AR-10 ejector marks

[criz123]

Im sure this has been posted before but I have been searching to no avail. I am having a small issue of my ar-10 leaving gouges and dents in the brass after firing, normally I would just ignore this, but tonight I was inspecting some spent brass before tumbling and found a hole in the shoulder. The location of the hole is not consistent with the other dents and gouges. I check my brass thoroughly before reloading but even somebody as perfect as me makes mistakes. im using once fired LC 08 brass FLRS 168smk 41.5gr imr4064, chrony avg 2570fps so I don't think it's excessive pressure.

So I have two questions.

1. Did my ar-10 make this hole? if so why?

2. Is there any way to prevent these dents and gouges in the brass?

 

[criz123]

Re: AR-10 ejector marks

 

[match308]

Re: AR-10 ejector marks

Possibly a metal shaving in the chamber that pierced the case during expansion. How many times has that case been fired?

 

[Falar]

Re: AR-10 ejector marks

ARs beat up brass.

 

[criz123]

Re: AR-10 ejector marks

that was the 2nd reloading from me...so 3x

I agree ar rifles do beat up brass, I have a few of them, but I havent had this issue to this extreme before. the pics really don't do the dents justice.

 

[Badshot308]

Re: AR-10 ejector marks

Most of those dings and marks are normal, but the distinct tiny dent in the shoulder isn't. As was said, some tiny piece of debris was in the chamber when the round fired. Take a light and check your chamber to make sure it's out.

 

[okiefired]

Re: AR-10 ejector marks

Gunns, in the first two pics I see a dent in tne sholder, in the next two it is in the neck. Am I seeing it right? If thats the case, cant be a chamber problem, or at least, a burr int the chamber problem.

okie

 

[fastford]

Re: AR-10 ejector marks

its normal

 

[Pat M]

Re: AR-10 ejector marks

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Badshot308</div><div class="ubbcode-body">Most of those dings and marks are normal, but the distinct tiny dent in the shoulder isn't. As was said, some tiny piece of debris was in the chamber when the round fired. Take a light and check your chamber to make sure it's out. </div></div>

the double marks on the neck are normal, the mark on the shoulder isn't normal (? something ? bit of sand in the chamber)

 

[Casey Simpson]

Re: AR-10 ejector marks

Gunns,

AR's are are hard on cases, but they don't have to be.
First, I agree with our fellow shooters above; there was some doo doo in the chamber the case molded around to form that dent, most likely.

Many neck dings are inflicted by sharp edges and burs on the locking lugs on the barrel extension which can be removed carefully and best done on the extension separated from the barrel, but you can also relieve some of the dinging by shortening the ejector spring so it doesn't slam your cases against the lugs' edges and then sling your brass across the fence. All that far-flung brass is not necessary.

And if you get the spring too short an new one is cheap enough. Just continue to adjust it so it puts you brass right where you want them and they won't be so banged up either.

 

[criz123]

Re: AR-10 ejector marks

I appreciate all of the input, i'll definitely check the chamber. I'll be lightening the ejector spring tonight, thanks!

 

[sinister]

Re: AR-10 ejector marks

The little divet in the shoulder looks like it was caused by a grain of sand. The neck marks are normal (should be two parallel marks where the neck hits the inside of the barrel extension on its way out the port).

There should be a slight kiss mark somewhere on the case wall below those two marks where it hit the brass deflector. These can be minimized by using a Tubb Carrier Weight System and one of Slash's heavy buffers.

True, semis are rougher on brass than bolt guns, however by adding mass (the Tubb and the heavy buffer) you delay bolt movement as it takes a little while longer to start rearward motion and acceleration (i.e., a mass or body at rest tends to stay at rest).

 

[pagana]

Re: AR-10 ejector marks

Casey has it right, the marks are a direct result of the barrel extension lugs on the extractor side of the rifle. If you do as suggested above, stone a radius on the tops (no other portion .005"-.010") of the 2 offending lugs and test fire first before removing coils from the ejector spring, it should minimize case damage from firing. Pressure signs in the large frame guns can be seen in the form of ejector marks on the cases heads and loose primer pockets in as little as 3-4 firings.