I seriously doubt this is case head separation but what do you guys think?

[Tidus56]

Just my 2 cents, the line in the first picture is from the sizing. It looks like the die might be a bit rough. Did you clean out the die before use and lube the inside of the resize die? I have seen the most growth on the first firing. I guess we will see when he gets the rifle back but I will bet its just fine.

 

[J E Custom]

The first thing to move when the cartridge is fired is the primer to the rear until it contacts the bolt face. Then as the chamber pressure increases to the yield strength of the brass the case stretches to meet the bolt face.And on lower pressure cartridges the primer will always protrude by the amount of head clearance you have.

I'm seriously beginning to doubt your knowledge on firearms by your statements you have posted in this forum.

You can doubt all you want. the case head has considerable more square inches of surface than the flash hole and will move long before the primer even sees enough pressure to move it and by the time pressure get high enough the case is already slammed against the bolt face preventing any movement and sealing the primer. also if the primer moved, it would leak and carbon would be present where it had been. it would also gas cut the primer pocket. it is a simple mater of physics, the bigger piston with more surface will always move first.

That's a nice picture but it is simply not true.

I'm sorry that you want to get personal, because my rebuttal to your statements gave you a way to correct your post on head space and the .064 to .074 thousandths of head space that was normal for a 303, gracefully and you didn't take it. so I will make one more statement and I will let you impress all that don't know better and rely on real gunsmiths to steer them in the right direction. I have never claimed to know everything and learn many things on this site. so please don't try to convince any one that knows any thing about reloading and building firearms that that we should set head space using a primer and 64 to 74 thousandths is the normal head space.

Firing pins don't extend that much (Somewhere between ,055 and .065 thousandths) and if head space was that much the firing pin would not reach the primer unless you shot straight up every time, and then you would only get one shot before someone had to call an ambulance.

I don't know your background so I cant comment on your knowledge
as far as building rifles, but I will say that anyone that sets head space with a primer Is not or will never be a gunsmith.

My apologies to the membership for this reply. but sometimes we have to speak up when someone gets personal that don't know better. we are responsible for what we tell the newbies that could hurt them or mislead them so don't believe me if you don't want to but just ask other gunsmith how they set head space and how much they can live with.

Sorry you doubt my knowledge on firearms but I learned what little I know buy doing it for over 55 years and building hundreds of rifles, not on the internet.

J E CUSTOM

 

[MagnumManiac]

You can doubt all you want. the case head has considerable more square inches of surface than the flash hole and will move long before the primer even sees enough pressure to move it and by the time pressure get high enough the case is already slammed against the bolt face preventing any movement and sealing the primer. also if the primer moved, it would leak and carbon would be present where it had been. it would also gas cut the primer pocket. it is a simple mater of physics, the bigger piston with more surface will always move first.

That's a nice picture but it is simply not true.

I'm sorry that you want to get personal, because my rebuttal to your statements gave you a way to correct your post on head space and the .064 to .074 thousandths of head space that was normal for a 303, gracefully and you didn't take it. so I will make one more statement and I will let you impress all that don't know better and rely on real gunsmiths to steer them in the right direction. I have never claimed to know everything and learn many things on this site. so please don't try to convince any one that knows any thing about reloading and building firearms that that we should set head space using a primer and 64 to 74 thousandths is the normal head space.

Firing pins don't extend that much (Somewhere between ,055 and .065 thousandths) and if head space was that much the firing pin would not reach the primer unless you shot straight up every time, and then you would only get one shot before someone had to call an ambulance.

I don't know your background so I cant comment on your knowledge
as far as building rifles, but I will say that anyone that sets head space with a primer Is not or will never be a gunsmith.

My apologies to the membership for this reply. but sometimes we have to speak up when someone gets personal that don't know better. we are responsible for what we tell the newbies that could hurt them or mislead them so don't believe me if you don't want to but just ask other gunsmith how they set head space and how much they can live with.

Sorry you doubt my knowledge on firearms but I learned what little I know buy doing it for over 55 years and building hundreds of rifles, not on the internet.

J E CUSTOM

No need to apologise, we know your experience J E CUSTOM.

If I had have seen this thread earlier, I would have said the marks on the brass are normal, caused by the chamber and the solid web portion not expanding and touching the chamber. The same marks happen when a case is sized, the dull area touches the die and the shiny area doesn't.
This is very normal.

A case head separation normally starts well above the expansion line, some 1/4" of an inch above the web, it is noticeable as a wide yellow line where the stretching is occurring.

Cheers.

