto cases. None of them are Star-Line but I wonder how many different ways are there to make a case.

If someone examined the separated cases they would find the case head side of the separation has a tapered cup up to the point the case separated, after the separation they will find the case thickness is uniform. I know, you are all confused. But it is possible the thin part of the case locked onto the chamber and there was not enough pressure to cause the thicker case head to expand meaning when the case left the chamber the front of the case was locked onto the chamber.

Anyhow; if I had this problem I would change something that effected timing and I would use other cases.


F. Guffey

[briandg]

Guffy, I understand your point, and I've gone over that a hundred times in my mind. Sure, you are correct that there will come a point in the cycle at which time the front will be caught and the back will still be loose, but there are problems with that idea. The brass, unless it was a lousy alloy, should have been able to stretch, rather than rip off in that jagged ring.

His rounds appeared to have a few hundredths inch extra space, looking at his chamber tests, and maybe that would be enough to let it tear out, but again, it doesn't seem right.

No matter what happened, the pressure would have been gone off of that brass before it extracted. The whole cycle of firing should have been completed before the barrel started to unlink.

[Ocraknife]

I received an email from Starline, they suggested that maybe the rounds were over crimped. Who knows? I think I'm just about over the whole thing.

[Slamfire]

If someone examined the separated cases they would find the case head side of the separation has a tapered cup up to the point the case separated, after the separation they will find the case thickness is uniform. I know, you are all confused. But it is possible the thin part of the case locked onto the chamber and there was not enough pressure to cause the thicker case head to expand meaning when the case left the chamber the front of the case was locked onto the chamber.

According to Hatcherites this is how it is supposed to work, right?, the case grips the chamber and takes the load off the bolt. Because increased bolt thrust is bad, and therefore ripping the case in half causing a jam is good.

Is that not your position, more or less? You want nothing between the case and chamber other than air, don't want anything to break the friction between case and chamber.

And you don't see the contradictions either.

[TMD]

People can flame away if they want but all this talk about brass being too short or too long is complete nonsense. 10mm is no different than any other rimless cartridge. If the brass was too long there would be chambering issues, ie. slide not closing fully. If the brass was too short it will still fire just fine. Yes I know it headspaces on the case mouth but its also held in place by the extractor. Pick a 10mm auto, anyone of them and they will all feed and fire .40 S&W without all the drama. Worst case the slide may not fully cycle or you get a light strike because the extractor is worn but YOU WILL NOT HAVE CASES SPLIT IN HALF IN THE MIDDLE. Now for over crimping, generally worst case is cracked case mouth, NOT A CASE SPLITING IN HALF IN THE MIDDLE. Oversized chamber will cause brass to split length wise NOT SPLIT IN HALF IN THE MIDDLE.
Most likely cause is a bad batch of brass. Yes even companies like Starline who have a stellar reputation can occasionally make mistakes.

[Ocraknife]

People can flame away if they want but all this talk about brass being too short or too long is complete nonsense. 10mm is no different than any other rimless cartridge. If the brass was too long there would be chambering issues, ie. slide not closing fully. If the brass was too short it will still fire just fine. Yes I know it headspaces on the case mouth but its also held in place by the extractor. Pick a 10mm auto, anyone of them and they will all feed and fire .40 S&W without all the drama. Worst case the slide may not fully cycle or you get a light strike because the extractor is worn but YOU WILL NOT HAVE CASES SPLIT IN HALF IN THE MIDDLE. Now for over crimping, generally worst case is cracked case mouth, NOT A CASE SPLITING IN HALF IN THE MIDDLE. Oversized chamber will cause brass to split length wise NOT SPLIT IN HALF IN THE MIDDLE.
Most likely cause is a bad batch of brass. Yes even companies like Starline who have a stellar reputation can occasionally make mistakes.

Starline's position at this point is that I over crimped the rounds and or over charged them. They based the overcharge assertion on the incorrect assumption that I used Hornady 180 grain XTP bullets which i didn't - still, I don't know if that really makes any difference.

