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Discussion Starter · #1 ·
I've been shooting the 3AT a good bit over the last few weeks and I really enjoy shooting it.

One thing that the gun does is blacken the fired cases a lot more than any of my other handgun calibers. It's not just a little bit but a lot. It happens on all ammo, factory or reloaded. The gun fires, cycles, and is fine in all other ways.

I know that when a cartridge is fired the brass case expands and seals off the chamber until the pressure drops.
The blackened cases tell me that there is burned powder residue blowing by the chambered brass case when it's fired.

Is this normal with the 3AT? If not what could be the cause?
Oversized chamber?
Timing issues?

A non issue and not even worry about it?

Thanks
 

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Hmmm.  Mine doesn't do this with either WWB, commercial reloads I used once or my own reloads.  On the other hand, I don't see where it's a problem either, just annoying.

How many different brands of factory ammo have you tried, and what Manufacturer were they?
 

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Discussion Starter · #3 ·
Factory ammo- WWB from walmart and RWS from Midway.

Reloaded ammo using Berry's plated bullets and Missouri cast bullets.
Powders used were Power Pistol and W231.
 

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Non-issue I would think.

Case seal is dependent on a lot of things all happening at the same time.

1. Primer fires and starts the bullet moving forward.
2. At the same time the powder ignites and begins to burn.
3. Bullet clears the case mouth.
4. Bullet gets in the rifling, friction increases, powder completes burn, and chamber pressure rises rapidly.
5. Case expands fully and seals the chamber.

Things that effect case seal include.

A. Power of the primer charge.
B. Burn rate of the powder used.
C. Clean or "dirty" burning power.
D. Hardness of the brass case.
E. Bullet tightness in the case.
F. Bullet fit in the barrel.
G. Loose or tight chamber.

Although the complete firing cycle is almost instantaneous:
1, 2, 3, & 4 take place before max pressure is reached and a complete chamber seal has occurred, so soot gets between the case & chamber with some loads more then others, depending on A. through G.

rc
 

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Discussion Starter · #5 ·
rcmodel- Thanks for the detailed info

When I recover the fired brass I usually inspect them for potential problems. After it's cleaned it in the tumbler I inspect it again for bulges, etc. So far none of the blackened cases have had any split mouths, bulges or loose primer pockets and I've probably reloaded those cases 3-4 times so far.
It could be a non issue.
 

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The more times the cases have been reloaded, the more work hardened the case neck becomes.

That in turn takes more pressure to expand it for a tight seal at the beginning of the combustion cycle.

rc
 
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