Strange dents in fired cases???????

[jerrschmitt]

Went to the range yesterday and was shooting some .243 Ackley reloads out of my Remington 700. 42/R15, 55 Nosler BT, CCI 200 primers in FC cases. Cases were on their 3rd reload. When I got home I noticed that two of the 40 rounds I had fired, had strange dents in them. They were located in the middle of the box so I assume they were not the last rounds fired, nor the first. I could not see anything in the chamber and didn't notice any wild fliers in any of the groups I shot. Any ideas as to what may have caused this?

 

[bheadboy]

strange, but i have had this one time a long time ago, with a 219 mashburn zipper in the 2nd or third firing i think, i belived the conclusion then was bad ignition, slow pressure build up leaking around the neck back to the case body.

in my case i thought i had possible gotten lub on finger and primer, or had a couple of bad primers to begin with, also thought as i had cleaned the cases that cob particle may have blocked the flash hole and reduced the ignition,

What ever it was a slow ignition that caused the dents

Bob

 

[nfhjr62]

Very likely case lube

 

[dennisinaz]

I have seen that once before as well. It was a worn out barrel, over generous neck which somehow caused the gas to go back around the neck and collapse the case . The shoulder is rigid enough that it does it right below it. Case lube has nothing to do with it. Case lube will cause very small dents IN the reloading die.

I have not been able to duplicate it as I pulled the barrel off that did it. As an aside, I was getting velocities about 1000 fps less than the manual suggested when this happened to me.

 

[bozo699]

There was a topic on here maybe 6 moths ago or so with the exact same problem, I am pretty sure it was resolved but can't remember the exact outcome so I don't want to say but I will try to do a search later to find it, the case's were identical to yours I remember that much for sure and that it was discussed on this forum.
Wayne.

 

[gmorganal]

I have had this one time in my 40 years of reloading, and it was with starter loads in a 7mm UltraMag. In other words, my beginning loads were too low on pressure and didn't seal the chamber by blowing the brass up against the inside of the chamber, thereby allowing gas to pass back into the chamber between the brass and chamber and denting the brass in. I chunked the brass and subsequent, higher powder charges sealed better and better. As you know, the 7mm UltraMag is one of the larger overbore cartridges ever factory produced, and it didn't take long to go from not sealing the case to having ejector marks on the case head. I refer to this as a spikey cartridge, one that goes from low to high pressure in just a small percentage of the case capacity. The 243 Ackley isn't quite as overbore as the 7MM Ultra, but it is a tad on the overbore side of things.

 

[jerrschmitt]

It's not from case lube. I use Imperial wax and I remove it after sizing. It has to be pressure on the outside of the case, but I can't figure out how it got there. The load is mid range for this cartridge.

It's got me mystified.

 

[gmorganal]

Were the charges weighed or just thrown? If they were thrown, a bridge of powder could have caused a lighter charge than intended.

 

[jerrschmitt]

Were the charges weighed or just thrown? If they were thrown, a bridge of powder could have caused a lighter charge than intended.

These were thrown. You may be on to something.

I fired eight groups of five rounds. All were pretty close to the same size. That makes me think it has to be something else.

 

[Silverfox]

gmorganal has the correct response. I had similar dents in some of my casings and it was because the case wasn't expanding fast enough to prevent gas from getting back past the neck and shoulder areas and down into the casing wall area. The powder charge was too light. The dents in my casings weren't all quite as deep as those pictured in the opening post, but bad enough. These were WW .204 Ruger casings and the powder I was using was Reloder 10X from a new lot of powder I had purchased. The new lot of powder had a way slower burn rate that the first lot I had used successfully.

 

[gambleone]

I also agree with gmorganal. I've seen this before being caused by too light a charge & gas getting back behind the neck. Only the 2nd time I ever heard of it.

 

[TheSnake]

This is interesting. I have some cases where the burnt or soot is around the outside of the neck and onto the shoulder and these were lite loads at the starting of load development. Is this the same thing but not as bad?

 

[necchi]

Is this the same thing but not as bad?

Pretty much, Yup.

 

[Martin52]

Jerschmitt,

If the cases were annealed with a little too much heat this may have contributed to the dents in the case body.

Martin

 

[jerrschmitt]

I also agree with gmorganal. I've seen this before being caused by too light a charge & gas getting back behind the neck. Only the 2nd time I ever heard of it.

I think you guys have nailed it. Thanks for all the responses.

 

[people]

That is very interesting. I have never seen anything like that before. Humm learn something new every day.