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Old 09-23-2013, 10:24 PM
.Steve. .Steve. is offline
Join Date: Oct 2009
Posts: 828

Soot on the case is a race between gas generation and case expansion.

Pressure and speed of making pressure expands the case and prevents gas from leaking down the side of the case prior to pressure sealing the case against the chamber walls.

Low pressure and a slow rise of making pressure expands the case slowly and allows gas to leak down the side of the case which sometimes means the case never actually "completely" seals.

Aguila is generally a low pressure slow velocity item noted for both characteristics. Thus it is dirty and sooty.

Harder brass accentuates the problem. Soft brass makes it seem as though the pressure is adequate. Old brass tends to get hard. Poor quality brass is stiff at the case mouth end where it need not be so.

Firing and reloading and firing and reloading makes for harder and harder brass.

You get the idea. The real point is that carbine brass is fairly strong and the loads generate a working pressure that just barely seals or doesn't seal the case to the chamber with most brands.

What you see is normal for the ammo you are using. Other brands won't do it due to softer brass or loads achieving full pressure faster.

Long cases prevent the bolt from running forward, keep the bolt from rotating to full lock up, and are the mother of all carbine problems. Most factory ammo is 1.280" + 0.001. +0.002, in that area.

Carbine brass from a factory at 1.290" is junk.

If the bolt does not rotate locked, the hammer still drops and hits the back of the bolt. Hopefully, it does not also hit the firing pin while the bolt is unlocked. All you hear is a click. Which often rotates the bolt closed.

As a practical matter, most carbines fire any time the bolt is half rotated to lock LONG before the slide over runs the right bolt lug cam extension. The symptom is a carbine firing with out the action cycling, AND a fired case sitting in a seemingly closed bolt/chamber.

The solution is to avoid long ammo.
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Old 09-23-2013, 11:39 PM
Beast556 Beast556 is offline
Join Date: Aug 2013
Location: Colorado
Posts: 20

All my brass comes out looking like yours.
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Old 09-24-2013, 12:38 AM
ricco ricco is offline
Join Date: Oct 2009
Location: Upper Valley, NH
Posts: 242

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Old 09-30-2013, 09:44 PM
RdKryton RdKryton is offline
Join Date: Aug 2011
Location: Guthriesville Pennsylvania
Posts: 1,872

GGaskill is spot on. About a year ago I got 500 rounds of Aquila ammunition from CMP and about 40% were over maximum case length before they were even fired! Not by much though and my NPM is worn enough that it didn't make a difference when fired. Just something else to look for with that ammo. Mine were also very dirty after firing.
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Old 10-02-2013, 05:02 AM
J.R.2009 J.R.2009 is offline
Join Date: Oct 2009
Location: Mt. Pleasant, SC
Posts: 8,224

OP ALL my brass comes out dirty. I don't care who makes it. I have several brands, including the 1350 rounds case CMP sold a while back that is ALL LC military. Plus all my reloads using 296 powder. All 13 of my carbines shot well with the Aquila, Remington, U.S. military made ammo and several other brands.
With only one mag to shoot with I'd not condemn the ammo or the carbine for feed problems, even some stove pipes until you get a few more mags. U.S.G.I. or the new Korean mags are what I use.
Just FYI, take your mag apart and make sure the spring is installed with the taller, cut ends facing the rear of the mag. If not installed that way you can/will cause feed problems.

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Old 10-02-2013, 06:58 AM
Hacker Hacker is offline
Join Date: Oct 2009
Posts: 918

All of my brass, regardless of manufacturer, comes out looking like that from two CMP Carbines I shoot.
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OEF veteran 2007/2011
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brass, carbine, dirty, inland, soot

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