Soot on case neck?

Feidhlim Dignan

i have noticed that on some of the fired cases from my cz 527 .223 have soot on the case neck, what dose this mean is there a problem?
the gun is only 9 months old and has only fired about 50 rounds

Cass

I know you said the neck, but is it on the neck only or the neck & shoulders?

If its on the neck i wouldn't worry. If its on the shoulders there could be a problem.

Feidhlim Dignan

just till about half way down the case.
you think its fine?
any idea what causes it?

Cass

Feidhlim Dignan wrote: »

just till about half way down the case.

I don't mean to be pedantic, but there is a difference. The case is the entire shell. Is it coming half way down the neck ONLY or is it getting as far as the shoulders or further?

Feidhlim Dignan

sorry half way down the neck, big difference alright

Cass

I imagine its a case of a low charge in the ammo. In other words not enough pressure to create a "proper" or "perfect" seal when the shot is fired.

Its nothing worth worrying about and will not cause any damage. Its a simple factory ammo issue. i had it a while ago with Sako ammo in 6.5x55.

Try different ammo, and not just a different box of the same brand but a different brand. Problem should disappear.

FISMA

Feidhlam,
Hornady has an excellent manual with a nice description as to what is going on internally when the shot is fired. Have a look at this link http://www.hornady.com/ballistics-resource/internal

What kind of ammo are you shooting? Is it cheap stuff - like Wolf, Brown Bear, or the like? If so, that might be the problem there. I am not above shooting cheap ammo. I just don't do it as much as I used to as I notice a big difference in cleaning when it comes to Wolf Vs Hornady.

To be honest, I am unsure when and where fouled cases starts to become a concern. I have no disagreement with Ez and find him to be an excellent source of unbiased info.

Still, I have to wonder, at what time, if at all, during the process has the case contracted enough to allow residual soot to foul the case.

If you look closely at the below image, you will see a small bit of whitespace (greatly exagerated) surrounding the body of the round. Moreso on the top than the bottom. The round has not yet been fired and fits "loosely" in the chamber.

Again, check out the above link, it is where the images come from.

Next, you pull the trigger, strike the primer, and ignite the powder. Before the bullet leaves the brass there is a lot of pressure. So much that the pressure causes the expansion of the brass. This pressure is so great that the brass "inflates" to fill the whitespace mentioned previously.

I think what Ez is saying, and if so I agree, is that if you are getting fouling on the body, that is concerning as one would expect the neck, shoulders and fore end of the body to have inflated to a point that would create a gas seal, let alone a seal that would block out small solid particles.

Also, Ez is saying - you may be under-powered, under-powdered, and hence under-pressured. This could be a major concern if a bullet hangs in the barrel. If this happens and a second shot is taken, you will have a catastrophic failure which could result in death. Seriously.

This is why you should always try and follow your rounds to the paper and confirm the new hole on the target.

This almost happened to me once with a 9mm using Wolf ammo. Fortunately, there was a significant lack of recoil, the action failed to cycle, and the bullet did not get into the barrel. I think they missed the powder altogether and the round was expelled on primer alone.

Back on topic - I am unsure as to when the cartridge deflates enough to allow gasses and soot to foul the body of the brass - before the bullet clears the barrel or after?

I would assume that when the bullet is still in the barrel there is back pressure which could cause fouling on a contracting case.

Another simpler theory would be loading bullets into a dirty chamber!

Can you post some images?

Parts

Cass

FISMA wrote: »

I think what Ez is saying, and if so I agree, is that if you are getting fouling on the body, that is concerning as one would expect the neck, shoulders and fore end of the body to have inflated to a point that would create a gas seal, let alone a seal that would block out small solid particles.

Also, Ez is saying - you may be under-powered, under-powdered, and hence under-pressured. This could be a major concern if a bullet hangs in the barrel. If this happens and a second shot is taken, you will have a catastrophic failure which could result in death. Seriously.

Correct on both accounts.

If the neck has a small bit of fouling on it there is no concern as long as the shoulders and body remain "fouling free". This means the shoulders and body are creating a sufficient seal irrepsective of the neck.

If the fouling did make it down the shoulders and even onto the body then i would definitely stop shooting. Most likely it is the ammo, but as said already its a somewhat serious issue and you do not want a second bullet trying to go down the barrel when the first COULD possibly be stuck.