.223 Lapua brass fired in a Winchester model 70 heavy varmint rifle has a small dent (.060" diameter .005" deep) about 1/8" below the shoulder. Does anyone have any idea(s) why?

Just a guess but the case could have doubled back and hit the receiver as you ejected it. Was it a one time thing or does it happen with all/most/any other of the brass?

This sometimes happens when I used too much spray on case lube when full length sizing. However, the small dent disappears, as expected, after firing.

If your 223 is fired in a semi-auto, then it could just be ejection impact on the receiver.

Was it a full charge load? I know with large calibers, sometimes shooting a reduced charge load will result in a similar experience.

I have had unburned granules of powder in the chamber produce small dents in fired cases.

Powder grains or hits on the case deflector bump upon ejection; in any case, do not lose sleep over it.

Thanks for the response guys. The dent appeared AFTER firing and today at the range mysteriously went away half way through the session. I'm stumped.

And a further note, the dent appeared in exactly the same place every time before it disappeared. Go figure.

Seems you had a chunk of something in the chamber that was leaving a dent upon firing, chunk must have fallen out and like magic you fixed it.

I do believe you have it Snellstrom. Actually it is my shooting buddy's gun and reloads and I've already accused him of sloppy gun cleaning :-). Thanks again. Mike

Mud dauber nest, happens all the time.

Now that it is gone, don't worry about it.

If you have cases with work hardened necks (fired several times)and some low pressure loads the problem may be the necks are not sealing the pressure between the case neck and the chamber wall. This allows a little gas to get by and it will usually create dimples just back of the shoulder. Annealling the necks and or increasing the powder charge 1 or 2 grs will solve your problem.
If you can lay hands on an older Speer manual (Speer # 10) on P-58 & 59 they talk about shoulder collapse and show some pictures of it on P-59. Hope that helps

Whenever I am fire forming my 223AI I get those dents at the first of the range session. Real weird. They disappear after the first 20or so and start to form perfect AI cases after that. On the subsequent firings of the dented cases the dents go away. Have not been able to figure this one out.

Cold chamber vs hot chamber???

Completely stumped. Thanks for the thoughts, guys.

Have you trimmed your cases to length? If not then the excess brass has to go somewhere.. Also make sure there is no excess oil on the cases or in the chamber. Also inspect the fired cases real well and make sure there are not any small cracks at the dent.

quote:

Originally posted by snowman:
If you have cases with work hardened necks (fired several times)and some low pressure loads the problem may be the necks are not sealing the pressure between the case neck and the chamber wall. This allows a little gas to get by and it will usually create dimples just back of the shoulder. Annealling the necks and or increasing the powder charge 1 or 2 grs will solve your problem.
If you can lay hands on an older Speer manual (Speer # 10) on P-58 & 59 they talk about shoulder collapse and show some pictures of it on P-59. Hope that helps

^^^^ This

quote:

Completely stumped. Thanks for the thoughts, guys.

I don't think you have to be.

This "strange" issue has occured to me on occaision and it has always been debris in the chamber.

Like wasbeeman says; I've got a 25-06 Remington in a Blaser R93 which puts a minor dent/ridge in the case below the shoulder due to the magazine bolt stop when it is ejected from the chamber (the case strikes the barrel opening).

Usually after a tough hunt, a small piece of debris in the chamber, I've encountered a pine needle, a piece of grit, unburned powder particle, etc. After noticing such on a case, I check the chamber and always find the offending particle.

quote:

The dent appeared AFTER firing and today at the range mysteriously went away half way through the session. I'm stumped.

Yes, the issue resolved itself most likely because the particle eventually stuck to the wall of a case and was ejected with it. Do check the cases though, since you may damage/scar a reloading die if the offending bit is still stuck to the case (probably dropped off).

I wouldn't loose too much sleep now since the issue has dissapeared.

quote:

Originally posted by woods:

quote:

Originally posted by snowman:
If you have cases with work hardened necks (fired several times)and some low pressure loads the problem may be the necks are not sealing the pressure between the case neck and the chamber wall. This allows a little gas to get by and it will usually create dimples just back of the shoulder. Annealling the necks and or increasing the powder charge 1 or 2 grs will solve your problem.
If you can lay hands on an older Speer manual (Speer # 10) on P-58 & 59 they talk about shoulder collapse and show some pictures of it on P-59. Hope that helps

^^^^ This

Mine was brand new Lapua brass. I will have to check but I think I was running them pretty hot. Don't quote me but I thought I was at 25 grains of Varget with a 77 SMK.

quote:

Originally posted by McKay:

quote:

Originally posted by woods:

quote:

Originally posted by snowman:
If you have cases with work hardened necks (fired several times)and some low pressure loads the problem may be the necks are not sealing the pressure between the case neck and the chamber wall. This allows a little gas to get by and it will usually create dimples just back of the shoulder. Annealling the necks and or increasing the powder charge 1 or 2 grs will solve your problem.
If you can lay hands on an older Speer manual (Speer # 10) on P-58 & 59 they talk about shoulder collapse and show some pictures of it on P-59. Hope that helps

^^^^ This

Mine was brand new Lapua brass. I will have to check but I think I was running them pretty hot. Don't quote me but I thought I was at 25 grains of Varget with a 77 SMK.

You don't have to sit at the bench and fireform,
go out and kill something!

Stepchild

quote:

Actually it is my shooting buddy's gun and reloads and I've already accused him of sloppy gun cleaning

Steeeeeeeeerike three.