Base of brass seems to be slicing?

[CA_Shooter]

For my Bolt action rifle:

i have a new barrel and for about the first 5 or 6 shots there were some tiny nicks on the bottom of my brass (on the Hornady name label). After that I noticed there were no longer nicks. It looked like it was swiped a bit. Then after about 20 or so shots I no longer noticed anything.

Anybody know what this is coming from? Dangerous?

EDIT: looks to be case head swipe

 

[243winxb]

After the chamber is dry, it may stop.

Ejector hole mark?
Brass flow into the ejector hole can be a sign of high pressure.. The right brass shows light flow.. This can be seen on some factory fired brass.. Showing higher pressure moving to the left. Until the pocket expanded and primer fell out.

 

[CA_Shooter]

After the chamber is dry, it may stop.

Ejector hole mark?
Brass flow into the ejector hole can be a sign of high pressure.. The right brass shows light flow.. This can be seen on some factory fired brass.. Showing higher pressure moving to the left. Until the pocket expanded and primer fell out.
View attachment 1204631

Maybe it was a lube thing. I did put a lot of lube for the first set of shots out of the barrel.

It was probably in between the picture in the very right and the one next to it. Interestingly, I went to look at my cleaned and resized brass and I can’t find them anymore. Looked at all of them too so it was probably a really light nick. It was factory Hornady SST (used 20 of them for break in)

 

[Mad_Charlie]

I have made it a habit to make sure my chamber is dry and free of oil before any shooting session.

 

[divingin]

Feeding from a magazine? Rims and case bodies can get nicked and scratched from sharp edges on the feed lips.

Oiled up where parts move is OK; but keep oil and grease out of the trigger group and the chamber and barrel. Trigger because you don't want it slipping and misfiring, barrel because you can get hydraulically bulge it, and chamber because you'll get weird pressure signs at normal pressures.

 

[CA_Shooter]

Feeding from a magazine? Rims and case bodies can get nicked and scratched from sharp edges on the feed lips.

Oiled up where parts move is OK; but keep oil and grease out of the trigger group and the chamber and barrel. Trigger because you don't want it slipping and misfiring, barrel because you can get hydraulically bulge it, and chamber because you'll get weird pressure signs at normal pressures.

Yes it did feed from a magazine. Never had this issue before from thousands of rounds (that I noticed).

This was definitely the most lube I’ve used when firing though because I figured since it was a new barrel to use extra lube. Looks like that was not a good idea.

What is hydraulically bulging it?

 

[M-61]

This was definitely the most lube I’ve used when firing though because I figured since it was a new barrel to use extra lube.

Not sure where this 'extra lube' is going. If it's in the camber or on the case it shouldn't be. They should be clean and dry.
An example would be the Brit's when they proofed their 303 Lee Enfields. 1st round is normal load. If it passes it goes to step 2. That's a double load of powder.
If it makes it through that they go to step 3 They then oil (lube) the case. That is the ultimate test for strength.

 

[CA_Shooter]

Not sure where this 'extra lube' is going. If it's in the camber or on the case it shouldn't be. They should be clean and dry.
An example would be the Brit's when they proofed their 303 Lee Enfields. 1st round is normal load. If it passes it goes to step 2. That's a double load of powder.
If it makes it through that they go to step 3 They then oil (lube) the case. That is the ultimate test for strength.

Used CLP in the chamber, lugs, and barrel

 

[Uncle Ed]

A lubed cartridge case can not grip the chamber walls and it can increase bolt thrust up to twice the amount.

The extractor marks and swipes you see is because the chamber pressure exceeded the elastic limits of the brass. Meaning the high chamber pressure forced the brass to extrude into the extractor hole in the bolt face.

With a dry chamber and cartridge, the case body grips the chamber walls when fired. Then the base of the case must stretch to contact the bolt face. This stretching action of the brass makes the case act like a cars shock absorber. This reduces the amount of bolt thrust and the dwell time the base of the case is contacting the bolt face.

Below is from the 1929 British "Text Book of Small Arms" the British used the base crusher system of measuring chamber pressure. The copper crusher was placed on the base of the case and a oiled cartridge must be used to measure actual chamber pressure. Two oiled proof pressure cartridges were fired during proofing and if the headspace increased .003 or more the rifle failed proof testing.