 

[Barrelnut]

No need to apologise, we know your experience J E CUSTOM.

If I had have seen this thread earlier, I would have said the marks on the brass are normal, caused by the chamber and the solid web portion not expanding and touching the chamber. The same marks happen when a case is sized, the dull area touches the die and the shiny area doesn't.
This is very normal.

A case head separation normally starts well above the expansion line, some 1/4" of an inch above the web, it is noticeable as a wide yellow line where the stretching is occurring.

Cheers.

All of this was said earlier.

 

[TwoMore]

bumping the shoulder back on a already shorter case could be a problem. one of the biggest problems I see with guys I help who have similar problems is they are bumping far to much because they have their number wrong and usually to short. I helped an Uncle out this week and he was actually bumping over .010 and thought he was bumping .002. from the chamber shoulder, he had to trim a lot, and cases were not lasting very long. His die was not sizing the diameter enough and was bumping the shoulder to much. (.300 rum) we used my dies and figured it out. by the way he would have misfires quite often with this rifle on his reloads, when he told me that a light came on in my head lol. Edit I will add My Uncle is a great guy but gets confused easily

On the primer moving, can it move before it ignites the powder under its own energy? I ask because the rifle I helped my Uncle would flatten primers pretty bad and when we got him back in the realm of the correct case length (headspace)It quit flattening the primers.

 

[Pdvdh]

On the primer moving, can it move before it ignites the powder under its own energy? I ask because the rifle I helped my Uncle would flatten primers pretty bad and when we got him back in the realm of the correct case length (headspace)It quit flattening the primers.

Yes. They typically move back to the extent any excess headspace allows for it. Then as pressure builds the case head moves back with greater force and flattens the protruding primer like a hammer.

 

[L.Sherm]

In post #60 you state you are FL sizing with your die touching the shell holder +1/4 turn, sounds like to me either die is not matching your chamber very well or your bumping alot.

 

[Lonewolf74]

Aright guy's I've read through this whole thread and something has caught my attention.

The op said (post 60) the brass grew .012 when fired, NOT when sized! The growth from sizing was .006, he has all measurements down so I have to believe this is happening but, should not be.

So for starters to the op, are you sure you trimmed your brass to 2.025 before it was loaded and fired? And doubly sure it grew .012 without anything being done except firing the case???

To everyone else, what could cause a case to grow like this just from firing?

 

[timberelk]

Aright guy's I've read through this whole thread and something has caught my attention.

The op said (post 60) the brass grew .012 when fired, NOT when sized! The growth from sizing was .006, he has all measurements down so I have to believe this is happening but, should not be.

So for starters to the op, are you sure you trimmed your brass to 2.025 before it was loaded and fired? And doubly sure it grew .012 without anything being done except firing the case???

To everyone else, what could cause a case to grow like this just from firing?

I'm 99% sure I trimmed after I sized but that is the only step I didn't completely document and I want to be 100% sure so before I send the gun to the gun smith I'll try to load up a few rounds and ensure they are trimmed to .025 right before I shoot them

 

[Lonewolf74]

Yes double check and test for this. Everything else you have is fine and normal.

 

[L.Sherm]

To everyone else, what could cause a case to grow like this just from firing

Bumping back to far I have done it myself going off of a bad number. It wasn't until I had a case head separation that I started investigating more and discovered the problem.

Aright guy's I've read through this whole thread and something has caught my attention.

The op said (post 60) the brass grew .012 when fired, NOT when sized! The growth from sizing was .006, he has all measurements down so I have to believe this is happening but, should not be.

So for starters to the op, are you sure you trimmed your brass to 2.025 before it was loaded and fired? And doubly sure it grew .012 without anything being done except firing the case???

To everyone else, what could cause a case to grow like this just from firing?

 

[timberelk]

Bumping back to far I have done it myself going off of a bad number. It wasn't until I had a case head separation that I started investigating more and discovered the problem.

How do I have bad numbers? I'm measuring fired cases from my gun and I'm using the Hornady comparator guage so I can measure how far the shoulder is pushed back which is .002"

 

[Lonewolf74]

Also how are you measuring the shoulder of the case? Where does the .626 measurement come from? Do you mean 1.626 and that is the length from cartridge base to shoulder datum (using the hornady case length measuring tool)?

 

[timberelk]

Also how are you measuring the shoulder of the case? Where does the .626 measurement come from? Do you mean 1.626 and that is the length from cartridge base to shoulder datum (using the hornady case length measuring tool)?

I'm using hornday comparator guage to measure the shoulder