The Firing Line Forums

Go Back   The Firing Line Forums > Hogan's Alley > Handguns: The Semi-automatic Forum

Reply
 
Thread Tools Search this Thread
Old November 11, 2019, 03:34 PM   #1
HighValleyRanch
Senior Member
 
Join Date: July 15, 2005
Posts: 3,444
curious scorching on brass

Shooting out a Kahr P45 with a Lothar Walther match barrel.
I noticed after shooting new factory brass, that each casing has a blackish scorch mark on one side of the brass. Just curious what is causing that?
What's you opinion?

Functions perfectly, and accurate. But cursious when in the timing would there be opportunity for the case to get scorch and how, since it's in the chamber at the time of the powder being burned.
__________________
From the sweet grass to the slaughter house; From birth until death; We travel between these two eternities........from 'Broken Trail"
HighValleyRanch is offline  
Old November 11, 2019, 03:44 PM   #2
TailGator
Senior Member
 
Join Date: May 8, 2009
Location: Florida
Posts: 3,656
Do you mean soot? Most common cause of that is incomplete obturation. Are the rounds a little on the low power side? It doesn't worry me when I see it.
TailGator is offline  
Old November 11, 2019, 03:49 PM   #3
Dan-O
Senior Member
 
Join Date: August 3, 2011
Location: Northern Colorado
Posts: 864
I get the same when shooting some powder puff reloads.

Factory loads? If so, what kind?
Dan-O is offline  
Old November 11, 2019, 03:55 PM   #4
HighValleyRanch
Senior Member
 
Join Date: July 15, 2005
Posts: 3,444
They are PMC and not powder puff loads.
So is it because the case does not expand fast enough to fit the chamber before the power burns?
__________________
From the sweet grass to the slaughter house; From birth until death; We travel between these two eternities........from 'Broken Trail"
HighValleyRanch is offline  
Old November 11, 2019, 04:28 PM   #5
Dan-O
Senior Member
 
Join Date: August 3, 2011
Location: Northern Colorado
Posts: 864
Exactly
Dan-O is offline  
Old November 11, 2019, 04:44 PM   #6
dyl
Senior Member
 
Join Date: October 31, 2009
Location: Ohio
Posts: 1,006
Quote:
So is it because the case does not expand fast enough to fit the chamber before the power burns?
I believe so, and that less than max pressure is developed to make the brass flow as much as it normally would. I usually see this in my lighter reloads (when my Lee auto disk doesn't have the optimum choice) and in steel casings which are a little stiffer.

If it's practice ammo, I think the soot would stop if it were loaded a little hotter. Maybe try a couple premium rounds and see. My cases never come out completely sparkly though, it might be the fast powder burn rate and short barrels I've been shooting the past few years. You could try your PMC rounds in a longer barrel and see if the extra length allows for a cleaner or more complete burn.

I'm guessing it's not the barrel/chamber unless there are nasty machining marks everywhere. But it's a Lothar Walther so probably not.
dyl is offline  
Old November 11, 2019, 04:49 PM   #7
GlenF
Member
 
Join Date: April 4, 2011
Location: Lawrence, Kansas
Posts: 75
Or, it may be due to the power used.

I have used CFEpistol for a few years, and it will cause a blackish residue on the outside of 9mm cases. And, I am over the maximum grains that Hodgdon recommends.
GlenF is offline  
Old November 11, 2019, 04:55 PM   #8
HighValleyRanch
Senior Member
 
Join Date: July 15, 2005
Posts: 3,444
I remember from my bullseye days that bullseye and unique powders were pretty dirty.
I was just wondering, though why it was just on one side of the case. There was no way to determine if it's always the same side, but they all look pretty identical, instead of radom sooting. Made we wonder if the chamber was oblong somehow? The chamber is fully supported and the sooting is on the bullet end, not the rim end.
__________________
From the sweet grass to the slaughter house; From birth until death; We travel between these two eternities........from 'Broken Trail"
HighValleyRanch is offline  
Old November 11, 2019, 05:17 PM   #9
dyl
Senior Member
 
Join Date: October 31, 2009
Location: Ohio
Posts: 1,006
I had originally typed about your casings or chamber being out of round but then deleted it because I thought that properly fire formed brass would cover that problem. After all, 40 cal brass that has been Glock'd swells up significantly.

