Brass Shoulder "pimples" - Page 2

Homes Outside · #31 03-17-2017, 11:02 PM

OK. Finally got some decent pictures. It's pretty difficult to get a camera properly focused on such a small detail.

To answer some questions
This is the only shell that has this deformity. All of the cases were neck sized only.
I shot this so long ago I can't remember if there was anything special about if as far as extra bang or flier shot etc.
Think I'll just fire off the primer. This being my first set of reloads and all.

First photo is pretty easy to see two bumps right in the middle of the shoulder

Second image is a different angle but you can make out the pimple in profile on right edge

I have a couple other pictures but they don't really show much of anything different

Any guesses ?

Edit add one more picture

BuckCuller · #32 03-17-2017, 11:27 PM

I have no idea but if I took a very long shot guess at it maybe the crimp was a little short on that one or the neck to long which bulged the shoulder of the case a bit. Then when fired reformed the case to the chamber but not completely and left some dimples on the shoulder.
If it was the chamber all of your shot brass would look like that.
Second outlandish guess is if a piece of primer, stainless tumbler media or something was in the shell and positioned between a boat tail bullet and the case and your brass is not fully forming to the chamber it could maybe do that.
I'm all guessed out.

260 Rem · #33 03-18-2017, 08:19 AM

Definitely looks like something was inside the brass and jammed up on the way out...if you have noticed accuracy degrade, and if you have access to a bore scope, would be a good idea to check the bore. Similar to the scenario my friend experienced as described in post #16 ...except something that happened at the factory resulting in debris mixed in the powder. As long as it did not score the bore, the problem is long gone.
Buck is correct, If it was a pit in the chamber, it should occur consistently.

bubba300 · #34 03-18-2017, 09:17 AM

Like others have said something had to be inside case when it was fired.
Or maybe someone was monkeying around with it(young boys like to play with stuff like that).
What make of case is it.
I'll take a guess at Winchester.I have had some of there crappy stuff .
I would try to cut it in half and see what it looks like from the inside.

Homes Outside · #35 03-18-2017, 09:25 AM

Well no kids in my house so that's ruled out. It's actually a Hornady case too. Cutting it in half is an idea. Maybe I'll try that.

tchardy1972 · #36 03-18-2017, 11:00 AM

My vote goes for rust pits in the chamber.

fps plus · #37 03-18-2017, 03:36 PM

It must be a pit in the chamber if all the brass fires have the same marks

trophybook · #38 03-18-2017, 03:44 PM

X3 for chamber pits

pikergolf · #39 03-18-2017, 03:56 PM

Quote:

Originally Posted by tchardy1972

My vote goes for rust pits in the chamber.

My vote as well, it's been fire formed, I can't see there being any other cause. Anything else would come out when it was fire formed in the chamber.

densa44 · #40 03-18-2017, 04:17 PM

It looks to me like what ever was in the case was one piece that made both dimples and the crease that joins the dimples. My guess one of those SS rods rich re-loaders use to polish their brass.

elkhunter11 · #41 03-18-2017, 04:46 PM

Quote:

Originally Posted by pikergolf

My vote as well, it's been fire formed, I can't see there being any other cause. Anything else would come out when it was fire formed in the chamber.

In that is the situation, every case should have the same marks on it.

260 Rem · #42 03-18-2017, 05:20 PM

OP indicated this was a factory round...only one of ten had protrusion dimples. Logic suggests that a chamber pit would result in the creation of a dimple at the same spot every time. OP said there were seven dimples...did not say similar dimples occurred on any of the other nine cases he resized. The dimple may not get ironed out against the chamber with generous headspace, and it would likely have occurred when the base was jammed against the bolt face.
Repeating my friends experience ... his decap pin pulled out and stuck in the flash hole un-noticed when he primed and loaded the round. As bad luck would have it, it was the last case he resized in that lot so it went un-noticed. After he fired the round, he noticed accuracy fall off immediately and did a borescpoe inspection which revealed a score mark in the bore a couple of inches before the muzzle. When he inspected his die, he discovered the missing decap pin and deduced the bore score was caused by the very hard pin catching in the rifling or perhaps tumbling in the bore. This seems to make sense.
Given that experience, I believe it is possible that if some debris got mixed in with the factory loaded round...some of that debis could have hit the shoulder on the way out (the shoulder is the logical place for it to show up). As long as the debris did not get caught in the grooves or tumble if it was pin shaped, the bore should be OK....but worth a check. I would look very closely at the lead as well. I don't know how brass is formed but I think the flash holes are punched. Maybe a piece of the punch broke off?

pikergolf · #43 03-18-2017, 05:25 PM

Quote:

Originally Posted by elkhunter11

In that is the situation, every case should have the same marks on it.

Maybe some of the loads are a little hotter? I just can't see the marks coming from within as the brass is being pushed against the chamber.

Smokinyotes · #44 03-18-2017, 05:29 PM

Is it possible the brass was tumbled with stainless steel pins and a couple pins were left in the case?

tchardy1972 · #45 03-18-2017, 09:22 PM

Quote:

Originally Posted by pikergolf

Maybe some of the loads are a little hotter? I just can't see the marks coming from within as the brass is being pushed against the chamber.

I completely agree. Could even be that some of the brass is softer than others or like you said some my be hotter. Pretty hard to dent the case from the inside when it's against the chamber.

58thecat · #46 03-20-2017, 09:09 AM

Quote:

Originally Posted by Dean2

Over 50 years I have done thousands that way and never set one off. I even re-used the primers with no problems. Even if you did set one off the die is sealed at the top and would contain the discharge. Its a primer, not a grenade!

Me too

Mike_W · #47 03-20-2017, 09:31 AM

This is weird for sure. So just to recap this is your first time reloading? You resized the die and seated a primer before you noticed the pimples? This was a Hornady factory ammo once fired brass? This is only on one of the 10 pieces of resized brass?

What was your procedure for resizing?

There is nothing that makes sense really. If it was shot out of the same gun and there was a chamber issue it should be on more than one piece.
If it was resized proper the "pimples" should have been pushed back in.
I have never seen a lubed shoulder create "pimples" before only indents.

I think I will need to say this is something with a resizing die but the only thing that would make even the slightest sense is a lube build up with air voids.

Nyksta · #48 03-20-2017, 09:55 AM

I would set it aside out of commission and see if you ever see this result again on other cases. If you continue shooting and resizing and it never happens again then I wouldnt worry about your gun or your equipment.

One other thing could be a seized up neck crimp that as your die came down onto the casing, it caught on the neck and instead of the case going into the die, the die pushed the neck down and the shoulder had a twisting or crushing pressure which caused the beginning of multiple folds with high points and low points. Like when you start to crush a popcan with the random weak spots that give.

Full sizing your brass is another option depending on your intended use of shooting. The speed of loading and conditions in the field would benefit from easy loading. Neck sizing tends to get very snug loads that dont always load or unload from the chamber as fast as you might want. If your just bench shooting it doesnt matter as much.