Why did Casing cave in?
I got my cuz some hand loaded (not custom loaded to this gun but a generic hand load)7mm Ultra Mag 140 Grain Nosler bullets and when he was target shooting, 1 casing was caved in, in 3 spots by the bullet end, after being shot . The shot went extremely flat or extremely high as he was shooting at 400 yards and the bullet hit 2 feet above the target point.
What causes this and is it dangerous? I am guessing it has to do with pulling a vacuum on the casing due to a hot load but I am only guessing.
Mad Dog
What causes this and is it dangerous? I am guessing it has to do with pulling a vacuum on the casing due to a hot load but I am only guessing.
Mad Dog
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My guess is oil or dirt in the chamber that collected at the case shoulder. Clean the chamber scrupulously especially in the shoulder and neck areas. 0 -
Sounds like an overload of powder.
If you don't care where you are going, you can't get lost.0 -
Travis, if by 'caved in' you mean the case had indents, the most likely explanation is some contamination as v35 suggested. But I must admit I don't understand how this would affect the ballistics so noticeably. An excessive charge of powder typically causes splits / cracks in the brass. If you still have the case, look at the base, the primer and the primer pocket - are there signs of excess pressure such as bolt marks, pierced primer cup, extraordinary flowage of the primer cup around the firing pin mark, anything like that? If it were excessive pressure, almost certainly you would see some or all of these indications. You need to compare that to fired factory loads, BTW, as some rifles / cartridges will demonstrate such signs at normal pressures.
Are you certain these indents (if that's what they are) were not there before shooting? An excess of lube on the case, especially in the neck and shoulder areas, will produce dents in the case in the resizing process.
I don't think I'd buy any more ammo from that source, merely as a matter of principle. When it comes to high power rifle ammo, either get it from the factory, a known custom loader or make your own. Far too easy to have Bubba screw up - my $0.02 on that matter.0 -
I've seen cases dented at the shoulder/neck by an underpressure load which failed to force the neck against the chamber. I;ve never seen lube dents from resizing remain after a full pressure firing.
Mobuck0 -
I also thought,at first,lube dents.But as Mobuck said,they would dissapear upon fireing.I have never seen this condition on a fired case.will be interested to hear opinion of others. 0 -
They were indentations on the necked down portion of the shell. I did not notice cracking or any sign of stress like it wanted to explode but it looked like it tried to implode which is why I suspected it pulled a vacuum type seal when shot (if that is possible). The shells were mint as these were not reloads but a custom load through Quality Cartridge. I have purchsed 175 grain 338 Win Mag loads through him before and was pleased, so this is a first. We had just shot factory Remington 140 grain noslers and he did have 1 of those misfire (not fire) but we cleaned the barrel pretty good and had fired less than 9 rounds through it. Also the dents were BIG dents, very intimidating after having shot it, which is why I asked if it was dangerous.
Mad Dog0 -
Better description is as follows. Three dents going left to right, Left dent is small (1/8" wide by 1/4" long and shallow) and almost touches the neck. Middle dent is medium (3/16" wide by 1/2" long and 1/8" deep) and does touch the neck. Right dent is big (5/16" wide by 11/16" long and 3/16" deep) and crosses the neck by 1/8" and you can see it when you look in the casings bullet cavity.
The base looks fine with a perfect center fire indention. Hope this helps and thanks for any info.
Mad Dog0 -
Better description is as follows. Three dents going left to right, Left dent is small (1/8" wide by 1/4" long and shallow) and almost touches the neck. Middle dent is medium (3/16" wide by 1/2" long and 1/8" deep) and does touch the neck. Right dent is big (5/16" wide by 11/16" long and 3/16" deep) and crosses the neck by 1/8" and you can see it when you look in the casings bullet cavity.
The base looks fine with a perfect center fire indention. Hope this helps and thanks for any info.
Mad Dog0 -
I've seen it many times. It was not sized correctly. I'll bet when the bolt closed on that case, it was tight. The neck hit too soon and when it does, it gives either a three or four dent look to the first taper.
The NRA is on our side!0 -
Having fire-formed many a wildcat case from another case, no "wrinkle" in the brass caused by bolt closing on a too-long crumpled case will remain after firing. The pressure inside a case at firing is tens of thousands of pounds per square inch and such great pressure will not allow a dent to remain in the relatively soft brass case after firing. Such pressure will cause the case to conform to the chamber shape, hence my wildcat cases after fire-forming take the new chamber shape exactly, and the old case shoulder and neck take the form of the new chamber.
Any contamination in the chamber or on the case would become embeded in the soft brass case at firing, and would still be there after firing. What kind of contamination could be so large as to cause the dents described, and still allow the case to chamber and extract without notice?
I believe what may be happening, and I am only guessing based on something I think I read somewhere long ago, is that the load is too light to exert enough pressure to cause the neck to seal tightly to the chamber wall, and gas is flowing back around the neck when pressures are the highest in the bore, and causing the rounded denhts (not sharp, like creases would be) described. Again guessing, the description of the bullet flight suggests the case may somehow have received perhaps a .277" bullet instead of a .284" bullet, which might cause the erratic bullet flight described. A small bullet could also prevent tbe neck from sealing against the chamber wall and allow gas to flow back and dent the case. Maybe the cases were accidently neck-sized for .277" bullets instead of .284" bullets.
It could be dangerous if the gas gets around the case and out of the chamber.
That is my speculation. Next.0 -
while i have never had this happen i think mobuck and JudgeColt has the right theory as what happened.
doc0 -
I believe Mobuck and JudgeColt have hit it on the head. I've had this happen with comparatively low loads. Shoulder dents will also happen with cases that have been sized many times without annealing the neck(and moderate loads).
If you shoot a load, in the same group, that is high or low in powder charge(compared to the norm) the impact can be high OR low. This is due to different barrel time and barrel vibration. When you "catch" the top or bottom of the vibration arc the barrel is dead stopped. Anywhere else and the barrel is moving(hopefully vertically). You can have a high impact with a low load if the barrel is in the "up" mode of it's vibration travel. Hope this is clearer than mud.
Bud
Bud Pitt0 -
Send the case to the manufacturer.
Undersized bullets will always cause the bullet to fall short, wayyy short.
Clouder..0
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