Quote:
There was no way to determine if it's always the same side, but they all look pretty identical,
There is a way. I've seen someone do this on YouTube on precision AR reloads (6.5 Creedmoor I think?) to make sure that oblong cases or deviated bullets were always loaded pointing the same direction in the chamber. To make up for imperfections in the reloading process. He measured things first, you wouldn't have to do that, just draw a line.

You could draw a black Sharpie line up one side of the brass and load it into your mag so the line is pointing up. Do this for all the rounds and load your mag so all the lines are at the top. Then you'd have a landmark to see where the soot occurs relative to the top of the case. I don't think the cases will rotate much on just chambering.
dyl is offline  
Old November 11, 2019, 05:30 PM   #10
HighValleyRanch
Senior Member
 
Join Date: July 15, 2005
Posts: 3,444
Excellent idea. I will also try them in my glock 21 to see if there is a difference.
Not worried about, mostly curious what is happening.
__________________
From the sweet grass to the slaughter house; From birth until death; We travel between these two eternities........from 'Broken Trail"
HighValleyRanch is offline  
Old November 11, 2019, 10:52 PM   #11
44 AMP
Staff
 
Join Date: March 11, 2006
Location: Upper US
Posts: 20,465
Quote:
So is it because the case does not expand fast enough to fit the chamber before the power burns?
this is possible. There is a second possibility, and that is, things are working normally.

Yes, the soot is from powder gas getting between the case and the chamber wall, and this CAN happen before the case seals to the chamber.

BUT, it can ALSO happen when the case "unseals" (springs back) as the pressure drops. powder gas is still there, and can mark the case before the extractor pulls it out of the chamber. This is normal. Some powders simply are much dirtier about it than others.
__________________
All else being equal (and it almost never is) bigger bullets tend to work better.
44 AMP is offline  
Old November 12, 2019, 01:49 AM   #12
pwc
Senior Member
 
Join Date: March 21, 2018
Location: AZ
Posts: 107
Sounds like lo power loads. Carefully llad mag pr i tp chamber with same headstamp orientation to see the mark.
pwc is offline  
Old November 12, 2019, 12:10 PM   #13
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 769
I had exactly the same issue with a Browning 1911-380 Auto. I using 3.2gr (max)of Titegroup with a Hornady 90gr XTP HP. The cases were tarnished solid black around one-half of the case. One of the references suggested seating at 0.980" which I did. I found another that recommended 0.955". I seated the bullets deeper and resolved the problem.
cdoc42 is offline  
Old November 12, 2019, 02:32 PM   #14
T. O'Heir
Senior Member
 
Join Date: February 13, 2002
Location: Canada
Posts: 11,572
"...case does not expand fast enough..." Isn't about how fast. It's about expanding at all or incompletely.
That .980" is likely the issue. The MAX OAL for the .380 is .984".
__________________
Spelling and grammar count!
T. O'Heir is offline  
Old November 12, 2019, 09:21 PM   #15
cdoc42
Senior Member
 
Join Date: March 13, 2005
Location: Pennsylvania
Posts: 769
" The MAX OAL for the .380 is .984".

It must depend on the gun. The Hodgdon site for .380 Auto lists COL at 0.970" for a 90gr HDY JHP with CFE Pistol, but with HP-38 and TiteGroup, the same bullet is seated at 0.955".

The difference is the powder and pressure I suppose but my pistol did not function with Titegroup at 0.980. Maybe it would at 0.970, but it sure does at 0.955"
cdoc42 is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 07:13 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2018 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.07181 seconds with 10 queries