Dirty Brass

[wanttobe]

Not sure if this is the correct site for this question.I built an AR 15 pistol 10.5" barrel 223. And have about 50 rounds thru it so far. What my question is, why is the brass so dirty after firing? I have other ARs rifles and they will have a small amount of burnt powder just on the neck. The pistol brass will just about be covered. I would sure like to hear your thoughts on this matter. The loads are light 23.6 of IMR 4064, 50 gn Horn. V max.
Thanks

 

[david kieffer]

Not sure if this is the correct site for this question.I built an AR 15 pistol 10.5" barrel 223. And have about 50 rounds thru it so far. What my question is, why is the brass so dirty after firing? I have other ARs rifles and they will have a small amount of burnt powder just on the neck. The pistol brass will just about be covered. I would sure like to hear your thoughts on this matter. The loads are light 23.6 of IMR 4064, 50 gn Horn. V max.
Thanks

low pressure loads , the brass doesn't expand enough to seal the gas ,add powder and see what happens . good luck . dave

 

[mikecr]

Big chamber clearances also,, same affect as low pressure loads.
Been a long time since I had an AR, but it seems like there was potential for gas timing to cause a slightly early extraction, fouling up the chamber.

 

[wanttobe]

Big chamber clearances also,, same affect as low pressure loads.
Been a long time since I had an AR, but it seems like there was potential for gas timing to cause a slightly early extraction, fouling up the chamber.

mikecr, Could you explain just a little more?

 

[wanttobe]

low pressure loads , the brass don't expand enough to seal the gas ,add powder and see what happens . good luck . dave

Thanks David, I will load up some 24.5 with some 55 gn sierra. That is the load I use in my 18" AR.

 

[Uncle Ed]

Below are the port pressures for the various barrel lengths, "BUT" you have a slow burning powder at or below a start load. Meaning your chamber pressure is too low to seal the case to the chamber walls. So switch to a faster powder and not burn half of it outside the barrel.