[TSloper]

Here's the scenario...

XM193C - 120 rnds - no issues
Hornady 75gr TAP FPD - 20 rnds - continual feed/extract issues
XM193C - 120 rnds - no issues
Hornady 75 gr TAP FPD - 20 rnds - continual feed/extract issues

Each PMAG (4) held 10 rnds of the Hornady. The issues were not specific to any one PMAG. I've never had any issues with XM193C.

Any suggestions or thoughts?

Thanks,
Tim

 

[Zeus]

Measure the overall length of the cartrige with a caliper and compare it to XM193.

 

[SkyPup]

Are these by chance the Hornady 75 grain in the steel case?

 

[Lt Tim]

I shoot TAP as my duty ammo. In fact due to the fact that the department buys it, I have shot ALOT of it in my 556. I have never had a FTF with anything in this rifle. I love it. Plain and simple.

I have even used the hated Sig mags, and still no issues. Maybe I'm just lucky, but TAP has been excellent for me.


Tim

 

[TSloper]

Ok so I hate not know why things aren't working so I went back to the range to get a better handle on this. I should rephrase and state that the only issue is a failure to eject... not extract or feed.

I did not clean the weapon from the other day as I didn't want to introduce too many variables. This morning I shot XM193C, PMC 223, and the Hornady TAP.

First test - PMC 223, Gas valve setting 1
- one failure to eject out of the 20. The next round had fed into the chamber when this occured.

Second test - Hornady TAP 75gr 223
- two failures to eject within the first 5 rounds
- I switched the gas valve to setting 2 and did not have one single failure for the remaining 15

Third test - XM193C, Gas valve setting 1
- absolutely no failures through 20 rounds

Fourth test - PMC 223, Gas valve setting 1
- started to fail to eject, switched to setting 2 and the remaining rounds fired with zero issues

Fifth test - Hornady TAP 75gr 223
- Gas valve setting of 2, zero failures through 20 rounds


It looks like the 223's do not have enough pressure to eject correctly when the weapon is dirty and on setting 1. My next test will be to run some Hornady and PMC through a "clean" weapon with the gas valve set to one.

I just stripped the rifle and there is quite a bit of carbon in the gas valve and tube. Would this be enough to cause the behavior I'm seeing with the 223 ammo or is this a sign of something else? The 5.56 ammo works flawlessly.

BTW... everything I shot today was dead on at 25 yds.

Thanks,
Tim

 

[TSloper]

Are these by chance the Hornady 75 grain in the steel case?

These are the Hornady TAP FPD 223. Silver/shiny cases.

Tim

 

[Zeus]

Had you fired the weapon before without a problem or is this the first time shooting it? Have you cleaned and lubed it per the "new arrival" instructions on the forum, is it broke in? If it's broke in and had fired fine before are you sure the gas valve and tube are installed correctly? Have you tried firing without a magazine in the rifle, loading the rounds manually one at a time through the ejection port? If so, do they eject properly without the mag in? Are you using the stock muzzle break or did you change something there, suppressor maybe? These may seem like dumb questions but just trying to get all the info possible to help you.

 

[ullie]

...clean your 556...especially any grease if present...cycle it 300 times...lubricate it properly...then shoot it..you shouldn't have any malfunctions using TAP...or any "reasonably good quality" ammunition loaded to SAAMI specifications... "authentic" XM193 is loaded to greater pressure levels than SAAMI spec (commercial) ammunition...best guess...you're gun is new and a little rough around the edges...

... http://www.sigarms556.com/viewtopic.php?t=1428

 

[SkyPup]

.you're gun is new and a little rough around the edges..

ditto to that, you need to run at least 200 rounds through it before it gets broken in good.

 

[TSloper]

The weapon had over 400 XM193C rounds before the last couple of days.

So I thoroughly cleaned the weapon and used CLP rather than TW25B. I just left the range with the same result... 223 will not eject reliably using setting 1. With setting 2 it was 100%.

I don't want to send it in but clearly something is not right. It's had plenty of rounds to smooth anything out and it behaves the same way with 2 common 223 rounds.

The upside is that at 25 yds the grouping with the 75 gr can be covered with a quarter. Lol

Tim

 

[SkyPup]

Well I'm glad to hear she is shooting accurately!

But really something sounds wrong, both my SIGs chew and spit out whatever I feed them from my PMags, especially my 75 grain Hornady reloads. I've never used the 2nd setting for anything.

I even shot 200 rounds of Remington .223 45 grain varmint loads and they all cycled fine.

Something sounds fishy, hope you figure it out or it works itself out.

 

[KuroNeko]

FTE as in, leaving the case in the chamber? Or a stovepipe? What do the failed to eject case rims look like?

I got some KG-1 and it melts off carbon from the chamber and crown that Breakfree or Hoppe's never got (based on the blue mop and Qtips). Works great on the piston/gas valve too.

 

[SkyPup]

Are these by chance the Hornady 75 grain in the steel case?

These are the Hornady TAP FPD 223. Silver/shiny cases.

Tim

Okay, I believe that this Hornady ammo is the STEEL CASE as that is the only Hornady .223 with the shiny silver cases.

If this is the steel cased Hornady .223, don't use it in your gun, only use brass cased ammo.

See this for more info:

http://www.ar15.com/forums/topic.html?b=3&f=16&t=487409

 

[KuroNeko]

...
These are the Hornady TAP FPD 223. Silver/shiny cases.

Tim

Okay, I believe that this Hornady ammo is the STEEL CASE as that is the only Hornady .223 with the shiny silver cases.

If this is the steel cased Hornady .223, don't use it in your gun, only use brass cased ammo.

See this for more info:

http://www.ar15.com/forums/topic.html?b=3&f=16&t=487409

If he's using the TAP FPD, then according to Hornady's site, it's a silver/nickle case, not the steel practice case, which should aid extraction.

Hence my question of what type of FTE, after reading the OP again though, the weak extraction could be due to a number of things. Bad piston spring, fouled or bad piston rod, fouled or out of spec gas port, dirty clingy chamber, ...

If you don't want to get ready to send the rifle in just yet, I'd baseline by cleaning/inspecting everything thoroughly and start with the TAP and PMC ammo to see what happens. With a clean rifle, if it still fails to eject the .223 cases vigorously on setting 1, somethings wrong that Sig should address.

 

[TSloper]

The rifle went back to Sig on Monday. The bottom line is that dirty or clean this rifle would not eject (extraction works fine) .223 reliably. The only way .223 would eject without failure was setting the gas valve to setting 2. 5.56 ammo (XM193C) never fails on setting 1 even when the .223 does.

I'll post an update once it is returned.