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Sig556 Over Gassed and Destroying Brass?

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Picked up a Sig556 Pistol that will be the host for an SBR project soon and took it to the range for the first time yesterday.

Is it just me or is the rifle way overgassed? Brass is ejected about 1-2 o'clock and about 35'. The fired brass is significantly dented with a crushed case mouth and it appears the extractor is almost tearing off the cartridge rim.

Anyone else experience this?
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Same issue with my 556 Classic Swat. The case mouth of ejected brass that I'm able to recover looks like a D. Moreover, there are usually a few dents in the body of the cases, just for good measure. As you point out, brass gets ejected into outer space, too. If they are all like this, then it's safe to say that the 556 is not a platform for the fussy handloader.

What makes this particularly annoying is that my 556 delivers good accuracy only with match ammo. So I try to feed it Blackhills 68 gr. match. It's a pity to see that lovely brass get bashed. If the gun liked Wolf ammo, then that's all I would feed it, but alas, it doesn't.

Another side effect of that violent extraction is that the ejected cases will eventually chip the paint off the receiver by the ejection port. Recently, I took a a bicycle tire patch and cut it to fit right by the ejection port. I used rubber cement to fix it in place. The patch is flat black and blends in with the finish of the receiver. I haven't had a chance to test it yet, but besides saving the finish on my receiver, I'm hoping that my improvised rubber "port buffer" will soften impact and thereby lessen the damage to the brass as well.
 

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I use a 1.5" strip of electrical tape to the rear of the ejection port, brass has always done that on my 556 Classic, nice pile about 15' out at 2 o'clock.
 

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Discussion Starter · #7 ·
Here is a teaser for those who have been waiting patiently.

Note the difference in the brass. The brass on the left is using the stock normal position, brass on the right is from the improved valve.

I sent out a test valve to a member who has the ability to test things out with a suppressor. Pending his results, I'll be able to start cranking these out for everyone.


 

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Discussion Starter · #9 ·
Any chance one of you could post some pics of where you are putting the tape, rubber etc. to protect the finish and help save the brass?
Thanks
If you are referring to my post, that is not a result of putting Velcro on the frame. That is from using an improved gas valve on the rifle and fixing the root cause: the rifles come horribly over gassed from the factory.

More information here if you'd like:

Group Buy: Sig556 Redrilled Gas Valves | SIG Sauer 556 Forum
 

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Here is a teaser for those who have been waiting patiently.

Note the difference in the brass. The brass on the left is using the stock normal position, brass on the right is from the improved valve.

I sent out a test valve to a member who has the ability to test things out with a suppressor. Pending his results, I'll be able to start cranking these out for everyone.


YIKES!!

That stuff on the left looks like it was molested by a Hakim!!
 

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Definitely interested...

I'd want one for my 556R (7.62x39mm), if you got the gas holes just right for this round.
 

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Very interesting thread.

Seriously, one of the major features of the AR system that attracted me to it in the first place was how gentle it is on brass. I shoot almost exclusively handloads in my 7.62 NATO and 5.56 rifles and would pop a cork if I was stuck with the brass on the left.

Good job and glad to see your fix worked out.

And yeah, I can only imagine it is adding some life to the rifle, too!
 

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Any chance one of you could post some pics of where you are putting the tape, rubber etc. to protect the finish and help save the brass?
Thanks
Here is what I do with electricians tape.
 

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