At this point, I have to decide if I should break down 125 or so loaded rounds and reload them much lighter or recover the powder and bullet and toss the brass. I also have 50 more unfired brass from the same batch from Starline that I don;t know what to do with.

[TMD]

Send the unused ones back to Starline along with the split cases and see what thay say.

[Ocraknife]

Send the unused ones back to Starline along with the split cases and see what thay say.

I'll ask if they want them. Right now, their position is that I did something wrong and I can't really say that I disagree with them at this point.

[Clark]

I had a 10mm case break in half in a work up. The cases with less powder and the cases with MORE powder did not break.

It was more than 10 years ago. That is a lot of computers and cameras ago. I can see I filled it with cerrosafe to try to figure out why it failed. I fail to see the purpose in that test now.

[Ocraknife]

I had a 10mm case break in half in a work up. The cases with less powder and the cases with MORE powder did not break.

Strange. Maybe it's some kind of Tesla mechanical resonance thingy.

[briandg]

That is the very first time anyone has actually stepped forward and said that they have even seen something like this. Whatever it is it's uncommon,

I genuinely believe that over crimping and your fault is bull pooters. You showed no crazy level of crimping in your unfired rounds. The idea that it was so hard to pull through the crimp that it pulled the case apart is a plausible explanation, but seriously, guys, if a serious, heavy crimp on revolver cartridges does it, why in the world would it pull apart for a light taper crimp on this?

A very, very wise and successful attorney passed on this quote to me.

It's not my fault until a jury says that it is.

[briandg]

I think that you should send them another message, tell them that you don't accept their explanation, since there is no evidence that either one of those things happened, and that you want the brass replaced with a package of new brass regardless of what they believe.

Again, I just keep thinking about all of the millions of rounds of heavy magnum revolver rounds fired every year, with nothing at all supporting that case mouth, and nobody here, or anywhere else, has ever had this happen, with new or used brass.

You don't seem to mind believing that you just made a mistake, and that's alright, but honestly, what is more important than any of the other things here is to find an explanation to prevent it from repeating, and I'd like to see that. If you continue to shoot that brass even after "correcting" what they believe is the problem, and you have another failure, we'll know that they're talking bullhockey. If you start using another brand, it's not going to offer any proof unless you blow out another piece of brass, but IMO, pulling down the bullets and starting over with fresh brass is the best thing to do.

I've reached the point where I don't have anything new to offer, I think, so I'm going to bow out.

Anyway, I've got a really great cigar going and a lot of email to catch up on. I hope you solve this and have a really good time with that gun, they were really nice.

[243winxb]

Time to stop talking and start shooting, with a lower powder charge in new unused brass, with a very light taper crimp that just removes the flare on the case mouth.

[Nick_C_S]

I was using jacketed flat points not XTP bullets.

I know.

I don't know if that makes a difference or not.

Evidently, not much at all; otherwise, Hornady wouldn't publish the same load data for them - with the same OAL. For all intents and purposes, they're the same bullet. Hence, my posts.

Several have questioned that 11.0 grains could be an over charge. Such is highly unlikely, is my point.

Just a thought: If you want to mail me a few pieces of your brass, I'll load 'em up (11.0 or 11.7 grains - whichever) and shoot them through either of my Glocks to see what happens. I'll even mail them back - regardless of condition .

No obligation. It's perfectly okay to decline. Just putting it out there. PM me if interested.

[Ocraknife]

Evidently, not much at all; otherwise, Hornady wouldn't publish the same load data for them - with the same OAL. For all intents and purposes, they're the same bullet. Hence, my posts.

Several have questioned that 11.0 grains could be an over charge. Such is highly unlikely, is my point.

Just a thought: If you want to mail me a few pieces of your brass, I'll load 'em up (11.0 or 11.7 grains - whichever) and shoot them through either of my Glocks to see what happens. I'll even mail them back - regardless of condition .

No obligation. It's perfectly okay to decline. Just putting it out there. PM me if interested.

