Dented case mouth cause(s)

[jsbhike]

I have noticed I am getting dented case mouths in a 5.56/.223 16" mid length gas upper, full auto BCG, and H buffer that gives 3'ish ejection and 100% reliable.

I think this is a recent change, but some chance I am noticing due to getting back in to reloading vs. not paying attention to brass or just not picking up at all.

Have the work around patch of Velcro ready for the next shooting trip, but curious what in the system is the cause since dented mouths seems more of a .300 issue vs. further down the case when dents happen to 5.56.

[AKDoug]

There really is only one place it can be hitting and it's the brass deflector. Remember that a 3 o'clock ejection angle is AFTER it hits the brass deflector. If it just started cropping up, maybe change the ejector and extractor springs and see what happens. After that, maybe a change to an H2 buffer which is what I run in all my middies that aren't set up with A5's.

[jsbhike]

I figured it was likely a balancing act between the ejector and extractor, but wasn't sure if it was flinging the brass too soon or too late in the cycle. Surprised me there is barely a brass mark on the peak of the deflector considering the case mouths look like D's.

I forgot to add, the extractor has had the O ring on it from day 1. I have seen mention of many ditching those due to causing reliability problems, but nothing about brass denting which is ultimately a non-issue beyond reloading concerns.

Nothing seemed obviously wrong(stiff, sloppy, or chipped) with either extractor or ejector so it all seems to be a split second timing issue with a subtle cause.

[markm]

I'd bump up to an H2. A 16 inch middy will run that. I'd do this even if there were not case mouth dents. It'll be interesting to see if it changes that symptom.

[Uni-Vibe]

Did you change the ammo about the time the dents started?

I don't have dents, but I notice that my 20" ejects underpowered Eurotrash steelcase stuff about 120 degrees. Spec grade stuff or my handloads end up at about 70 degrees. So ammo makes a big difference in ejection.

[jsbhike]

Did you change the ammo about the time the dents started?

I don't have dents, but I notice that my 20" ejects underpowered Eurotrash steelcase stuff about 120 degrees. Spec grade stuff or my handloads end up at about 70 degrees. So ammo makes a big difference in ejection.

You stirred my memory cause I do recall seeing some Tula steel with slightly dented mouths during clean up so maybe an all along thing.

Unfortunately it isn't ammo related because I just checked the recent Malaysian M193 I fired and it has dented mouths along with the reloads of M855 pulls over 23.0 BL-C(2) (weak), Hornady 55gr SP over 25.5gr H4895(fairly hot), and 62gr Gold Dot over 25.1gr Varget(mid to warm).

[ViniVidivici]

I'd bump up to an H2. A 16 inch middy will run that. I'd do this even if there were not case mouth dents. It'll be interesting to see if it changes that symptom.

This. At least try and see.

I run H2 for everything, 11.5, 16 carbine and mid, even 18. Everything runs better and smoother.

I do reload brass out of those too. No major case mouth dents.