Black smut on one side of the case??? 40 S&W


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cowtownup
August 31, 2013, 07:56 PM
I'm noticing black smut on one side of my cases after firing. These are some of my handloads loaded to the following specs:

155 gr Berry RS
8.0 gr Longshot
1.125" OAL
S&B Small Pistol Primer
once fired cases
fired from a M&P40c

I tumbled and cleaned these cases well before I loaded them so this is certainly from the firing process.. Would this be the case not sealing good against the chamber during firing? Why would it happen on just that one side? I should have marked a round so I could determine which side of the chambered round this was occuring on. Anyhow, any ideas?

The top 3 are the clean side of the case and the bottom 3 show the side in question.http://i185.photobucket.com/albums/x256/cowtownupp/IMG_20130831_193744_407_zpsdc7f800a.jpg (http://s185.photobucket.com/user/cowtownupp/media/IMG_20130831_193744_407_zpsdc7f800a.jpg.html)

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rcmodel
August 31, 2013, 08:02 PM
Low pressure load is not expanding the case to seal it.

It gets more smudge on one side then the other because:
1. It is laying on the bottom of the chamber and there is more room for gas leak on the top before it reaches full pressure and seals off.

2. Or, the brass is different thickness on one side of the case, so the thiner side expands more then the thicker side.
And it leaks more on the thick side

Up the load if you are going to use Longshot.
Or change to a faster burning power that will expand the case sooner in the pressure curve.
And the problem will likely go away.

rc

cowtownup
August 31, 2013, 08:07 PM
Thanks a bunch RC... I'm gonna work it up a little bit and see....

gamestalker
September 1, 2013, 02:35 AM
I'm not sure that Longshot is the ideal powder for plated, cause Longshot doesn't perform well at the lower end. I load almost exclusively with it in numerous cartridges, and I've found that it does very well up at or near max. My 155 gr. JHP's run on 9.3 grs. and are very clean burning, high velocity, and accurate too. But I don't know if you can push a standard plated bullet that hard, maybe a TP though?

RC has answered it for ya. Increase the charge until things clean up, and if you have a chrony see how consistent the fps is.

GS

cowtownup
September 1, 2013, 06:56 AM
Thanks GS.. I really need to invest the money on the chronograph if I'm gonna do much handloading...

Kuyong_Chuin
September 1, 2013, 11:20 PM
Thanks GS.. I really need to invest the money on the chronograph if I'm gonna do much handloading...
Walmart sells the F1 Chronograph for $82 and some change online.

Brad.
September 1, 2013, 11:39 PM
I suggest a faster powder...my experience with longshot and 40 is the same its just too slow...try 231, hp38, bullseye, clays or unique it'll make a much better load...if you are looking for speed power pistol...but I don't see a real advantage.

jim243
September 2, 2013, 12:36 AM
Low pressure load is not expanding the case to seal it.


What RC said.

Jim

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