Uneven Residue Distribution On Casing

DrSpaceJam

DrSpaceJam

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I've been experimenting with some reloads in .38 Special. With one particular load, I've begun seeing an odd phenomenon I've never experienced before. On cases fired in my revolver, there is the usual degree of fouling on the case. When firing the same load from my rifle, I get a long, pronounced streak of carbon down one area of the casing. Picture below.

pgkDXTm.jpg


I've never seen this pattern of fouling before and am just curious about what exactly might be causing it. The cases are fine (no signs of too much pressure and the load was minimum anyway). For reference, the load is:

130gr lead RNFP bullet
5.5 Gr AutoComp
Winchester .38 Special cases
CCI Small Pistol Primer
1.460" COL

I really like the accuracy out of the rifle so I'm hoping this isn't a cause for concern.

Thanks for any help/thoughts.
 
myself I do not worry about it, believe its the gass escaping past the casing, tighter chamber would help but the brass is still not bulged and its fireing well?
 
If you can examine the rifle chamber in the area that matches up with the fouling on the case you may see what is happening.
Keep in mind that the bullet has to travel further in a rifle and so the pressure will be applied on the case for a longer period of time, could explain the greater fouling.
 
What you are seeing is gas leaking past the brass to the rear. Light loads don't have enough pressure to expand the brass against the chamber walls to seal chamber. It's quite common in light pistol loads. To fix it you'd need to shoot a load that develops more pressure, either a heavier bullet or more powder, or both.
 
jethunter said:
What you are seeing is gas leaking past the brass to the rear. Light loads don't have enough pressure to expand the brass against the chamber walls to seal chamber. It's quite common in light pistol loads. To fix it you'd need to shoot a load that develops more pressure, either a heavier bullet or more powder, or both.
Click to expand...

This^^
Not enough pressure to seal the brass to the chamber. Nothing to worry about at all.
 
5.5 grains of AutoComp is just the start load for a 130 grain cast bullet out of a revolver. You need to work up the load for your rifle. The wee bit of carbon leaking isn't anything to worry about though. Rifle chambers are different than revolver cylinders. The leak is likely at or near the extractor. No big deal.
Your rifle a .357? You may want to think about using .357 brass loaded to .38 velocities if it is. Not a big deal, but it'll eliminate the lube gunk build up in the chamber. Only matters if you ever opt to shoot .357's after shooting .38's. You can do the same thing with a .357 revolver.
 
Just like above, ive seen the same thing on mine till I loaded with a bit more powder. Nothing to worry about, just not a clean burn and expansion to the case walls because of low pressure.
 
Nothing that a heavier load and a good crimp won't solve, if you want to maintain the same powder charge try crimping a little heavier
it might just do it for you. It is a normal sign of low pressures and weak crimp.
BB
 
Spawn-Inc said:
jethunter said:
What you are seeing is gas leaking past the brass to the rear. Light loads don't have enough pressure to expand the brass against the chamber walls to seal chamber. It's quite common in light pistol loads. To fix it you'd need to shoot a load that develops more pressure, either a heavier bullet or more powder, or both.
Click to expand...
This^^
Not enough pressure to seal the brass to the chamber. Nothing to worry about at all.
Click to expand...
Yup, thirded.
 
I have this on my .45ACP as well. Loading relatively lighter loads for comp use...

I have a weak wrist. =)

Seems to help with fast follow-ups competing against 9mm. I'm going to try running hotter soon though.
 
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