Update: Independence 5.56 XM193I

[JS-Maine]

Long story short I dropped my rifle on the hardwood floor last night. I figured it's a good excuse to head to the range. The Strikefire was still dead nuts on, but the irons printed slightly right. The Troy fixed front hadn't budged either so I think the MBUS was to blame for a slight shift. The shooting wasn't the interesting part though. This was:

As I was finishing up and I scooped up my brass I saw pronounced ejector markings. I've seen these before, but not this pronounced. This was a lot of Independence 5.56 XM193I. The FC brass seems to gouge much more than LC has in the past. There was even some cratering around the primer strike. Did a thorough cleaning after the session. Softer brass? Any thoughts on the photos below would be appreciated.

Federal:


Lake City:

[markm]

That independence crap is WAY TOO hot. I won't run it. That rear sight is pretty far left, but it is what it is. If it bothers you, I'd get a metal rear sight. The front shouldn't have moved unless the whole handguard shifted.

[GH41]

Who gives a shit! GH

[graffex]

Plastic sights make me cringe

[Milamber]

I'm new her but in for a penny. It would strike me that the FF( I assume) hand gaurs has shifted. Easy fix I would have thought, just a question of losening the handgaurd and refitting snug and another range trip. But as long as it does zero and you can flip the rear sight it will work.

[Airhasz]

Who gives a shit! GH

OP obviously!

[26 Inf]

I'm not liking the way those cases look, here's sometime I swiped from somewhere, maybe you can link to the article:

[GUNS Magazine, May 2010, “Reloading Puzzles & pieces thereof”, Glen Zediker]

Ejector Marks – A shiny mark on the back of the case head indicates that enough pressure was present to flow the metal of the head into the ejector recess of the bolt face. If these marks appear only on the new cases, and if older cases using the same load show no ejector marks, it is possible that new cases are from a production lot that was annealed to a softer condition. In either case, ejector marks are a definite sign of pressure and the load should be reduced accordingly.

Loose Primer Pockets – This condition is detected by the new primers seating too easily. Cases with loose primer pockets have usually been exposed to hot loads and need to be discarded. Continued use may result in gas leakage around the primers.

Gas Leakage Around the Primer – This is indicated by a black, sooty appearance around the primer and is a sign that the primer seats loosely in the primer pocket. Discard these cases and reduce the load to a lighter charge.

Flattened Primer – Where this condition is accompanied by other signs, it is due to excessive chamber pressure. However, flattened primers can also be an indication that the resizing die was improperly adjusted and has changed the shoulder position of the case. This causes excessive headspace and allows case stretching. The flattening is a result of the case moving forward slightly upon impact from the firing pin. Ignition shoves the primer firmly against the bolt face, and when the pressure from powder ignition reaches its peak, the case head stretches until it contacts the bolt face, telescoping the primer and giving it a flattened appearance.

Heavily Cratered or Extruded Primers – This condition should not be confused with the light cratering that can occur from a poorly fitted or badly worn firing pin. Look to the history of your rifle for correct analysis of this symptom. However, if other pressure indications are present, significant cratering should be regarded as a sign of excessive pressure.

[ScatmanCrothers]

That independence crap is WAY TOO hot. I won't run it.

And so much of it has flown off the shelves over the past year and a half it's unnerving. Variances all over the place with higher end pressures passing up some of my maxed out loads. A resident Bass Pro "expert" told me it's mild M193 so there was nothing to worry about. smdh

[JS-Maine]

That independence crap is WAY TOO hot. I won't run it. That rear sight is pretty far left, but it is what it is. If it bothers you, I'd get a metal rear sight. The front shouldn't have moved unless the whole handguard shifted.

Thanks for the heads up on the Independence. I read as much as possible, watch reviews, etc, but that's the first I've heard of Independence 556 being a hot load. The ejector smear blurring up as it is seems fitting with higher pressures. Good to know.

The hand guard doesn't show any visible signs of shifting. It is locked down very well. The FSP and the RD are locked in as well. Looks like the MBUS is due for replacement.

[sinlessorrow]

I have used a ton of Independence M193, its just IWI M193 and have never seen cases like that. Could be a bad lot.