Home Forums Reloading Big Game Rifles Soot on case

Why would a person get powder residue(soot) down by the case rim after firing?

What is the cartridge? Any other details? I'm not sure myself. I would think it would be something with the primer or primer pocket? Just a guess with no other real idea.

It's my friends rifle and we shot a few that day, I believe the cartridge was 25-06. The residue isn't around the primer or headstamp, it's more in the rim area.

The reason I ask is, he talked to someone from the manufacturer and they gave him a reason for this that I've never heard before. And I wont repeat it here because it's wild in my opinion.

I'll see that occasionally... never thought much of it.

But why only on one particular rifle?

Factory ammo and the same ammo didn't do it in another rifle??

Any powder residue around the neck?

Reloads. Nothing on the neck. All down below in the "curvature" around the rim.

Never heard of it. I'm curious about the bizarre reason the factory gave you that you won't repeat.

My first thought when I see that is low pressure.

Usually low pressure. Without seeing the case, it's difficult to tell.

Ones cartridges are not expanding sufficiently to seal the chamber. Some brands of brass are thicker than others. Might try resizing and then annealing the necks and maybe down into the shoulder.

yeah... and if that doesn't work, you might need to heat things up a bit w/ the load... if the soot matters that much to you and the load he is running isn't accurate enough. If it is accurate and hot enough, oh well... soot won't hurt anything...

IME, if it`s the first few shots out of a clean rifle that`s been standing on the butt stock, the cause can be oil or cleaning fluid from the barrel running down into the chamber.The fluid dosen`t compress when the gun is fired, and some soot catches around the rim, or in front of the case head.
Run a clean patch into the chamber...it will come out black.

Knowing this can happen to rifles stored in this fashion, I always run a patch into my chambers befor firing...just to be safe.

Low pressure huh? Then maybe everyone is on the same page.

The Tech was talking about cold temps, he wanted to know what was the ambient temp the day we were shooting,which was right around freezing. Something about the brass being "cold". That was sounding weird to me.

But if not enough pressure, and the case isn't expanding, then we are getting the residue from that?

The Tech did talk about using a faster/hotter powder. so then I guess this would expand the case even more and seal the chamber.

Making any sense?

Myself, I was thinking headspace issue..

Low pressure was what I was thinking when I asked the questions, but mine have typically had residue around the case neck.....not the base of the case around the rim.

Have you guys saying not enough pressure to expand the case seen this before with residue near the case head? I've never seen that.

funny you bumped this up, I was just thinking about this.

I was shooting with the same guy today, same rifles.

The cartridge in question is a .204 Ruger, he is shooting Berger bullets and 335(I think) powder,

Typical load development, start low and increase by 1/2 grain increments.

The lowest weight charge shows just a touch of soot by the rim, as the charge increases, the soot increases,

which kinda offsets the low pressure theory...

Talk to me..........

Yes. Also seen cases with the sides caved in somewhat due, again, to low/inadequate sealing pressure.

Find the particulars of the load, such as the brand of case, powder, the charge amount, bullet, and OAL. I, or anybody with QL, could give you a ballpark figure on pressure.

Or, the brass could be more-than-usual brittle.

In either instance, the case is not sealing against the chamber walls.

I've had soot happen with starting loads using slow (for cartridge) powder sometimes. Never really thought about it, perhaps a little gas blows by before things really get cooking and pressure seals the case.

Perhaps not, just a thought.

Yep, I've seen that at the shoulder before.