5.56 DUDS?

[Taylor]

In the process of sighting in my wife's new R-15 yesterday I encountered four successive rounds that failed to fire. All were from the same box of ammo. I was shooting Federal XM193F 55 gr Ball, Lot #SMQ10G037-449. All primers were struck, went through the rest of that box and two more boxes from the same lot with no problems. This is my first experience with this caliber and ammo. I would be grateful for anyone's comments. Thanks.

[Old Dog]

Any time I have a dud, centerfire or rimfire, I give it a second try to see if it'll light off.

It seems odd that four in a row in one box would be duds.  It seems more a rifle issue than a cartridge issue.  I mean they don't hand load those rounds so the sequence they are loaded with primer, powder, bullet and then boxed is there "is no sequence".

Do you know for sure the bolt went all the way forward on each of these?  Not having had the problem with an AR when shooting centerfire I never really paid attention to it.  I have had the issue with a .22 rimfire conversion kit and when the bolt doesn't go all the way forward the hammer will still fall but it only knocks the bolt the rest of the way forward and that absorbs enough of the hammer's force that the rounds don't go off.

Try'em again.

[oladcock]

Possibly the key word there is "new gun". How well did you clean and relube before shooting? All guns need a break in period, depending on the gun, could be 20 rounds, could be 200 before they settle in. Not saying it couldn't be the ammo but I've never seen that in the 3 AR-15's we have...O.L.

[Rocket Man]

If alll primers were well struck, this does sound like an ammo problem instead of a gun problem...

Personally I've gone through a couple thousand Federal XM193 and in all that time, only one FTF -- this is my preferred load.  Your experience is definitely unusual.  If you find any more from that lot I'd report it to the manufacturer.

[Taylor]

I did attempt to fire all the suspect rounds twice but did not disassemble and clean/re lube the bolt before the shooting session. I'll do that before the rifle is fired again. Thanks to all.

[The Kid]

Pull one of the rounds and see if the powder was ignited.
-TK

[dragonfly]

I did attempt to fire all the suspect rounds twice but did not disassemble and clean/re lube the bolt before the shooting session. I'll do that before the rifle is fired again. Thanks to all.

I had the same problem yesterday, same loads. Good ammo by the way. Shot twice primer strike no bang. This was an upper that I had oiled for long term storage. Took bolt apart cleaned oil off with Hoppes #9. Bang, bang the rest of the day    . The extra oil and colder weather caused a soft primer hit. Lesson learned.

D-fly

[oladcock]

Yep, these 5.56/.223's they put a thicker primer in them to help prevent slam fires. In an effort to lighten trigger pull on one I weakened the hammer spring, it'd dent them but wouldn't reliably fire them. $.50 fix. Gunk in the firing pin mixed with cool weather would definately cause it...Have fun! ...O.L.

[AFTERMATH]

Gunk + cold + federal not hiring me = FTF

[GoldFish]

Taylor,
The problems that occurred could be caused by any number of things. 
However, given the circumstances, a very probable cause would be the cold weather combined with the fact of the AR not being cleaned/lube properly before firing.  These could be problems in and of themselves, but these conditions also could have caused the bolt to not seat properly, causing the firing-pin the strike (and indent) the primer, but not set the round off.  Being that the rifle might not have been cleaned, the primer may also have been covered in all sorts of crud that, when cold, gums it up, sometimes causing the firing-pin to not strike the primer hard enough to set it off.

My .02.

---GF

[Big Matt]

We had a number of 5.56/.223 misfires at our event this past weekend. Both shooters using Remington UMC 'value' packs of 200. In both cases it seemed to be a rifle problem with light strikes on the primer.

Big Matt