Soot On Cases

[Barmcd]

I thought soot at the mouth of a fired case was caused by low charge weights not sealing the case in the chamber and was unavoidable when shooting softer target loads. Then I loaded 148 gr. plated wadcutters at pretty low charge rates of 4.0, 4.2, 4.4 and 4.6 grains of HP-38. Those cases were surprisingly clean compared to the ones I fired with 5.4 grains of HP-38 and a 125 gr. plated FN bullet.

In this video, the first case was a 125 gr. Berry's plated bullet powered by 5.4 grains of HP-38. The next four were 148 gr. Berry's plated wadcutter powered by 4.0, 4.2, 4.4, and 4.6 gr. None of those cases exhibit the sooty mouth like the higher powered 125 gr. bullet. How is it the case with the higher charge has more soot on it than those with lower charges?

 

[Walkalong]

That isn't bad at all.

 

[GeoDudeFlorida]

I thought soot at the mouth of a fired case was caused by low charge weights not sealing the case in the chamber and was unavoidable when shooting softer target loads. Then I loaded 148 gr. plated wadcutters at pretty low charge rates of 4.0, 4.2, 4.4 and 4.6 grains of HP-38. Those cases were surprisingly clean compared to the ones I fired with 5.4 grains of HP-38 and a 125 gr. plated FN bullet.

In this video, the first case was a 125 gr. Berry's plated bullet powered by 5.4 grains of HP-38. The next four were 148 gr. Berry's plated wadcutter powered by 4.0, 4.2, 4.4, and 4.6 gr. None of those cases exhibit the sooty mouth like the higher powered 125 gr. bullet. How is it the case with the higher charge has more soot on it than those with lower charges?

I think you have just demonstrated the reality of common ballistics: there are no absolutes.
The lack of a seal or presence of “soot” at the case mouth can also be attributed excessive roll crimp, hardness of the brass, flaws in the cylinder, differences in case length and a variety of other causes. Anything which exposes a portion of the case mouth to burning gases can discolor the exposed area.
But mostly, there are no absolutes where controlled deflagration is concerned.

 

[jmorris]

Try VV powders, if you want clean, N310&320 are good for 9mm and plated bullets. At least new W231/HP-38 is cleaner than the old metal can stuff…

 

[Palladan44]

I see no issue. In fact that looks quite clean.

 

[AJC1]

The faster the powder you use in low pressure loads the better. An excessive pressure spike is never good, but a full pmax seals the brass to the chamber walls with low recoil and low velocity.

 

[film495]

the case with the soot in my expereince looks more normal/common than the clean looking ones, factory and reloaded

 

[Bazoo]

I've never seen fired cases that were that clean. The first case is a "normal" one. I didn't see mention of what brand of cases they are.

If they are not all the same headstamp from the same lot, fired the same amount of times, it will most likely exhibit different amounts of soot.

 

[W.E.G.]

HP-38 and Winchester 231 are the same powder.

Both burn very dirty.

 

[GeoDudeFlorida]

The faster the powder you use in low pressure loads the better. An excessive pressure spike is never good, but a full pmax seals the brass to the chamber walls with low recoil and low velocity.

Er-hem… TiteGroup.
I think the OP was asking about why they are different and supposedly “backwards” - lower pressure load cleaner than higher pressure, etc. - not just how clean or dirty. I don’t think there’s a hard and fast, written in stone, Thou shalt not… answer. It’s nitro. Anything that exposes a portion of the case rim to hot gases can cause discoloration.
Changing powders and crimping and undersizing/oversizing may change the pattern but at what cost?
If a good load is “dirty” then clean the gun/brass more often.

By the way, gravity is also a factor. The cartridge is laying in the chamber at the time of ignition. That means the top has a greater air-gap than the bottom of the case mouth. Think about that.

 

[BBarn]

Differences in bullet weights, bearing surface, seating depths, and powder charge. Likely differences in pressure as well. So not surprising.

 

[N555]

Depending on the powder you can get soot of you load too light or too hot.
30carbibe will do it with AA9 with too little and too much.

 

[AJC1]

Er-hem… TiteGroup.
I think the OP was asking about why they are different and supposedly “backwards” - lower pressure load cleaner than higher pressure, etc. - not just how clean or dirty. I don’t think there’s a hard and fast, written in stone, Thou shalt not… answer. It’s nitro. Anything that exposes a portion of the case rim to hot gases can cause discoloration.
Changing powders and crimping and undersizing/oversizing may change the pattern but at what cost?
If a good load is “dirty” then clean the gun/brass more often.

By the way, gravity is also a factor. The cartridge is laying in the chamber at the time of ignition. That means the top has a greater air-gap than the bottom of the case mouth. Think about that.

Initial cleanliness of the chamber to make a good seal is probably a bigger factor than gravity.... dirt/fouling seems self perpetual. My ignorance on chemical effects will pump my breaks on any related effects in that area. Know what I don't know.

 

[GeoDudeFlorida]

Initial cleanliness of the chamber to make a good seal is probably a bigger factor than gravity.... dirt/fouling seems self perpetual. My ignorance on chemical effects will pump my breaks on any related effects in that area. Know what I don't know.

