I'm stumped...what is it ?

[watkibe]

This case got dented like this when it was fired. It was the first cartridge fired in my new Handi 243 barrel.
1- It couldn't have been something in the chamber, the round chambered fine and the action closed.
2. The closest thing I've seen is when you get too much lube on a case before sizing it.
3. I swabbed the chamber immediately after - no sign of grease or oil.
4- I inspected the chamber with a flashlight, it looked fine.
I broke down the rest of the cartridges and weighed the powder - A-OK there. I reloaded them with one grain less powder. The first one I fired with lots of protective gear and space between the action and my body, into my backstop. It looked normal. I fired the last 2 rounds normally, they joined the group started on the target by the first (dented) round, and no more dents. For these 3 rounds, the side lever action release was a little hard to push.
I used the starting load of H4350 from Hodgdons 2012 magazine data book, new WW brass, CCI LR primers, and Sierra's 100 gr Pro Hunter bullet. The primers were a bit flattened, but no cratering was apparent.
I'm gonna be nervous about shooting this until I get some idea why the case dented. Any ideas, please ?

[wtroger]

That is a gas flow dent. I have seen this once before. For some reason the neck didn't seal and gas flowed back. Usually you see something like this with very light loads. If the chamber looks good and it hasn't done it again you are probably good to go. If you are leery of it have a smith use a bore scope on it and see for sure if the chamber is good

[trotterlg]

Yep, that is what it is, I have seen 303 cases that are near flat.  Larry

[watkibe]

to trotterlg and wtroger:
THANK YOU ! That is something that I had never heard of, so I never considered it as a cause; but it does a very good job of explaining the phenomena in a believable way. And two of you agree, hey, it must be true !
THANK YOU AGAIN !

[bikerbeans]

Oh boy, I've got a box full of 60% loaded H4895 loads for my wife's 243 SL.  Is it maybe a bit undersized bullet or thin neck?
 
BB

[moorepower]

I don't think you will see an issue with H4895.

[jackddavis]

I've never encountered this before, but have heard that it can happen with light loads. It wouldn't concern me unless it happens again with loads that are believed to be normal. Then I'd start lookiing for a reason. Something could be wrong in the chamber. Scratches or gouges that keep the case from sealing well. ? For peace of mind a chamber examination under a bright light or perhaps a chamber cast?

[watkibe]

@bikerbeans: H4895 was chosen specifically by Hodgdon as the slowest powder to ignite properly for reduced loads, 60% as you say. I have used them in other guns without problems.
@jackdavis: The closest I have seen is low pressure 38 level loads in 357 mag cases using Unique, but the cases never dented, just got really smoky looking from the neck not sealing the chamber(probably not denting because they were mostly fired in revolvers and the b/c gap bled off most of the gas leak). I examined the 243 chamber under a strong light, and could see no defect. If it happens again, a chamber cast or a visit to a smith will be in order.

[bigvarmnt]

I'd never heard of this before either with a fired round. Good to know.


I just made a couple that looked like it when I sized some 22 hornet brass


They are vibrating now and I'll shoot the dents out hopefully tomorrow


That dent looks pretty deep, will it re chamber and lock up. Guess it would.


Do you have a whole lot of play when you put a bullet back in the mouth?

[watkibe]

@bigvarmint:
I am sure the dented case would re-chamber and lock up. I'm so cheap I even considered loading it lightly and trying to blow the dent out so I can keep using the case. Despite reloading being a place where I save tons of money, being CHEAP is stupid when safety is in the equation. That dent is now a weak spot in the brass, just waiting for a chance to rupture and spill hot gas in my face. That case will sit on the top shelf of my reloading bench, along with the rest of my special reloading mistakes, as a reminder of what can happen; and to remember that if anything looks, sounds, or acts funny when it comes to loading and shooting, STOP IMMEDIATELY AND FIGURE OUT WHY !!!
Goo question about whether a bullet will seat. If I remember I may try to finger-seat a bullet back in the case, it might tell me something interesting. If I do and it does, I will pass it on right back here !

[bigvarmnt]

I was just curious if it fit back in the chamber, sometimes after you get them out when there is a problem they don't seem to fit back in so good.


I have a 223 that must have a neck/throat area that's bigger than others. When I put a new bullet in after firing and before sizing it is quite sloppy. More so than others.


I've never seen this before and am glad you posted and others have seen it before.

[gcrank1]

If you reuse cases like that you wont get too many reloads before they split there, and they will. All part of the cost of reloading........they will look good on the 'look at this' shelf though.

[Sourdough]

I loaded some reduced loads with my 308 many years ago.  At first the cases were real smoky around the neck.  Then the neck started caving in like that just not that bad.  Switched to military brass and problem went away.  Military brass is thicker and produces higher pressure with same load.