My guess is the new barrel caused a higher pressure until a few rounds were fired. The only way oil or grease on a cartridge can increase chamber pressure is if it is squeezed forward of the bullet when the case is expanding. This same oil or grease can prevent the case from fully expanding and decrease the case capacity increasing chamber pressure.

 

[CA_Shooter]

A lubed cartridge case can not grip the chamber walls and it can increase bolt thrust up to twice the amount.

The extractor marks and swipes you see is because the chamber pressure exceeded the elastic limits of the brass. Meaning the high chamber pressure forced the brass to extrude into the extractor hole in the bolt face.

With a dry chamber and cartridge, the case body grips the chamber walls when fired. Then the base of the case must stretch to contact the bolt face. This stretching action of the brass makes the case act like a cars shock absorber. This reduces the amount of bolt thrust and the dwell time the base of the case is contacting the bolt face.

Below is from the 1929 British "Text Book of Small Arms" the British used the base crusher system of measuring chamber pressure. The copper crusher was placed on the base of the case and a oiled cartridge must be used to measure actual chamber pressure. Two oiled proof pressure cartridges were fired during proofing and if the headspace increased .003 or more the rifle failed proof testing.

My guess is the new barrel caused a higher pressure until a few rounds were fired. The only way oil or grease on a cartridge can increase chamber pressure is if it is squeezed forward of the bullet when the case is expanding. This same oil or grease can prevent the case from fully expanding and decrease the case capacity increasing chamber pressure.

Thanks for the very detailed reply. Sounds like I really screwed the pooch! Thinking back I actually squeezed CLP onto the lugs and chamber from the CLP bottle.

Going forward I’ll make sure it’s dry prior to firing!

Could this have messed up my action or barrel in a permanent way and if so how would I know?

 

[Uncle Ed]

If you look at a SAAMI cartridge and chamber drawing the average cartridge has the headspace listed as min and max with .010 between the two. And just because the bolt closes on a NO-GO gauge does not mean you have excessive headspace. This leaves about .007 more headspace wear before the rifle fails a FIELD gauge.

The more bolt thrust you have the faster the headspace will increase over time. As an example, my fired 30-30 cases always have the primers protruding from the base of the case. This is because the chamber at 42,000 psi is not great enough to push the base of the case back into the bolt face. You can also see this when you make a workup load starting at the suggested start load. The primers will protrude until the chamber pressure forces the base of the case against the bolt face.

 

[divingin]

What is hydraulically bulging it?

Oil and grease (like most liquids) are largely non-compressible. If they are in the barrel as the bullet is launched, it can either be pushed along by the bullet and exit out the muzzle, or the bullet can ride over it. If the bullet rides over the oil or grease, the barrel wall gets pushed outward, potentially causing a bulge at that point.

 

[CA_Shooter]

Oil and grease (like most liquids) are largely non-compressible. If they are in the barrel as the bullet is launched, it can either be pushed along by the bullet and exit out the muzzle, or the bullet can ride over it. If the bullet rides over the oil or grease, the barrel wall gets pushed outward, potentially causing a bulge at that point.

Ouch hopefully I didn’t kill my barrel. It’s a Krieger- do you think I could have trashed it?

 

[Dub]

Ouch hopefully I didn’t kill my barrel. It’s a Krieger- do you think I could have trashed it?

they are not easy to trash. Just make sure not to do more of it!

 

[CA_Shooter]

Here are images of two Hornady brass casings fired from my rifle. You’ll notice the rim of the one on the right is curved downward. I found about 19 cases like this, which I assume was from my first box of SST factory rounds. I’ve shot both brass twice now. I noticed I have some factory unused SST rounds that also have the rims slightly curved too

The brass rim on the left is normal.

Did I possibly get a bad batch?

 

[divingin]

Ouch hopefully I didn’t kill my barrel. It’s a Krieger- do you think I could have trashed it?

A tight patch on a jag will indicate if that happened. You'll feel a repeatable free-running spot as you push it through.

 

[Metal God]

That is brass flow for sure and some you can even see the extractor grove as well . The one thing that's interesting to me is I've never seen so much brass flow into the ejector that didn't at least have pretty flat primers if not cratered primers but those primers look great .