Black around the neck after firing and low pressure signs

[ailar]

Hi,

Bouncing off another topic which touched on this - viewtopic.php?f=3&t=835

When firing my loads there is a bit of black residue around the brass necks after firing.

I have the short version of the story that this can be a sign of low pressure, but don't know why?

Why does a little powder residue = low pressure?

Thanks.

[Baldrick314]

It can be a sign of low pressure but it also occurs with normal pressure loads. It's normal to have some black residue around your case necks but too much can be indicative of low pressure

[Norton]

Like Baldrick said, it can be indicative of low pressure, but it's not definite.

In cases of low pressure, it's because there is not enough pressure to seal the brass to the chamber and the burning powder fills and leaves a residue between the brass and chamber.

A little bit shouldn't be anything to worry about though.

[Monty]

A little bit shouldn't be anything to worry about though.

If it's just on the neck it's probably not a big deal.

If it reaches the shoulder it's definitely worth checking.

If it reaches the body you've really got something wrong.

[Bills Shed]

I agree with all of the above.

Low pressures tend to leave the outside of the cases "sooty", where you can easily wipe the soot off with your thumb.

Normal pressure loads tend to blacken the neck only and the blackened area is far harder to wipe off.

If the body is blackened, stop and check everything.

Bill.

[Hercl]

Low pressures tend to leave the outside of the cases "sooty", where you can easily wipe the soot off with your thumb.

If only cleaning all brass was so easy.

I'm so sick of hearing my tumbler rumbling for the last 6 hours