Dented case on ejection

[BjornF16]

Performed the modification described in the link above...shot 5 rounds with 4 failure to extract.

Could it be possible that I have undergassed the system with my adjustable gas block (it is less than 1 turn from fully closed)? This gas setting worked fine prior to the modification.



5Feb12_Light_grendel.jpg

[rasp65]

Bjorn The modification of the ejector shouldn't effect the extractor.

[BjornF16]

Sorry, let me be more precise. The case was extracted from the chamber in all cases but was not ejected properly.

Four shots resulted in spent case remaining loosely just above magazine. This of course interfered with insertion of next cartridge (this occurred twice). I then shot with empty magazine inserted three times. Twice the result was loose cartridge sitting on top of magazine with bolt locked back. Once the case was properly ejected.

[rasp65]

Bjorn How much of the spring did you remove?

[Drifter]

Might have trimmed the ejector spring too short.

[stokesrj]

Sorry, let me be more precise. The case was extracted from the chamber in all cases but was not ejected properly.

Four shots resulted in spent case remaining loosely just above magazine. This of course interfered with insertion of next cartridge (this occurred twice). I then shot with empty magazine inserted three times. Twice the result was loose cartridge sitting on top of magazine with bolt locked back. Once the case was properly ejected.

It sounds like the spring is now too short. I hope you have another and can trim it less.
Bob

[BjornF16]

I trimmed enough spring to leave it protruding just under 1/16" beyond face (I left a little more than the instructions said). I'll swap out the spring after trimming the new one by half as much.

I did go back to the range after opening up the gas block more...no difference. I gather there is a difference between 5.56 and 6.5 when it comes to ejector force?...

[rasp65]

Bjorn I have done it to both 6.5 and 5.56 bolts in both cases I left it longer than what the instructions said. I think that I removed 2 or 3 coils depending how you look at the spring. I wanted to make sure I didn't take too much off especially since the spring is kind of hard to hold securely,as you probably found out.

[sneaky one]

Try an extractor up-grade, such as the D-fender, to eliminate extraction problems, my AA upper was a nightmare first time at the range-same as yours, bjorn = empty brass on top of fresh round in mag., then zero extraction. I felt the need to send the upper back. A new D-fender cured that. As far as the ejector spring- cut 1.5- 2 coils-then leave it alone.

[smoke13]

1) Examine the face of the spent brass (primer side). Is there a small mar the size of the ejector pin? If so this is an indication that the spring force is to high on the ejector pin. (Use advise given above to solve problem)
2) Examine the spent brass groove (where the extractor hook grips the brass). Is there marring and digs in the brass? If so you could have a problem with the extract hook digging into the brass and not letting it go like it should when flinging the brass out which. This could cause it to rotate around and dent on the extractor itself. Investigate if you need to de-burring the extractor hook and determine if you have the correct bolt & extractor for the headspace of this barrel. The AA barrel’s are head spaced for their own bolt and extractor combination (AA bolts are milled .011” deeper and a custom, improved extractor is used with the bolt. This will not work correctly with a barrel that is headspaced for a standard AR .30 cal bolt (.454 bolt depth, and .136 diameter).
3) When your brass lands forward of 3:00 it is often an indication that the brass is bouncing off of the deflector or the like which sends the brass forward landing at 2:00. This is either due to over gassing or ejector issues usually. (The over gassing throws it further toward the 5:00 but if it is bouncing of the gun it will land more at 1:00 or 2:00)
I initially had the same dents on my brass when breaking in the system. It was due to over gassing. I have a Mega side charge upper which has a sharp corner where the brass ejection port and side charge slot intersect. The brass was being flung right into this corner creating the dent and then bouncing forward to 2:00. I did 2 things to fix this. 1) Swapped the buffer out from a carbine buffer to a T2 (using a Spkies ST2). The heavier buffer slows down the velocity of the bolt carrier slightly. 2) Secondly I dialed down my PRI adjustable gas all the way to closed and opened it incrementally until it had just enough gas to reliably cycle the bolt. On my system this was .5 turns from closed. Running the carrier as slow as you can in my opinion saves on wear and tear and your gun and loads the round a little more consistently because it reducing the slamming effect which can only help with accuracy.