Sure. I'll need to deprime them first but I'll ship you some.

[Ocraknife]

I think that you should send them another message, tell them that you don't accept their explanation, since there is no evidence that either one of those things happened, and that you want the brass replaced with a package of new brass regardless of what they believe.

Again, I just keep thinking about all of the millions of rounds of heavy magnum revolver rounds fired every year, with nothing at all supporting that case mouth, and nobody here, or anywhere else, has ever had this happen, with new or used brass.

You don't seem to mind believing that you just made a mistake, and that's alright, but honestly, what is more important than any of the other things here is to find an explanation to prevent it from repeating, and I'd like to see that. If you continue to shoot that brass even after "correcting" what they believe is the problem, and you have another failure, we'll know that they're talking bullhockey. If you start using another brand, it's not going to offer any proof unless you blow out another piece of brass, but IMO, pulling down the bullets and starting over with fresh brass is the best thing to do.

I've reached the point where I don't have anything new to offer, I think, so I'm going to bow out.

Anyway, I've got a really great cigar going and a lot of email to catch up on. I hope you solve this and have a really good time with that gun, they were really nice.

Thank you for your post. I appreciate what you are saying. I plan to do a little more experimenting. If I feel that the problem is bad brass after doing some double and tripple checking then I'll ask them to replace the brass. Frankly, I"m surprised they haven't already offered.

Perhaps they don't want to for fear that it could be construed as an admission of guilt or don't feel it's warranted or it hasn't occurred to them.

[sdrnavy91]

check your charge on a digital scale... you might see that your mechanical scale is off... I done the same thing that you did with my .40... I couldnt figure it out. I got a Hornady digital scale, and my charge was 1.5 grains too heavy on that mechanical scale.. I have been using that Lee mechanical scale for 10 years, I dropped it one day. It was still in good shape.. so i kept using it.. evidently it wasn't. I have been using a digital scale ever since and checking the calibration everytime I use it. I hope I helped with my bad experience.

[Tinbucket]

I didn't read all the numerous replys. If i cover some of the same territory,I appologize
*Plated brass is more brittle than plain brass.*
Plated brass won't adhere to the chamber like brass. It's slick. The reason they plate it is not for the pretty but for long life in the pistol belt . Won't corrode so easy and it won't stick in the chambers as easy.
*Reloaded cases, probably many times.*
Separation at the point where the bullet end seats.
*If you had run a sharpened bent wire or pick on the inside of the cases, prior to reloading this this time you may have/probably would have felt a separation line developing.*
High charge but not too high probably.
Front ,of case ,still adhering to chamber as the extractor yanked the case out, breaking at that line, leaving the front half, in the chamber or coming out, still attached at a ragged point of two.
Fix 1Stronger recoil springs. 2Check cases before reloading.
Make sure your chamber is in good shape. A bit of powder left after firing will usually be pushed along by the next cartridge, or was it a bit of the case?
And last make sure you don't leave any case lube on the caartridges.
imo and after I think about it I may come across something different

[Mauser69]

I didn't read all the numerous replys. If i cover some of the same territory,I appologize

I didn't read your reply once I saw that you didn't read anybody else's reply.

[Ocraknife]

check your charge on a digital scale... you might see that your mechanical scale is off... I done the same thing that you did with my .40... I couldnt figure it out. I got a Hornady digital scale, and my charge was 1.5 grains too heavy on that mechanical scale.. I have been using that Lee mechanical scale for 10 years, I dropped it one day. It was still in good shape.. so i kept using it.. evidently it wasn't. I have been using a digital scale ever since and checking the calibration everytime I use it. I hope I helped with my bad experience.

Good idea. My Hornady digital scale says that my rounds are at or slightly below the weight I was targeting.

[F. Guffey]

Good idea

I suggest you purchase a box of new over the counter factory loaded ammo and then to the range and test fire the new ammo. If you insist on reloading I suggest you change something, I would start with the powder AND! I would use the fired cases from the new over the counter factory once fired cases.

F. Guffey