If a manufacturer has such large tolerances so a case can blow up it is not only surprising it is also the worst crap. Are you sure that your brother didn’t mix up the powders? It can happen to the best.

/Peter

Doubtful the powder was mixed up. He cranks them out on a turret press and the round that blew was more than halfway through a box of 50. Every few rounds he verifies overall length and weight as well to make sure nothing has changed. I've reloaded with him before and his quality control is pretty high. I've fired a lot of his reloads over the years without a problem. I've even run them through the chrono and the velocity spreads were tighter than factory loads.

I mentioned it on another thread, but one of the things damaged on the gun was the extractror, which had broken about a third of the way back. However, I don't know if the burst blew the extractor apart, or the extractor broke on the previous round, leaving a weak spot open on the case head. I hadn't really thought about headspace until I read the article.

As far as the ammo goes, the cases were originally American Eagle, which isn't necessarily top quality. Don't know if that had anything to do with it or not.

[ This Message was edited by: expatriate on 2003-03-20 18:55 ]

Nice to hear that your brother knows what he’s doing and that he has a thorough quality control. You have probably heard the expression “there is two kinds of reloaders bold reloaders and old reloaders, but there is no bold reloaders”.

I meant the quality of the rifle and didn’t mean the quality of the case (even though I don’t have high thoughts about American Eagle). If the case is calibrated in the full body die or even better in a neck seizer it would fit the camber just fine with no head space problem. So my guess is that the error is in the rifle. The fact that the extractor was broken strengthens my conclusion. Choose another brand in the future;).

/Peter

Was there a chance that a half loaded cartridge made it in to the mix. Some times the progressive presses will load an empty or reduced load by accident. Although you can usually tell the difference in an empty load, a half load will make it through the QC most times. This load basically will lodge the bullet in the barrel, eject the casing, load the next casing, then cause the barrel to rupture when you pull the trigger again. This can happen in factory loads as well.

Headspace will and does cause the problem you spoke of. You say your brother is a very experienced reloader, so I imagine he does frequently check the case length? Which is quite different than overall length. As cases are resized they stretch (unless you trim them) eventually becoming so long they will bottom out in the chamber, thus exposing more of the case rear, at the breech causing a dangerous headspace condition. This sometimes can be evident to the eye by seeing a larger area just forward of the extraction groove. This may or may not happen with a single shot of such a round but continuing to fire such rounds will continue to weaken the barrel and eventually cause a blow out. This is a common occurrence for semi auto pistols using reloads. This condition raises pressures dramatically.

Most ammunition sold is just under the maximum trim length. Some never fired brass is already at the maximum. After firing and resizing the case just a couple of times (sometimes only once) it will be well over this maximum. I can’t remember off hand the maximum trim length for the .40cal but it should be (including all pistol ammo) trimmed back .005 to .010 inches less than the maximum length. Rifle ammo can be trimmed back .005 to .015 inches.

Regardless of the brass you are using new or used all the cases should be measure with an accurate dial caliper.

Then again I could be just blowing smoke up your rear-end……………….

This is a kind of old post but here go's. For some reason the fact that the origional post was talking of a hand gun cartridge in an autoloader. That being the case, I'm not sure how it could be neck sized, it's a straight wall case. Next would be the 1/2 load theory, valid in a reduced load in a rifle cartridge using slow powder but not in the pistol with one exception. If one was 1/2 loaded, the report would have been light, obviously so. If that happened, the bullet may have stuck in the barrel and a full load behind it would rupture the barrel.

I have heard of this thing happening in auto loader's and my understanding is it's caused by an unsupported head in the chamber. Not really sure how that work's, but then I only own one autoloading centerfire and I don't load for it.. My guess is that they have some slop in the chamber to facilatate loading and unloading the round. If that slop is to great, boom! Take a revolver with a hot load that will allow you to open the cylinder and you'll find the cases are a bit sticky coming out. The cartridge's in both cases are headspaced on the rim but the autoloader's case head is unsupported, the revolver's is tighter.

Actually Don this can and does happen. If the shooter isn't pay close attention they won't even notice that it happened until.....BANG the gun blows up. But, if that were the case the barrel failure should have occured beyond the chamber. My guess is that one of two things happened.

1 the cases stretched from repeated loading and was noticed thus causing headspace issues. Or 2. the press threw a double charge into the case. I use a dillon progressive press myself and have had a double charge myself. Luckily My load are way down on the scale. I only attempt to reach a velocity high enough to make major classification at the local shoots. Even so the double load really rocked my world.My gun didn't fail, still i was glad that my hand was still attached. Talk about ruining a good day at the range.

That's interesting. I'm not sure how you could double charge unless the charge got hung in the drop tube. In the origional post, it was the barrel that burst in a .40 auto. The barrel cracked from the back of the chambergoing forward about the length of the round. Huh? It's possible that there may have been a partial charge thrown in one case, and a full charge plus in the next. Something is wrong here as the uncharged case hasn't be mentioned. Maybe it hasn't been fired or perhaps it had enough to make the bullet exit the barrel while overloading the next case? I have seen light charges stick bullets in barrel's and I can imagine a full charge not droping, seen that to. I'm not a big auto fan but I understand the unsupported head can cause problems with handloads.

The headspace might do it but then it could be as another suggested, a to long case that got into the forcing cone and pinched the bullet running pressure up. I've seen that in a rifle when I tried to get one more round. Doesn't pay!