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Discussion Starter · #1 · (Edited)
I've been reloading my 9mm cases and have noticed an odd thing.

On cases in which I have used either Bullseye or Titegroup, I get some significant discoloration on the outside of the case, but only on one side of it. It can extend 1/4" or more down from the case mouth.

When I use Unique, however, there's very little of that, if any at all.

I'm not overloading any of these rounds; I'm not really very close to max charge.

Below are pics that show what I mean; the Unique cases look worse in the pic than they are. This is typical, and not the first time I've seen it.

Any idea what's going on? I'm using FMJBT bullets from Delta, the ones with the exposed lead base. I know the burn rates for Bullseye and Titegroup are faster than Unique, but I don't understand why the case discoloration.







 

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Uberfast powders burn very hot, TG, BE, Clays, etc. They tend to leave flash burn marks on the mouth of the case. You could try crimping a bit more, but it is likey to not help. It's one reason NOT to use them w/ lead bullets too. The high burn temp melts the base of the bullet & you get leading @ the beginning of the rifling.
 

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Nothing to worry about. I've seen it a lot in the .41 (although more with comparitively slow powders like W296 and H110) . I've seen it referred to as "smoked" in old gun articles. It will clean right off in the tumbler.
 

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Nothing to worry about. I've seen it a lot in the .41 (although more with comparitively slow powders like W296 and H110) . I've seen it referred to as "smoked" in old gun articles. It will clean right off in the tumbler.
ThaT is more soot than "burn" on slow powder in the magnums, more crimp or more powder to get the pressure up where it will seal off the case/chamber.
 

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my dads reloads do the same thing
 

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Discussion Starter · #9 ·
I've got a tumbler. That's how I clean the brass prior to sizing and decapping.

The issue was whether I have a problem with either the kind of powder I'm using, or if there's something else going on that's problematic, since I don't see this issue when I use rounds loaded with Unique, nor have I noticed this with factory loaded ammunition, which brass I collect for reloading.
 

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Lower powder charges don't expand the shell to fill the chamber so some soot blows back down the shell. Totally normal.

+1, Thats my experience, lighter loads dont seal the chamber quite as fast and you get a little soot on the outside,

Not a problem..........
 

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Lower powder charges don't expand the shell to fill the chamber so some soot blows back down the shell. Totally normal.
+1

not enough pressure in those loads to make the brass expand in the chamber hence blow back which is why your cases looked "smoked".

pete

115 grain FMC
Bullseye 4.3 gr. 1,180 FPS
Unique 6.1 gr. 1,185
Universal 5.0 gr. 1,149
Clays 3.9 gr. 1,095
HP38 5.1 gr. 1,167
No. 2 4.4 gr. 1,092
No. 5 7.0 gr. 1,192
231 4.2 gr. 1,135
WSL 4.5 gr. 1,105
WSF 5.7 gr. 1,165
WAP 6.0 gr. 1,162
VV N350 6.0 gr. 1,130

Reloading 9 MM Luger Page
 

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I get pretty much the same with 4.1 of TG pushing a 124 DP FMJ RN
 

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I've started using a resizer die (of appropriate caliber w/o the de-caper) in the final station of a Dillon 550. This gives it the same final crimping and shape as a factory crimp. A 9mm measures .373 at the mouth of the case of Winchester brass, my normal crimp load was SAMMI specs of .378. This .373 final crimp reduced the back flash burn marks considerably. I have rationalized that it seals better and obdurates slower, resulting in higher pressures, but a much more cleaner, complete burn and accurate bullet. If you do this, I would not suggest that you load it to the minimum COL. The case is sized slightly small and the tension of the case around the bullet holds the bullet in place. You could also use a Lee FCD for a final station taper crimp.
 

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Discussion Starter · #15 ·
I've started using a resizer die (of appropriate caliber w/o the de-caper) in the final station of a Dillon 550. This gives it the same final crimping and shape as a factory crimp. A 9mm measures .373 at the mouth of the case of Winchester brass, my normal crimp load was SAMMI specs of .378. This .373 final crimp reduced the back flash burn marks considerably. I have rationalized that it seals better and obdurates slower, resulting in higher pressures, but a much more cleaner, complete burn and accurate bullet. If you do this, I would not suggest that you load it to the minimum COL. The case is sized slightly small and the tension of the case around the bullet holds the bullet in place. You could also use a Lee FCD for a final station taper crimp.
I am using a Lee FCD to finish (chrono results showed a much more consistent velocity using the taper crimp).

Given what I've learned here, I'll probably try some variations. I was most concerned that there was something wrong but apparently, as Microsoft used to say, it's a feature not a bug.

Thanks to all!
 

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Lower powder charges don't expand the shell to fill the chamber so some soot blows back down the shell. Totally normal.
THe low powder charge means nothing. It's the pressure generated. TG charge wt. is approx. 25% less than Unique, both have sim. pressures.
 

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Straight walled pistol cases like 9mm and even 45 ACP's do this because they do not seal the chamber fast enough to stop some of the gas from escaping. I have gotten a lot of this with .45 bullseye loads. As long as you are in the ball park with your loads, not grossly underpowered, don't let it bother you.
 

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Discussion Starter · #18 ·
THe low powder charge means nothing. It's the pressure generated. TG charge wt. is approx. 25% less than Unique, both have sim. pressures.
This is true. The difference between the three is that the Unique charges (based on previous chrono data) produce an average velocity of about 1184 fps.

The Bullseye charge produced an average of about 1126, the Titegroup about 1126 as well.

Is that enough pressure difference to produce the soot patterns on the BE and TG, and not the Unique?
 

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Straight walled pistol cases like 9mm and even 45 ACP's do this because they do not seal the chamber fast enough to stop some of the gas from escaping. I have gotten a lot of this with .45 bullseye loads. As long as you are in the ball park with your loads, not grossly underpowered, don't let it bother you.
highscore, I agre with what you are saying and your conclusion of "don't let it bother you". But, I've noticed the lack of unburned powder and more consistency across the chrono.
 

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highscore, I agre with what you are saying and your conclusion of "don't let it bother you". But, I've noticed the lack of unburned powder and more consistency across the chrono.
Edubya, I agree that tighter bullet tension will boost pressure and offer more complete ignition of the powder, usually resulting in more consistant chronograph readings, and most likely more accurate loads. At the distance I shoot my 9mm, I really don't worry about things like some unburnt powder. My bullseye gun, shooting Star 185 gr. LSWC's in 45ACP, 750 FPS, would always show a lot of soot but group consistant 1 3/8" groups at 50 yards out of my Ransom rest. I never argue with anything that shoots that well. If it were costing me any points, I would be the first in line to make the loads better.
 
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