What do you figure caused this case neck crease

[JDHasty]

I haven't the foggiest idea. Just asking out of curiosity. Not my circus and ain't my monkey.

https://hunting-washington.com/smf/index.php/topic,283566.msg3858446/topicseen.html#new

[MostlyLeverGuns]

I would guess gas dimpling from low pressure not expanding the case neck enough to seal the chamber. I have had such shoulder dents on several different rifle calibers when loaded very light, case is sooty after firing.

[Dusty Bannister]

Not knowing the sequence of events, it could also be a lube dent from sizing the case that went unnoticed until after the round is loaded. I can not imagine anyone foolish enough to intentionally load a case showing that severe of a dent in the side of the case at the shoulder.

Perhaps excess lube on the bullet being displaced upon firing?

[Winger Ed.]

I'm going with a excess lube that caused the dent.
In the early days, I had that happen with a few .270s.

[M-Tecs]

"When I shoot it, the brass comes out with a dimple near the neck. The photo below shows it (I have reloaded the brass, but this case has been fired once already.)

The dimple does not show up if you cycle ammo thru the chamber without firing. It only shows after firing.

In my mind, it looks a lot like the hydraulic dimples you get reloading when you have excess lube on the brass when runs thru the resizing die".

[stubshaft]

Gotta go with low pressure too.

[TNsailorman]

I have seen that in resizing brass occasionally and it only occurred when the brass in question had too thick of brass in the shoulder section. When squeezed it has to go somewhere. I have never seen it do that on firing and that puzzles me a little. Just thinking out loud here a little with these questions that only he can answer. 1. Did he form the cases from a longer, larger case that set the shoulder and neck back into the case where it is thicker? 2. If so, did he properly thin the neck back to the thickness it should be on that caliber of case (neck turn or ream)? 3. If he did not, he is running the risk of highly elevated chamber pressures as the bullet could be forming a very tight seal in the case, sort of like a super hard crimp. I would very much like to see a case just after it is fired and before he had cleaned it up. No actual experience with this particular problem but calling 60 plus years of reloading experience of similar problems. I will be very interested in seeing the final answer, if there is one. james

[Bazoo]

I've never seen or heard of pressure dents like that upon firing... that's some crazy stuff.

[BK7saum]

Low pressure dent.

I had some of these in a 2506 improved fireforming load. the bullet was seated out a little with slower powder.

It happens.

[Winger Ed.]

HA!! After reading through the whole thread, it must be something in the chamber.

It threw me off since at a glance, I thought it was a fresh reload.
But the guy said he'd reloaded that one after firing, and that factory rounds did the same thing.

[35 Rem]

Very odd. He says it does it every single shot even with factory loads. I don't see how the dimple could be formed other than from gas flowing between the chamber wall and case. There is no way something could project from the chamber large enough to do that without locking cases in the chamber after firing IF they would even chamber at all. What I don't understand is how gas could leak between case and chamber so consistently even with factory loads. It's almost as if there were a passage that gas is flowing through. A crack maybe. But the gunsmith has examined it with a bore scope and hasn't found anything. I'm trying to imagine if it's possible that the bore could have been sleeved and how that might create a path gas could flow back into the chamber through??

[Texas by God]

I’ve had some dents like that from over lubing 30-06 brass to reform to 7.65 Mauser.
They iron right out on firing.
Dent formed FROM firing?
I can’t see it happening.


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[rockshooter]

I periodically get dents like that when making 25-20 from 32-20. As mentioned, the dents mostly shoot out

Loren

[Bad Ass Wallace]

Looks like a 38/40 shell which are very thin brass in the first place. I used to get similar when forming brass from 44/40 (too much case lube) or else there is a grain of powder stuck inside to the chamber wall.

Mark a round with a texter, load and fire, then see if it occurs in the same place every time.

[Rapier]

Usually I only see this when forming larger cases into smaller calibers and also when so forming, switching from commercial to military brass. The thicker brass has no place to go, so begins to fold inward, creating a dent like that.
Probably coming from firing thicker brass in a chamber, causing the brass to expand with no where to go. Chamber could have been cut with a worn reamer, making the chamber smaller in diameter. Could be checked by turning a new reamer in the chamber, by hand. If correct, it should turn freely with the fingers

[35 Rem]

Usually I only see this when forming larger cases into smaller calibers and also when so forming, switching from commercial to military brass. The thicker brass has no place to go, so begins to fold inward, creating a dent like that.
Probably coming from firing thicker brass in a chamber, causing the brass to expand with no where to go. Chamber could have been cut with a worn reamer, making the chamber smaller in diameter. Could be checked by turning a new reamer in the chamber, by hand. If correct, it should turn freely with the fingers

He says it happens even with factory ammo every time.

[Sam Sackett]

Might want to ask him if he is having any issues when chambering a round. Does it slide in easily or does he need to force it. There may be an issue in the chamber itself. Maybe something stuck in there. Get a borescope and have a look. If that is a thin wall case it wouldn’t take a whole lot of bolt pressure to deform it…..

Or maybe not….
Sam Sackett

[poppy42]

I'm going with a excess lube that caused the dent.
In the early days, I had that happen with a few .270s.
I’m with you Ed! When I was young naïve and didn’t really have a clue what I was doing I had it happen and it drove me nuts trying to figure out what it was from. Fortunately someone much older and wiser than my then 23 years told me and in no uncertain terms” Sunny your using too much case lube” at the time I had a hard time believing that too much grease could cause it to dent! Obviously in 1983 I didn’t know much about hydraulics either lol

[littlejack]

Doesn't really look like a lube dent to me. Years ago, yep, (when I was starting out) I expierienced the lube dent issue. To me it was more of a ripple, and there were usually" more than one around the the shoulder. Don't know what the issue is, but the OP says it only happens when the cartridge is fired. So, it has nothing to do with a case lube issue. If it was soot, there would be soot on the
fired cases. It happens in the same place every shot. IMO,
it is connected to the chamber in some way, as it does the
same thing to factory rounds.