I didn’t mention scale of effect and don’t intend to. It’s a factor. That’s all.

 

[JFrank]

Looks like the 148gr sealed better than the 125 gr. Not sure if one has a larger pressure ring or not.

 

[entropy]

If there is a ring of crud in the chamber from firing other rounds that come out sooty at the mouth, those rounds will leave a semi-hardened layer that subsequent cases will acquire part of on firing.
Bore solvent followed by a light chamber polish will reduce this, but it will keep coming back without diligent attention to the chambers. It doesn't take a thick layer for it to happen.
As others have said, I don't think that looks too bad, I've seen much worse.

 

[film495]

what are you testing for overall? what is the point of the .2 grain ladder? did they all seem to fire correctly and hit the target?

 

[GW Staar]

I shoot a lot of .45ACP with Unique powder. Never even thought about soot as anything abnormal, until the internet came along.....suddenly my favorite pistol powder is maligned as "dirty" and accuracy and Unique's insensitivity to exact volume to get that accuracy is suddenly "less" important. I still love to load and shoot with Unique, and I ignore the soot. Least until it's time to clean the pistol and/or reload the cases......both are commonly done, visible soot or not.

 

[CQB45ACP]

I shoot a lot of .45ACP with Unique powder. Never even thought about soot as anything abnormal, until the internet came along.....suddenly my favorite pistol powder is maligned as "dirty" and accuracy and Unique's insensitivity to exact volume to get that accuracy is suddenly "less" important. I still love to load and shoot with Unique, and I ignore the soot. Least until it's time to clean the pistol and/or reload the cases......both are commonly done, visible soot or not.

I shoot 45 too but never with unique. Now I might out of solidarity. Low charges of sport pistol are also very dirty but who cares? I only load my cases once they’re jewelry like anyway so some soot, a lot of soot or little soot is all the same to me.

 

[Barmcd]

the case with the soot in my expereince looks more normal/common than the clean looking ones, factory and reloaded

It does to me too, hence the questions about the other cases.

 

[Barmcd]

I've never seen fired cases that were that clean. The first case is a "normal" one. I didn't see mention of what brand of cases they are.

If they are not all the same headstamp from the same lot, fired the same amount of times, it will most likely exhibit different amounts of soot.

They are all brand new Starline cases out of the same bag.

 

[Barmcd]

Er-hem… TiteGroup.
I think the OP was asking about why they are different and supposedly “backwards” - lower pressure load cleaner than higher pressure, etc. - not just how clean or dirty. I don’t think there’s a hard and fast, written in stone, Thou shalt not… answer. It’s nitro. Anything that exposes a portion of the case rim to hot gases can cause discoloration.
Changing powders and crimping and undersizing/oversizing may change the pattern but at what cost?
If a good load is “dirty” then clean the gun/brass more often.

By the way, gravity is also a factor. The cartridge is laying in the chamber at the time of ignition. That means the top has a greater air-gap than the bottom of the case mouth. Think about that.

That's exactly what I was asking as I have never seen a case that clean after firing.

 

[Barmcd]

If there is a ring of crud in the chamber from firing other rounds that come out sooty at the mouth, those rounds will leave a semi-hardened layer that subsequent cases will acquire part of on firing.
Bore solvent followed by a light chamber polish will reduce this, but it will keep coming back without diligent attention to the chambers. It doesn't take a thick layer for it to happen.
As others have said, I don't think that looks too bad, I've seen much worse.

Initial cleanliness of the chamber to make a good seal is probably a bigger factor than gravity.... dirt/fouling seems self perpetual. My ignorance on chemical effects will pump my breaks on any related effects in that area. Know what I don't know.

I have shot about 100 rounds out of the gun since the last real cleaning. I shot 18 test loads of the 148 gr. Berry's wadcutter and then shot the 125 gr. Berry's FN so they were shot pretty close together.

 

[Barmcd]

Looks like the 148gr sealed better than the 125 gr. Not sure if one has a larger pressure ring or not.

I wondered if the pressure was too high on the 148 gr. wadcutter loads, but the velocities and appearance of the primers after firing lead me to believe its not too high.

 

[Barmcd]

what are you testing for overall? what is the point of the .2 grain ladder? did they all seem to fire correctly and hit the target?

I'm loading these 148 gr. Berry's Wadcutters for the first time. I normally use published data for jacketed bullets when loading plated bullets, but there is no data anywhere for jacked or plated Berry's wadcutters. I got creative and used my own load data from 158 gr. Berry's FN plated bullets. I use 4.4 gr. of HP-38 for that bullet and get about 750 FPS. I measured the length of both bullets and set the COAL of the 148 gr. bullet to give me the same volume in the case behind the bullet as I get with the 158 gr. bullet. Then I backed off of my normal 158 gr. load slightly and made a small ladder looking for 700 FPS. That's the velocity I chose since I'll be shooting these exclusively in a 38 special target pistol. I got a little more velocity out of the wadcutter, probably because its 10 gr. lighter and a tenth of an inch shorter, reducing friction in the barrel.





On edit: After looking at the pics of the two bullets, I can see that the friction on the wadcutter wouldn't be less than the 158 gr. bullet so that blows that theory.